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NAS and RAID plan for church

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December 12, 2012 5:11:57 PM

Hello,

I'm working as the office administrator for a small church. Our IT needs are pretty modest since we only have a few employees currently, but when I came in to the position the technological level was pretty basic. There is one main computer in the office (mine) that has all of the important files and records to make the church run, and then one laptop (connected to a mixer) that runs all the audio/visual for our services. The only backup solution we have is a 320GB MyBook connected to our office PC.

I'd like to increase our backup capability, while also putting in place something that will serve us well for many years to come. I've looked into it and think a Network Attached Storage box will be a good solution, since I can have a central server to automate and store backups for the computers we currently have, and also for the personal laptop of our minister and any other employees we hire in the future. It can also function to share files between our computers, which I think will become more necessary as we get into higher quality sound and video production in the future. All the other features (web hosting, mail server, etc) would be icing on the cake.

I'm looking at a 5-bay NAS that can be expanded with 5 or 10 more drive bays. I want to have about 6TB of storage to start with, but I can see our needs increasing to 20-30TB depending on how large our church gets and how much audio/visual we start doing. (I'm going to want to do complete versioned backups of every computer we have).

The NAS I'm looking at can do RAID 5 or 6 (all the other types as well). I've read that RAID 6 is almost a necessity at this point, because the large sizes of today's hard drives can make a bad sector very common when rebuilding an array, so you need that second drive of redundancy. But I've also read that I need to have an external backup of the entire array, in case 2 drives fail while rebuilding in RAID 6 (much more likely if I have 10-15 drives). Since I'm working in a relatively low-pressure environment, I'm not worried about server downtime very much.

1. Since I'm going to be using the NAS primarily to store backups anyway, should I be worrying about RAID 5/6 for it? Does me planning on hosting shared files on it make it necessary?
2. If I use RAID, do I need to plan for double the storage amount, to backup the array itself?
3. If I do buy double the storage to backup the NAS itself, do I even need to use RAID? This might save me buying a couple drives, since I won't have the RAID overhead.

Sorry for the long post! I hope I've explained everything clearly. Thanks for any help you can offer.

More about : nas raid plan church

December 12, 2012 5:18:36 PM

Hi :) 

Budget ?

All the best Brett :) 
December 12, 2012 5:28:07 PM

$1200 is where I'd like to stay close to. The NAS I'm looking at is $800 initially, then I'd need 6TB of available storage, so around $400 for the drives. We would spend more down the road to expand the NAS and buy more drives, but we don't need that right now.

And in case anyone asks, I've chosen a NAS instead of building+setting up my own server because of tech support availability, Windows Server 2012 licensing cost, and because I don't want to invest my or other employees' time in learning how to set up and operate a server.
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December 12, 2012 5:30:43 PM

Edit: I forgot to mention, the $400 for drives is only if I don't have to use double the storage amount. If I have to do that, then I will either spend more or start out with half the storage.
December 12, 2012 5:48:19 PM

EDIT:

Just saw your latest posts and budget. If your needs are going to be scaling over time, then in the short-run you might indeed be better off with one or two small NAS boxes, just to keep your startup costs down. I would recommend Red drives for those.

Longer term, if you end up storing 30+ TB, you will outgrow those and need a different solution.

PURPOSE:
RAID helps you recover quickly from a disk failure. Backups are what protect against viruses, theft, fire, etc. You probably need both in your situation. One option would be to have a NAS as your primary file server using RAID 5, and a separate NAS for backup - of both your NAS and your client PCs. Alternatively, you might do some or all of your backups to the cloud so that you don't need to maintain twice the usable storage space. If you can put primary and backup storage into two separate buildings / locations (and cloud is certainly separate), that provides far better security for your data.

ARCHITECTURE:
When you're talking about 20-30 TB, you're talking about a lot of disks, so you need to think about your overall system plan, drive controllers, and rack space. I don't know of a simple NAS that will support that much storage; if you use 2 TB drives connected to 4-drive controllers, then 20 TB requires 12 drives in 3 x 4-drive RAID 5 arrays plus 2 more in RAID 1. If instead you use drive controller hardware with more ports, you could do e.g. 14 drives in 2 7-drive RAID 6 arrays. You could use 4 TB drives instead, but the cost per GB goes up, and the loss from a single disk failure has a greater impact on rebuild time. Regardless, you're talking about a lot more than 4 drives in a small box. And you actually might have TWO sets of boxes, because you need primary and backup.

ARRAY SIZE AND REBUILDS:
I would recommend breaking up your storage into multiple RAID arrays, so that your rebuild time is shorter, and the backup-restore for a failed array is also smaller. You can use software features to merge the arrays into a single contiguous storage space if that's what you need.

DRIVES:
I've had great experiences with the WD RAID Edition (RE) drives, and less-positive experience with Green and Black editions. I don't use Seagate, but others do and can voice in. To glean some insight into whose drives are better, take a look at the drive certification list for a drive controller card such as an Areca or LSI or similar. You'll see things like "this drive requires a firmware update to work" or "this drive is not supported due to X", which can be telling about overall drive and Manuf quality. The new "Red" drives might be good for you if you decide to go with a bunch of NAS boxes - especially for the backup server.

SOFTWARE:
If you are using a NAS, it comes with software. If you build your own server, you'll need to provide something. A year ago, I would have recommended WHS 2011, but no longer. As a product, WHS appears to be getting phased out. Windows 2012 SBS Essentials is the closest replacement, and supports some of the requirements that WHS does not, such as backing up Win 8 installations running on GPT-formatted HDDs. Windows 8 Pro also has some features which could meet a lot of your needs, such as its new storage space feature. It allows you to specify a cross-drive asymmetric array and add drives on the fly, which is handy when your needs grow.

Anyway, good luck. There are a lot of choices and options both in the SOHO space and in the small-biz space. The only question I have is, what in heaven are you storing that chews up 30 TB?
December 12, 2012 6:02:30 PM

RAID a church? I can arrange a crew from Scandinavia, if you can finance a longboat.
December 12, 2012 6:04:24 PM

personally i'd run a windows home server instance as it would do the backups, redundant storage (WHS v1). use standard PC components without the inflated NAS prices and lack of maintainability
December 12, 2012 6:41:33 PM

Nice beginning budget. It might be more cost efficient to build a server and then add NAS storage as you need it. A good server box can host an impressive raid array on its own and be a traditional server providing your church with email and domain control all at the same time.

Be sure to expand your switch as your storage expands. I can’t tell you how many kids I see with 40T + of NAS (read-movies) all plugged into an unmanaged Cisco (Linksys) router/switch. Small switches are fine for home applications but as your IT footprint expands your network carrying capacity needs to expand as well.

I’d also set aside a small budget for your training and get into an A+ class. The more educated you are the better equipped you’ll be to make intelligent decisions for your employer.
December 12, 2012 7:17:25 PM

Thanks for the replies so far.

I could build a server on my own, but once I bought the parts ($400) and the Windows Server Essentials license ($500), I've already reached the price of a NAS. I also don't want to spend the time learning how to set up a server, and whoever takes this position after me may not have the knowledge to operate or maintain a custom-built server, or deal with individual component warranties if something fails. A NAS would make this more user-friendly for us. EDIT: There's another reply advocating a server. I'll certainly think about it, though it would mean more work for us. However, I still have to deal with the RAID question, explained below.

The reason for so much storage space is expansion potential. I could see in the next year having seven computers I would want to back up, and most computers have at least 1TB hard drives now. I allotted 2-3x the space of the hard drive for long-term backup storage. That's 14-21 TB right there, and that's only if we stay this size. A lot of organizations like us, as they get larger, add a handful of other staff into the mix. The largest files I foresee us working with would be video editing files. 1-2 services a week, 52 weeks a year--that's a lot of audio/visual stuff to work with. We're not at that level yet, but I'm trying to plan for that contingency.

Teramedia, thank you for your explanation, it helps, but I don't quite understand what you're saying. I know that I need backups, but what happens if one of the backup drives fails? I lose the backups, and can just make new ones from the original computers. Hopefully nothing happens to the original comps in the meantime, but I've also lost any versioned history for those comps.

If I RAID 5/6 those backup drives, it helps protect me from losing the backups, right? But if a drive fails, and I put in a new one to rebuild the array, if the rebuild process hits a bad sector then I have again lost all the versioned backups.

So do I just risk that happening, or do I have to set up a redundant backup of the NAS? Then, if one/two drives in the NAS fail, and when I rebuild the array I hit a bad sector, I just replace the drives and copy over from the redundant backup. This is what seems safest to me, but it's also the most expensive, and I guess I'm asking you guys if it's really necessary to avoid losing data.

Or should I just stop at step one, and use the NAS without any RAID at all?


Sorry, longboats are not in the budget. Maybe next year.
December 12, 2012 7:22:34 PM

BVKnight said:
1. Since I'm going to be using the NAS primarily to store backups anyway, should I be worrying about RAID 5/6 for it? Does me planning on hosting shared files on it make it necessary?
2. If I use RAID, do I need to plan for double the storage amount, to backup the array itself?
3. If I do buy double the storage to backup the NAS itself, do I even need to use RAID? This might save me buying a couple drives, since I won't have the RAID overhead.

RAID is not a backup. RAID is for redundancy. Typically if there's a computer which a business needs to be up and running 100% of the time, they will RAID its disks. That way if a disk fails, it does not take down the computer with it.

So if your church needs 100% uptime on this device, you want RAID. If not, then you don't need RAID (though it might be nice to have since hard drives are cheap and downtime is annoying).

Yes RAID devices need to be backed up too. The reason is that backups are supposed to be static offline copies of your files. Say you have a RAID-1 (mirroring). That means you have two copies of every file, so you don't need a backup, right? Nope. The problem is that if you accidentally delete a file, the RAID will automatically delete both copies of the file. *Poof* there goes your second copy. That wasn't a problem in the tape or CD-R / DVD-R backup days which forced backups to remain offline. Nowadays we backup to hard drives so the distinction has gotten a little blurry for people.

You say most of the storage on the NAS will be backups, which normally would obviate the "RAID needs a backup" rule. But ideally the backup should be off-site too, in case the building (and NAS) burns down. Since you're also going to put shared files on the NAS, that means the NAS can't leave the building. So yes you're going to have to back up the entire thing, and take the backup off-site. Or at least that's what you should do. Obviously budget and manpower constraints mean sometimes we have to make tradeoffs with risk in terms of safeguarding our data. Maybe an offsite backup is unfeasible, in which case only the shared files would need to be backed up (since they're the only copies of the files).

If you have a good Internet connection, you can backup to an online service or remotely to a backup device at your home. Otherwise, you should plan on a portable media device which you take home with you at the end of the day. Sans Digital and Mediasonic seem to be the big companies which make simple USB enclosures which glom a bunch of hard drives into one. Or figure out a way to burn to blu-ray (DVD-R is out of the question since you're talking about several terabytes of data).

And Windows Home Server is a popular choice if you're familiar with Windows, but you can build your own NAS and run many variants of Linux or FreeBSD (FreeNAS) which will do pretty much the same thing. I cut my teeth on Unix so I prefer those over WHS (I find the Unix symlinks and user permissions to be more flexible). Be aware the 2011 version of WHS got rid of the popular Drive Extender feature, which was what automatically handled the redundancy for you. Just stick a bunch of drives in, mark which folders you wanted to be redundant, and WHS handled the rest behind the scenes. You have to go back to the 2008 version of WHS for that, but that's 32-bit so is limited to 4 GB of RAM.

If you want a pre-made NAS box, you should check out the Small Net Builder site. They have a pretty thorough database of NAS reviews and benchmarks. Most of the NAS boxes run a Marvell or Atom CPU. A Sandy/Ivy Bridge processor has an idle wattage very close to those CPUs, which was my main concern (since the thing is on 24/7). I opted to pay a little extra to build my own NAS around a Sandy Bridge i5 for the extra horsepower when needed (it has an SSD boot drive and I run several virtual machines on it as well). But that was after I tried out a Synology for a bit before returning it. While my homebuilt NAS is a lot more flexible, the Synology was a lot easier to set up and use. They did a really great job making all the features accessible and simple to use. If I were putting together a NAS for my parents to use, I'd definitely go for the Synology even though it cost more for slower hardware.

http://www.smallnetbuilder.com/
December 12, 2012 7:49:52 PM

That clears things up a bit. First, backups don't tend to get as large as you might think, for a couple of reasons. First, if your users are using the local drive just for workspace, but the server for "permanent" documents, they will never have all that much on their local drives that needs to be backed up. Certainly not the whole 1 TB. Second, good backup software will capture just the changes from one backup to the next, so that you don't have to store a whole copy each time a backup is made. Unless you backup your users' scratch space, not much is going to be different from one backup to the next. I am currently backing up 3 HTPCs and 4 laptops and it only consumes 422 MB total with versioning, even with some music and pics stored locally on one of the laptops.

I'm imagining that you need a server/NAS that does the following:
- file server
- computer backup repository
- possibly streaming content server?
- possibly website for congregation notes, publications, calendar etc. (though there might be better ways to do this in the cloud)

RAID 5 should be fine as long as rebuild times are reasonable - again, breaking it up into chunks helps this for a number of reasons. Using an LSI MegaRAID card, I can rebuild a 4 x 2 TB RAID 5 array in ~4 hours or so. The only times I've had problems rebuilding RAID 5 arrays were when I tried to use software RAID 5 in Windows Home Server 2011, and when I tried to use chipset RAID 5 on an AMD SB850 and an Intel ICH7R, each with incompatible firmware / driver combinations. IMO, RAID 6 only makes sense if you have a few more than 4 drives in the array.

The other requirement you have is backup storage for your files that are served up on your NAS. At your discretion, you can decide whether to backup the system backups folder as well; it might not really be necessary, but the size might be so small as to make it a non-issue. This backup system needs to backup all data on your server/NAS that does not already exist elsewhere, including any operating system and other software that you installed to make the server work. It's purpose is to protect you from data loss in the event of fire, flood, theft, lightning, etc. causing the irretrievability of data from your server/NAS. Again, in order to be effective at this task, it needs to be in a different place - at a bare minimum, in a different room. But better than that, in a different building. And again, you could use cloud services for this instead of buying or constructing a system. Here again, using RAID is not for backup, but rather to enable you to quickly restore operation in the inevitable event of a drive failure, if you happen to have that requirement (and you might not). Everything on this system will be a simple copy of certain data from your NAS/server, and therefore easily regenerated - though possibly requiring a lot of time.

The drive failures you should expect are:

1) laptop HDDs. Over the years, 2/3 of the ones I've had have failed eventually. HDDs weren't meant for being jostled around. Get ~200 GB SSDs instead if you can (over time, budget permitting), to physically "harden" your laptops and also prevent the bad habit of users storing all documents locally.

2) NAS/server HDDs. These are going to be reading and writing more often than your backup server's drives, so they will be more likely to wear out sooner.

3) backup server drives. Put this system in a climate-controlled, dust-free environment, and you might never see a failure before the system's decommissioned. Or, use a cloud service and you are guaranteeing isolation between NAS and Backup for local acts of nature and reducing your maintenance workload by 1 box.
December 12, 2012 8:04:26 PM

One other thought: If your backup system is roughly the same architecture as your NAS/Server system, then you get the added benefit of hardware redundancy. That way, in the event of a catastrophic hardware failure on your NAS, you could retask your backup as the NAS and then construct a new backup (quickly). In the end, it all depends on how much you are willing to pay to reduce recovery times in the event of various kinds of failure, and how much you are willing to pay for "insurance" against acts of God, nature, and malevolence.
December 12, 2012 8:17:44 PM

BVKnight said:
I've already reached the price of a NAS. I also don't want to spend the time learning how to set up a server, and whoever takes this position after me may not have the knowledge to operate or maintain a custom-built server, or deal with individual component warranties if something fails. A NAS would make this more user-friendly for us. EDIT: There's another reply advocating a server. I'll certainly think about it, though it would mean more work for us. However, I still have to deal with the RAID question, explained below.

You mentioned a 5-bay NAS with a 5-10 bay extension. Just be aware that those extensions aren't really recommended for long-term use. Yes they can work in a pinch, but if the cable between the extension and your NAS glitches, the NAS interprets that as a multiple drive failure and your array is screwed. The server has the advantage of each drive having its own independent connection to the computer (though you may need to add some internet SATA cards).

The reason for so much storage space is expansion potential. I could see in the next year having seven computers I would want to back up, and most computers have at least 1TB hard drives now. I allotted 2-3x the space of the hard drive for long-term backup storage. That's 14-21 TB right there, and that's only if we stay this size.
[... said:

If I RAID 5/6 those backup drives, it helps protect me from losing the backups, right? But if a drive fails, and I put in a new one to rebuild the array, if the rebuild process hits a bad sector then I have again lost all the versioned backups.

So do I just risk that happening, or do I have to set up a redundant backup of the NAS? Then, if one/two drives in the NAS fail, and when I rebuild the array I hit a bad sector, I just replace the drives and copy over from the redundant backup. This is what seems safest to me, but it's also the most expensive, and I guess I'm asking you guys if it's really necessary to avoid losing data. ]The reason for so much storage space is expansion potential. I could see in the next year having seven computers I would want to back up, and most computers have at least 1TB hard drives now. I allotted 2-3x the space of the hard drive for long-term backup storage. That's 14-21 TB right there, and that's only if we stay this size.
[...]
If I RAID 5/6 those backup drives, it helps protect me from losing the backups, right? But if a drive fails, and I put in a new one to rebuild the array, if the rebuild process hits a bad sector then I have again lost all the versioned backups.

So do I just risk that happening, or do I have to set up a redundant backup of the NAS? Then, if one/two drives in the NAS fail, and when I rebuild the array I hit a bad sector, I just replace the drives and copy over from the redundant backup. This is what seems safest to me, but it's also the most expensive, and I guess I'm asking you guys if it's really necessary to avoid losing data.

I was a bit reluctant to suggest this, since it adds to the complexity and learning curve. But you may want to look into ZFS. It's a redundant filesystem (as opposed to redundant disks) developed by Sun, and used in Solaris and FreeBSD. FreeNAS in particular uses it. It seems like it would solve several of the concerns you have.

- It allows over-provisioning of space. Make three 2TB volumes on a single 2TB physical array - one for each of 3 computers you're backing up. As long as the three computers don't use more than 2TB total you're good. And you can increase the physical size of the array by swapping out or adding drives later.
- It can use any type of storage - local disks, USB drives, drives on other computers, SAS drives, even files on disks (great for testing) - and glom them together to make a virtual "physical" drive called a pool. You can then put whatever volumes you want on that pool or other pools. Obviously you don't want to go crazy with this feature to maintain performance and reliability, but the flexibility is nice to have. SAS (serial attached SCSI) is particularly nice for extremely large arrays, since you're not stuck with a proprietary expansion enclosure.
- Each pool can have its own configuration. If you want one pool to have 2-disk redundancy no compression while another has no redundancy high compression, you can.
- It lets you compress volumes on the fly (which might be a reason to go with a heftier i5), which will help reduce needed physical storage space. I made one volume with the highest level of compression to test, and reads/writes at almost the same speed as my uncompressed volumes.
- Technically it supports deduplication (keeps only one copy of duplicate files, to save space). But in my tests the performance hit of that feature is huge, so I turn it off.
- Supports snapshots, so you can keep multiple versions without relying on the backup software to handle the snapshots for you.
- Provides file-level redundancy and checksums. While a two-disk failure will kill it just like a RAID (if you go with single disk redundancy), a single sector failing to read properly should not drop the disk from the array. ZFS will fix the file using the redundant copy (if you're not rebuilding), mark the sector as bad, and move on. In the case of a bad sector during a rebuild, I think it just marks the file as unrecoverable and continues. But don't quote me on that.
- It will protect against "bit rot" - automatically check files as they're read to be sure the checksum matches. If it doesn't, it will "heal" the file using the redundant copy. By default (once a week I think) it will "scrub" your pools - read every file once to make sure the file matches the checksum, and heal it if it doesn't.

The downsides are that Sun got bought by Oracle, who doesn't seem interested in developing it anymore. Most of its tools are command line only (though FreeNAS hides most of that from you). And FreeNAS has only been mostly stable in my experience. I haven't lost any data due to glitches, but I have experienced them. I'd reboot it at least once a month just to be safe. I may have some of the terminology mixed up too, since I never really got the full hierarchy between drives, pools, volumes, and datasets. All my drives are local, so the distinction is somewhat lost on me.
Anonymous
December 12, 2012 10:57:41 PM

BVKnight said:
Thanks for the replies so far.

I could build a server on my own, but once I bought the parts ($400) and the Windows Server Essentials license ($500), I've already reached the price of a NAS.


If it's just a NAS then why use Windows at all it's a little over the top, FreeNAS will do the job nicely and as the name suggests, it's free, or CentOS.

And as Solandri points out, RAID is not an alternative to a proper backup solution, and to backup your future requirements you're looking at a Robotic Tape Library or an enormous secure cloud bill.
January 3, 2013 8:52:56 PM

BVKnight said:

1. Since I'm going to be using the NAS primarily to store backups anyway, should I be worrying about RAID 5/6 for it? Does me planning on hosting shared files on it make it necessary?
2. If I use RAID, do I need to plan for double the storage amount, to backup the array itself?
3. If I do buy double the storage to backup the NAS itself, do I even need to use RAID? This might save me buying a couple drives, since I won't have the RAID overhead.

Sorry for the long post! I hope I've explained everything clearly. Thanks for any help you can offer.


Look into "FreeNAS". It is an OS that boots from a frash drive on normal PC hardware. For your use you'd need at least a 2.4 GHz i3 CPU, dual core is fine, quad if you will have many users. Then put it into a case like the Fractal Designs R4 or Coolermaser HAF that can hold 8 hard drives. Be sure and buy an Intel pro/1000 network card. They come in one, two and four port versions. get 8GB of RAM or 16 if you have many users.

Now you have for about $1,000 an empty NAS made with parts you can replace should they ever fail and it will have performance to "flood" any number of gigabit ethernet ports. Fill the box with up to 8 Western Digital Red drives.

How to organize? FreeNAS uses Oracle's "ZFS" file system it uses radiz1 or raidz2. The "z" is an improment over the more common kind but the disadvantage is the RAM requirements (8GB at least). This iwill give you an Enterprize level file surfer. If you are very concerned about reliability buy a server chassis that comes with dual power supplies and put each on it's own UPS.

Also think about how you will back up a 12 TB disk array. bout the only practical method is to build a second 12 TB array and keep them synchronized. You can do this with FreeNAS. Place one in some other building, far away and set up a VPN. You can set it up update every houror twice a day or whatever.

Info at http://www.freenas.org

You'd be nuts to spend $500 for a Windows server license when this is free and blows it away and is much simpler to set up. The ZFS is about as good as current file system technology gets

January 3, 2013 9:04:01 PM

Solandri said:
RAID is not a backup. RAID is for redundancy. Typically if there's a computer which a business needs to be up and running 100% of the time, they will RAID its disks.


Yes agree 100%. The thing that people forget is that if the probability of one drive failing is (say) 1% then if you own two drives the chance of you having a drive file is 2% In other words the more drives you own the more failures you will have to deal with. All RAID does is gives you a nicer way to deal with drive failures.

When you start working out the ways raid can fail you start wanting to back up your raid array. As it turns out drives tend to fail in pairs. So you have a raid5 system and one drive fails. The system will compute the missing data from parity but now the second drive fails and your are dead. ALL the data is gone with no way to get it back. This is really, really bad if a dozen people and your entire business is using the NAS.

Because the data on a NAS is shred and the results of failure are so bad you will need to use something like BOTH rad6 and and off-site replicated NAS to do incremental backup 24x7

You will need at least 3TB of disk space to hold each 1TB of data. So it is expensive too. But worth it if you need it.

Yes about a 3 to 1 ratio. RAID-^ uses two parity drives and then you need two RAID system, a primary and a backup.
January 11, 2013 5:56:34 PM

Thank you to everyone for the answers and information, I really appreciate it. I took some time over the holidays and since to consider everything posted here, and do a lot more research into servers and RAID. I've learned so much in the past couple weeks that it makes my head hurt thinking about it, haha!

Since so many of you suggested it, I reconsidered building our own server and figured I would test out freeNAS before doing anything else. I installed nas4free (heard it was better at transfer speeds, and had carried over the development team from freeNAS) on an old Pentium4 Dell we had lying around, just to test it out. It was easier than I thought it would be, and I could figure out how to make everything work, but at the end of the day it was still very technical. It wasn't something I would want to hand off to my successor if I knew they would have to maintain it at all, since they probably won't know much about computers or IT.

I looked into the ZFS filesystem, and it's really appealing. For a while it was what I had my heart set on, because it would obviate the data corruption issue on large drives 2TB+, and the easy snapshot backup was great. However, one of the negatives I found out for ZFS is that its Z-RAID pools are not extensible. Once I created a pool, I couldn't add additional drives later on to make that pool larger, while still having it become a part of that same pool's redundancy scheme. I would have to create a separate vdev pool with its own disks and its own redundancy, then add that to the overall storage. This wouldn't be a problem if I was creating something with a lot of space for drives, and wanted to create multiple arrays.

However, based on your answers I have reconsidered our needs and decided that we want to start small, and expand over time. I think I got carried away with my planning, and have revised my expectations (no more plans for 30+TB of data, at least not initially). So a small NAS is the way to go, and because we aren't going to be heavily transferring files I am flexible on the performance vs. the price. If I built my own NAS and used ZFS, I would have to buy all of the disks that I wanted to use in one array at once, and if I wanted expandability I would need a case with enough room for a whole other array in the future. This was too much of a start up cost, and the technical level of this approach was also a disadvantage.

BVKnight said:

1. Since I'm going to be using the NAS primarily to store backups anyway, should I be worrying about RAID 5/6 for it? Does me planning on hosting shared files on it make it necessary?

The answer to this, for my needs, is that I didn't need to worry so much about having RAID--I just needed multiple levels of backups for our files. As you have all said, RAID is not a backup.
2. If I use RAID, do I need to plan for double the storage amount, to backup the array itself? said:
2. If I use RAID, do I need to plan for double the storage amount, to backup the array itself?

I've learned a bit about backups as well. The answer was yes, I need to have a secondary plan in place in case the backups are destroyed, preferably offsite. For any original shared files stored on the NAS (no copies on any other machine), I definitely needed a secondary backup, because it would be the only backup for those particular files.
3. If I do buy double the storage to backup the NAS itself, do I even need to use RAID? This might save me buying a couple drives, since I won't have the RAID overhead. said:
3. If I do buy double the storage to backup the NAS itself, do I even need to use RAID? This might save me buying a couple drives, since I won't have the RAID overhead.

The answer to this was: probably not. For my needs, since I don't care about uptime (we're pretty flexible, and only have a service one day a week), obsessing over RAID wasn't necessary. However, I think having our drives in a RAID array for a bit of redundancy would be nice, it would make dealing with any single drive failure a little bit easier. It just won't replace the need for another set of backups.

I've decided to go with a pre-made NAS from Synology, one of their mid-range models. We probably won't get an expandable one, since it will save a few hundred $ and I've realized that by the time we need a large amount of storage we will probably want to implement a new storage model anyway (rack mount storage, maybe?). At that point we might use some of the other suggestions that were in this thread. Synology's Hybrid Raid system was a big draw, since it will allow me to expand the RAID array by adding additional drives as we go. That way I can start out with two or three disks, and add a few more later. Synology doesn't use ZFS, but I'm hoping I can install a package that will do sector cleaning on the disks at regular intervals. The accessibility of Synology's OS was the biggest factor in the decision, since I feel comfortable being able to put it in the hands of someone not a technical as me when I leave.

For backup of the NAS, I'm going to install a single license of Crashplan+ on it (not the business version). For $6/month, or $72 a year, I will get unlimited offsite cloud storage for that NAS only. Since we're not starting off with a huge amount of files, upload speeds won't be a problem. The reason I went with the personal version instead of the business one is the ability to have them send me a hard drive with my files if the NAS ever fails, and I can't afford to wait to download them. Or I may get a large USB 3 drive to back up just the NAS-hosted files, in case this happens.

At $550 for the NAS, $400 for 6TB of WD Red drives, and $50 for a UPS, I'm coming in right around $1000 for start up cost, and another $72 a year for Crashplan. For our needs and the peace of mind I have about handing it off to someone else to manage, I think it's going to work well. Now I just need to submit it for budget approval :sarcastic:  .

Thanks again for all the help, and I hope my info about our decision will help someone else in a similar situation. Special thanks to TeraMedia and Solandri, I wish I could give both of you the best answer.
January 11, 2013 8:01:22 PM

BVKnight, that sounds like a very sensible plan. I'm glad that this forum was able to provide you with some help and insight along the way. Good luck to you.
January 11, 2013 10:04:16 PM

BVKnight said:
...However, one of the negatives I found out for ZFS is that its Z-RAID pools are not extensible. Once I created a pool, I couldn't add additional drives later on to make that pool larger,...


I think you have missed one point. With a ZFS based server the thing you export over the net is a "dataset". The data set gets it's storage from the pool.

You CAN enlarge a pool. The way you enlarge a pool is to add "volumes" to it.

I typical growth plan is to start with a RAIDZ5 system that has three physcial disks. Lets say theses are 1TB drives. You would have a pool size of 2TB.

Next you decide to make it bigger, buy three more drives, make another 2TB RAIDZ then add that to the pool and now you have a 4TB pool that can service two failed drive.

The other way to "grow" the pool, that works for smaller systems is copy your data to a backup server, destory the pool and then reassemble it, then copy the data back.

What you gain with ZFS is mostly data security. Almost every other system allows for some kind of silent data corruption.

All that said, the tiping point of when to buy a NAS (like Synology) vs. when to build one happens after your fourth disk drive. I think you are better off buying an off the shelf system if you can stay within four drive bays.

As for data Security, make multiple backups and eep at least one backup far away in a different building.

One more thing: If you do buy an off the shelf unit, buy two. If the NAS unit itself fails you can't wait a week for Synthology to do an RMA you will need the on-site spare chassis. That is one other advantage of FreeNAS (or Linux) is you may already have enough spare hardware
January 11, 2013 10:23:08 PM

Thanks for the suggestions!

What you're describing with adding drives is actually the same thing I said in my post, if you remember the last part:
Once I created a pool, I couldn't add additional drives later on to make that pool larger, [b said:
while still having it become a part of that same pool's redundancy scheme.]Once I created a pool, I couldn't add additional drives later on to make that pool larger, while still having it become a part of that same pool's redundancy scheme.
[/b]
I had indeed understood that I could, using your example, create another separate RAID-Z array, and add it to the first one for combined storage. But what I was actually looking to do is add an additional disk to the original array without having to add an additional disk for redundancy. So a 1TB-1TB-1TB(redundant) array would become a 1TB-1TB-1TB-1TB(redundant) one, vs. 1TB-1TB-1TB(r) + 1TB-1TB-1TB(r). Unless I'm missing something, ZFS only has the ability to do the latter, and not the former. That was the advantage of Synology's Hybrid Raid for me.

Edit: I should clarify, I was looking for a way to do this without erasing all the data. Synology allows me to simply plug in an additional drive and go (probably with a rebuild).
January 13, 2013 5:33:23 PM

BVKnight said:
Thanks for the suggestions!

What you're describing with adding drives is actually the same thing I said in my post, if you remember the last part:

I had indeed understood that I could, using your example, create another separate RAID-Z array, and add it to the first one for combined storage. But what I was actually looking to do is add an additional disk to the original array without having to add an additional disk for redundancy. So a 1TB-1TB-1TB(redundant) array would become a 1TB-1TB-1TB-1TB(redundant) one, vs. 1TB-1TB-1TB(r) + 1TB-1TB-1TB(r). Unless I'm missing something, ZFS only has the ability to do the latter, and not the former. That was the advantage of Synology's Hybrid Raid for me.

Edit: I should clarify, I was looking for a way to do this without erasing all the data. Synology allows me to simply plug in an additional drive and go (probably with a rebuild).


The ability to add one more drive to the array is not as useful as you might think because the chassis has only either two or four bays. Obviusly you can't add the third drive to the two bay chassis. In the case of the four bay chassis there are two cases
1) you have a mirror and adding a third drive does not add to the available storage. and (2) you have a raid with three drives. Well in that case it works. But then you are "stuck" at four

The other thing is that almost certainly when your array is full you want to double it's size, not just bump it up by 20% or something

Also as you add drives to an array the chances of a failur go up. With an 8 drive array you will experience twice as frequent failures. and you want double the redundancy.

All that said, if you only need a small number of drives the smaller off the shelf units are more cost effective, unless you just happen to have a free PC with 8 bays available from a under someone's desk.
!