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Unraid NAS: Hardware Checklist

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December 4, 2008 3:45:38 PM

Looking to build a NAS using Unraid for Raid 5 with parity disk. The disks will mainly be a couple 1.5TB disks + parity for starters, with the ability to expand with more 1 or 1.5tb disks. It will house my growing collection of x264 HD files as well as critical other data like HD home videos and music.

Please let me know if this hardware will work together and any suggestions on better hardware to use for approx. the same prices:

Asus P5QL Pro (6 sata ports)
E5200 CPU
Corsair 650TX PSU (will this be enough to eventually support six sata disks? or do I need this much power? What's the min. I would need)?
Antec Three Hundred or Centurion 590 case (which one is better?)
Kingston Datatraveller 2GB USB (for the Unraid OS)

Drives wise, I currently have a 1.5TB Seagate 7200.11 which I understand I probably shouldn't use due to freezing issues.

What large (at least 1TB) are the cheapest/most reliable to use for this RAID 5 NAS?
December 5, 2008 12:34:37 AM

Anyone want to weigh in on this?
a c 82 G Storage
December 5, 2008 12:57:01 AM

The PSU exceeds the requirements (assuming that you'll use a low power video card as we normally use in servers). A good 450 watts PSU should be plenty.

As for hard drives, I'd certainly consider the new Western Digital Caviar Black WD1001FALS 1TB.

Select the case that can best keep your hard disks cool. A front fan blowing on the disks should keep them cool enough.
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December 5, 2008 1:43:12 AM

Agree with ghislaing

Those specs are more than enough... ive got a quad core running 10 HDD with a 650w psu.

The WD blacks are some of the best out there ATM
December 5, 2008 2:37:02 AM

I already own one of the suspect 1.5TB Seagate Barracuda's. Do you think it would still be ok to use it as the parity drive in the Unraid NAS, with the remainder of the disks being WD Blacks? Or should I avoid having it in there at all (more expensive)?
a c 82 G Storage
December 5, 2008 2:46:59 AM

Since it's a software RAID, you could certainly use it. You could buy more Seagate 1.5TB drives, but I prefer WD drives.
December 5, 2008 3:06:39 AM

Oh I see, so the Seagate freezing issue only happens with hardware raid then? Got it. I might as well get more Seagates then because they are cheap as hell.
December 5, 2008 3:12:54 AM

Apparently it doesnt happen in Microsoft OS's either (from what ive heard) Linux and Apple are effected
December 7, 2008 11:32:14 AM

I only use Seagate ES.2 Drives. WD RE3 Drives when these aren't available.

I build CCTV- DVR's And mass storage for these systems. I've never had either of these drives fail... (30 cam 30fps 24/7 workloads)
The Drives are rated 1,000,000 MTBF and have 5 year warrenties

Overkill on the PSU but more is definately better than not enough..

Cooling is definatley a top priority Hard drives tend to generate lots of heat so your case should provide plenty of airflow, at least 2 fans (one front and 1 back)

I wouldn't chance installing the RAID system on a USB drive. I have experianced way tooo many failures with these things.

my opinions..

Jay
December 7, 2008 2:14:54 PM

What do you recommend? Windows Home Server? Does that do RAID 5?

Or would FreeNAS be better?

Either way, I really just want to protect my data and have it available on one uniform location. As long as it can transfer the data fast enough to not hiccup HD media playback on a HTPC connected on the LAN, then I don't need more speed than that.

Suggestions?
a c 82 G Storage
December 7, 2008 2:32:55 PM

If you're already familiar with other Microsoft Operating Systems, Windows Home Server might be easier to setup/configure.

How will you backup your server? You shouldn't assume that you'll never experience a catastrophic RAID failure and lose all of your data.
December 7, 2008 4:09:10 PM

GhislainG said:
If you're already familiar with other Microsoft Operating Systems, Windows Home Server might be easier to setup/configure.

How will you backup your server? You shouldn't assume that you'll never experience a catastrophic RAID failure and lose all of your data.



Listen, I didn't want to get into anything to elaborate (read: expensive). Unraid or even FreeNAS (what's the differences?) seems to do everything I want for essentially the cost of the hardware only for a basic PC.

If I decide to go the Windows Home Server route, are you saying now that I need to build a whole other machine just to back that up?
a c 82 G Storage
December 7, 2008 4:31:50 PM

FreeNAS (if you're somewhat familiar with FreeBSD or Linux) is fairly easy to setup/configure. Windows Home Server, which isn't free, is very easy to configure.

FreeNAS offers more options and is better known, at least for me, than Unraid (I admit that I never heard of it before). Since both are free, download them, give them a try and use the one that best meets your requirements.

How important are the files that you'll store on that server and does it matter if you lose them?. If you answer no, then a backup solution is not required. If you answer yes, then you should consider some backup solution (an external USB disk, burn important files to DVDs, upload them to an online backup site, etc.) just in case you lose the RAID. As many members have said before, a RAID is NOT a backup solution. It's usually better than a single disk, as long as RAID0 isn't used, but don't assume that it'll never fail.
December 7, 2008 5:14:54 PM

FreeNAS is based on FreeBSD and features geom_raid5, a software RAID5 engine with writeback and I/O combining support. Although FreeNAS has been using an older (but stable) version of geom_raid5, a newer version is able to achieve blazingly fast speeds (400MB/s+ with 8 disks) with low-end modern hardware ($35 amd dualcore). No linux solution or RAID-Z offered by the ZFS filesystem is able to beat this. Its sequential performance is about the same as an Areca-ARC1220 hardware RAID5 controller with the same disks.

So if you want Software RAID5, i highly recommend FreeNAS or FreeBSD, while discouraging the use of Windows, unless you are willing to spend some big bucks for a good controller. Intel ICHxR RAID5 might be the only driver RAID solution with acceptable (but still mediocre) write performance.

Also read what ZFS can do for you, checksums, self-healing, compression, dynamic pools, raid-z, it's all there! Soon to be in FreeNAS too. :) 
December 7, 2008 6:19:24 PM

GhislainG said:
FreeNAS (if you're somewhat familiar with FreeBSD or Linux) is fairly easy to setup/configure. Windows Home Server, which isn't free, is very easy to configure.

FreeNAS offers more options and is better known, at least for me, than Unraid (I admit that I never heard of it before). Since both are free, download them, give them a try and use the one that best meets your requirements.

How important are the files that you'll store on that server and does it matter if you lose them?. If you answer no, then a backup solution is not required. If you answer yes, then you should consider some backup solution (an external USB disk, burn important files to DVDs, upload them to an online backup site, etc.) just in case you lose the RAID. As many members have said before, a RAID is NOT a backup solution. It's usually better than a single disk, as long as RAID0 isn't used, but don't assume that it'll never fail.


Wouldn't running Unraid (RAID5 sort of with parity) pretty much prevent me of data loss unless two HDDs fail at the same time? I mean, I wouldn't even build a NAS with RAID unless it was to AVOID having to mirror data either on another HDD or on optical disk.

Unraid seems to give me that, with the scaling ability to grow the array.

So you are saying that I shouldn't rely solely on a system built specifically for redundant fault tolerance?

Performance wise, as long as it can have HD files played back across a LAN from it on a HTPC, than I don't care about if it transfers at 20MB/s or 400MB/s (i.e. I'll suffer through the copy speeds.
December 7, 2008 6:43:33 PM

I don't know Unraid, i only know FreeNAS/FreeBSD and in particular its raid5 driver named geom_raid5, by which i was involved in its development in particular testing and benchmarking.

Sorry if this is going to sound technical: RAID5 involving a write-back mechanism, without the use of strong journaling, will always present the risk of filesystem corruption in the case of a crash, power issue, overheating or an unclean shutdown. The data that is written and should be on the physical hard drives is actually still residing in the RAM memory, and will be lost.

The results depend on how good your filesystem is with coping with lost writes. NTFS uses "weak" metadata journaling, which is excellent for the write buffer found in all modern hard drives, which also say data is written while its still in their onboard RAM chip and will get lost if they unexpectedly loose power. NTFS can cope with that, but it cannot cope with large portions of writes missing, and writes being issued in the 'wrong' order.

Hardware controllers with onboard memory often allow you to use a Battery Backup Module (BBU) which will keep supplying power to the onboard memory in the case of an emergency. And due to it being Hardware RAID, it works independently from the Operating System so in the case of a crash, a press on the reset button etc, the RAID engine keeps working and keeps holding the data stored and keeps writing them out of disk, even as your PC is rebooting after the reset.

So, this is the protection Hardware RAID can give you to the problem of filesystem corruption on write-back mechanisms. What? Write-back means you lie when you say data has been written to disk, while in fact you store the data in a buffer (like your RAM or onboard memory chip). The data in this buffer is lost when power is lost. And the contents in the RAM are lost when the system crashes/freezes/hangs/etc. Also, bugs in Windows shutting down too early also caused many problems in the past. Conclusion: RAID5 alone is not enough 'protection' against data loss. As a sidenote, it has caused me to loose data in the past.

If you want to use Software RAID5, you can limit the risk of filesystem corruption in the cases described above by the use of either strong or smart journaling. This lowers the write performance for large files because all data has to be written twice to the storage device.

ZFS uses the ZIL (ZFS Intent Log) to keep track of what it was doing so after a crash the situation can be recovered without loss of data, only going back in time to a situation like 30 seconds before the crash. This is possible due to the Copy-On-Write model ZFS uses. The only downside is privacy since zero-writing your files no longer removes all traces of the data and could be recovered by manual intervention.

On FreeNAS, you can use geom_raid5 for the RAID5 and put a journal on it called geom_journal. This is strong journaling and should offer a formidable protection against lost buffers. Just make sure to make the journal large enough for the maximum speed (not size) your array can take. 2GB journal size should be adequate for a small array. This space will be unavailable for file storage.

So, with both software RAID5 and hardware RAID5 you can be safe, but not without carefully configuring your systems. And even then there are risks:
- fire melts your disks to a nice glue
- you cause the computer case to drop sideways causing a head crash on multiple hard drives -> byebye parity protection
- a virus destroys your data (*)
- you accidentally delete files (*)

(*) preventable by using snapshots. ZFS is great for this, it can maintain a history of your files allowing you to browse 'back in time' without storing data multiple times. It simply stores the changes since the last snapshot. A snapshot is like a 'photograph' of the current data stored on a volume. It is comparable to the System Restore functionality in Windows.

Good luck ;) 
a c 82 G Storage
December 7, 2008 6:56:27 PM

A lot could happen: a major system failure can make your hard disks unrecoverable, the system could be stolen (unless it's in a secure place), files could be erased by error, etc. If you were using a RAID1 or a RAID10, then you'd be a bit safer, but still not immune to a potential data loss. I'm just trying to make you fully aware that RAID is not a backup solution - it can only be a reliable storage solution.

At a minimum make sure that you use a good UPS that will bring shutdown the system should an extended power failure occur. That will also protect your system from power anomalies, etc. I run servers at my place, but they are backed up on a regular basis and I have a couple UPS to protect them.

The copy speed won't be a problem, unless you have a very slow LAN.
December 7, 2008 7:17:00 PM

You do not need a UPS with journaling or a BBU installed, though it can prevent headaches and even dangerous mistakes.

Just think about what you do not want to loose, your personal photos your documents, most of that stuff isn't that big. Stuff that can be re-downloaded, might not be important enough to need a backup. An easy solution is to use a big (1TB WD Green) drive on a regular desktop system as a backup and copy files over the network manually or using some synchronisation software (like rsync, which comes with FreeNAS). This allows you to backup the stuff you really don't want to loose on a single drive in a different computer system and preferably in another room in case of fire. A home situation is often ideal for this simple backup solution but still very effective.

Another solution is to use eSATA/USB external harddrive and store in a safe or something, or to simply burn your personal files to DVDs. Note that home-burned disks have a risk of bit rot (love that word) because the layers on the dvd disk react chemically and don't have the same lifespan as a commercially produced DVD-ROM.

But gjislaing is right, RAID is no backup - its redundancy. It offers no protection at all against risks a backup can protect you from.
December 7, 2008 8:52:59 PM

Thanks for the great info. As you can tell, I'm not an expert at this stuff.

I noticed that my HTPC's mobo is a Asus P5B-E, which has a JMicron and ICHT or something RAID controllers capable of 1, 5, and 10 RAID formats.

I'm wondering if I just can't configure my three 1.5TB + 1 320GB and 1 120GB drive (5 drives total) in RAID 1 or 5 (still confused on these) to provide me with the fault tolerance I need right in my HTPC using the hardware RAID that exists in the mobo and still use my HTPC for what's it's meant for.

Any thoughts on that?
December 7, 2008 8:54:26 PM

GhislainG said:
A lot could happen: a major system failure can make your hard disks unrecoverable, the system could be stolen (unless it's in a secure place), files could be erased by error, etc. If you were using a RAID1 or a RAID10, then you'd be a bit safer, but still not immune to a potential data loss. I'm just trying to make you fully aware that RAID is not a backup solution - it can only be a reliable storage solution.

At a minimum make sure that you use a good UPS that will bring shutdown the system should an extended power failure occur. That will also protect your system from power anomalies, etc. I run servers at my place, but they are backed up on a regular basis and I have a couple UPS to protect them.

The copy speed won't be a problem, unless you have a very slow LAN.



Gotcha. Thanks for the added advice. I see your points.
a c 82 G Storage
December 7, 2008 10:30:08 PM

You can't use ICH9R unless you run some flavor of Windows (Vista, Home Server, Server 2003 or Server 2008).

You could use your 120GB disk as the boot drive and setup the other 3 disks in a RAID5 configuration. For RAID1 or RAID10, you always need an even number of drives (2, 4, etc.) All hard drives in an array should be the same size.
December 7, 2008 11:12:19 PM

If I used the onboard ICH8R on my mobo for RAID 5 (with parity) as follows:

C: Boot drive and system drive (non-raid) = 120GB
D: disk 1 in raid 5 array = 1.5TB
E: disk 2 in raid 5 array = 1.5TB
F: disk 3 in raid 5 array = 1.5TB

Firstly, as I understand it (please correct me if I'm wrong), this will give me one large area of drive space for data totalling 4.5TB?
Or will it give me only 2.25TB with the other 2.25TB used for parity?

Secondly, if one of the physical drives fails, will I lose all the data in the RAID? Or could I swap out the faulty disk and still rebuild all the data? THis is actually my most critical point, as unRAID will allow me to do this.

Lastly, would this setup allow me to add another 1.5TB drive as G: and thus in effect expand the RAID 5 (with parity) array? Again, unRAID lets me do this.


I'm trying to weigh this solution against building a completely separate NAS device running either Windows Home Server or ideally unRAID.

Final bit of information: While my absolute critical data totals only about 200GB, I have about 1TB worth of data that I really would hate to have to redownload in the event of a failure. So sure, I could replicate that critical data ( and will now after your advice) onto DVDs and other HDDs, I don't want to do that with all of the 1TB (which by the way continues to grow monthly...mainly x264 HD movie files).
Lastly, I just bought a HD camcorder so the AVCHD files I'd also like to archive, and will be also deemed as critical data (kids movies).
a c 82 G Storage
December 8, 2008 12:45:52 AM

3 x 1.5TB in a RAID5 configuration will provide 3TB of storage. Parity will be striped across all 3 drives using the ICH controller or on a single drive with unRaid.

If one drive fails, you replace it and rebuild the array. You won't lose data, unless another drive fails while rebuilding the array. Unfortunately it usually is when drives fail because they temporarily are very busy.

If you need online expansion, then your solution is unRaid.

All drives in a RAID appear as a single physical drive to the operating system. Not all operating systems can handle a volume size larger than 2TB , therefore you'll most likely have to split the array and create 2 partitions (D: and E:) .
December 8, 2008 12:50:27 AM

On RAID5 the capacity of one disk is lost to parity data, so cannot be used to store files. So simply don't count 1 disk, and add up the numbers. In your case thats 1.5 + 1.5 = 3.0TB = ~2.66TiB of usable capacity on the RAID5 volume when using 3 disks.

Should you use 20 disks, you still only loose 1 disk to parity so you can use the capacity of the other 19. Thus, the percentage of unusable space is much lower when you have more disks in your array.

On your second question, RAID1,0+1,10,3,4,5 and 6 will all protect you from at least one hard drive failure, with the ability to recover from that situation by replacing the faulty disk with a new one. This should be supported by any RAID implementation. Only RAID0 is an exception, since it provides no redundancy or protection against data-loss by drive failure. Some like to call it AID0, with the R from Redundant omitted.

The only thing you cannot easily do, is add more disks to an existing array, preserving your data. This is an advanced and complex procedure only supported by most serious hardware RAID controllers and a handful of software RAID implementations. I've written a program that should allow adding disks to a FreeNAS RAID5 array, but its not in a fully working condition yet. If unRAID offers this functionality, it's certainly a plus.

ZFS doesn't yet support adding disks to a RAID-Z array, that's the name they use of their tweaked RAID-5, where with normal RAID-5 the stripe size is always the same, with RAID-Z the stripesize is dynamic, which makes random writes much faster.

Regarding your backup: just make sure you are having a proper backup for your personal and professional stuff you'd not want to loose. I use multiple NAS systems which act as periodic backup (nightly & monthly), using various filesystems and configurations. This should provide a formadible protection against data-loss, but comes at the cost of high initial cost and a lot of work for you to configure everything to a workable solution. If you want to follow such a road, i'm happy to help you. But you have to decide how important your data is and how much you are willing to spend for its protection.

Personally, i've used RAID0 in the past with making the mistake of also storing important personal files on it, which got lost once a disk broke. I'm just hoping other people won't make the same mistake which could have been easily prevented: seperate your personal stuff from bulk stuff (things you download) and think about how to best protect your data within your money constraints.
December 8, 2008 2:01:01 AM

Thanks to both of you for your information. I think I'm going to build an unRAID server as mentioned above, and also backup all of the absolute critical stuff to DVD.

Within my cost constraints that is the best way to protect my most precious data, while also allowing for some redundancy and fault tolerance for stuff that would be a pain to reacquire.

Thanks again.

!