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eSATA Storage/Backup Solution

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August 14, 2006 5:33:18 AM

Disclaimer: I am very much a RAID noob, so be gentle... :roll: And to make this post as easy to read (and respond to) as possible, all my questions are in blue!

The Objective:
To have a cheap, reliable and (relatively) fast way to backup and store video, music, pictures, and basically anything else that you don’t want to lose. Also it would be nice, but not required, to be able to capture video directly to the system as well. This will be connected to a W2K SP4 machine.

The Plan:
I’ve been looking for an enclosure to put in (4) SATA II, 250 – 300 GB drives. What I’d like to do is set this up as RAID 0+1. I have a lot of family pictures and video, as well as my music collection that need to be securely backed up. I also do a lot of video editing, so I’m hoping to use a part of this as a working drive as well. Because of past HD failures and loss of data, I’m paranoid of losing any other data. And from what I’ve researched, a RAID 0+1 would be my best option. Agree, disagree? How would I go about setting something like this up on a W2K machine? I’ve setup a simple 2 drive RAID 0 before, but never attempted a setup like this. Any tutorials out there?

The Questions:
In my research, eSATA seems to be the way to go. If so, I would need to get a controller card for my system. It would have to be PCI, as my board’s PCI-E slots are currently occupied with a SLI setup. Will I be missing out on speed because of the PCI?

As far as the actual enclosure, I’m looking at this storage tower solution from Addonics. The one that caught my eye was their ST5X1PM model because it includes a Port Multiplier? This totally seems to be the way to go. If I can connect these 4 drives up by a single cable, I’d be a very happy person. But the question is, is there a loss on performance? Anyone else have experience with a PM?

I was looking at this for my host controller. It’s PCI, SATA II Compliant, but in this article it doesn’t say it works with a RAID 0+1 configuration. However, on the multiplier link (above) it says “Drives can be configured as RAID 0, 1, 0+1, 5 or JBOD when connect to one of the Addonics RAID5 controllers with PM support”….and it shows this controller as one of those. What am I missing? Can anyone confirm if this is going to work for me?

What enclosures have you heard about or are using yourself? Why would this Addonics system be a bad choice? What would be a better choice?

Any other aspects I should be concerned about?

Thanks in advance for your help guys. I'm new posting here but I have used this site as a reference guide, countless times in the past. I know this is where the experts live. :D 
August 14, 2006 6:34:16 AM

Sound to me that a Raid 0 is the best way for you. Anyways what kind of motherboard are you using? Does it have an onboard raid controller? Anyways raid 0 is the cheapest and easiest way to implement, although not fault tolerant for one corrupt/damage drive will render the whole array useless. That is why you need to have a backup storage for your files, music, pics and etc. Like me I have 2x74Gb Raptor in raid 0 and one 300Gb for backup and storage.

Raid 0+1 Disadvantages:

A single drive failure will cause the whole array to become, in essence, a RAID Level 0 array. Very expensive / High overhead. All drives must move in parallel to proper track lowering sustained performance. Very limited scalability at a very high inherent cost.
August 15, 2006 4:04:05 AM

As far as the RAID configuration....a firend at work, who has a little more experience with different RAID configurations, suggested I go with RAID 5. This would allow me to use a larger portion of the 4 disks, yet still have the backup in case a single drive should fail. I think this is what I'm going to go with.

I still have questions though on the Port Multiplier. Does anyone have experience with using one? Also, what other eSATA solutions have you used? What are things I should consider when putting a system like this together?
Related resources
August 15, 2006 4:29:31 AM

Well this my first raid and currently I have 2x74Gb Raptor in Raid 0 (typical gamer's raid) and another 300Gb for backup. I have over 100Gb of musics and some pics and important stuff too. The raid is mainly for my os and games while the rest are in the backup/storage disk. I also have an old pc which is now my file server to keep important documents and what not.

Raid 0 is the cheapest and easiest way you can raid and eventhough it's not secure compare to other raid. Raid 5 is very high performance and very complex as well. Well if you can afford for raid 5 then it's the way to go, it's faster than raid 0 and more fault tolerant. If one disk fails in raid 5 it would have a medium impact to the array and it is difficult to rebuild but data and array can be recovered nontheless.

Well since you haven't done it I think you should do it. But it needs a good controller to fully take advantage of raid 5 performance. As for raid controllers, sorry I can't help you there. And as for the port multiplier, no I have no experience with that feature. Sorry.

Whatever you go with either raid 0+1 or raid 5, let me know hows the performance. OK.
August 15, 2006 6:46:17 AM

Quote:

The Objective:
To have a cheap, reliable and (relatively) fast way to backup and store video, music, pictures, and basically anything else that you don’t want to lose. Etc...

The Plan:
What I’d like to do is set this up as RAID 0+1. ... Etc... Because of past HD failures and loss of data, I’m paranoid of losing any other data. And from what I’ve researched, a RAID 0+1 would be my best option. Agree, disagree?


I think there is a better option than RAID 0+1. RAID 0+1 means that you are mirroring (RAID 1) a striped set (RAID 0). This combination requires 4 hard drives and it is not the one that offers you the most reliability (which from your comments, I believe you'd like to achieve). In RAID 0+1, the failure of any one drive degenarates the entire array to a RAID 0 array, at this point, any problem in any of the remaining 3 drives could easily mean the total loss of your data.

You can achieve greater reliability with only 3 drives setup the following way,

:arrow: 2 drives configured as RAID 1.
:arrow: 1 additional drive (the third one) as a stand alone drive.

With that configuration, you have the simplicity and reliability of RAID 1. The third drive I would use to backup (image using ghost) the RAID 1 array. The frequency at which you'd backup/image the RAID 1 array is up to you but, backing it up as seldom as once a week would be reasonable since you'd have to lose 2 drives simultaneously in order to lose 1 week's worth of data.

There are other reasons why I'd pick this setup over RAID 0+1 or RAID 5. I'll mention the reasons as I answer your remaining questions.

Quote:

The Questions:
In my research, eSATA seems to be the way to go. If so, I would need to get a controller card for my system. It would have to be PCI, as my board’s PCI-E slots are currently occupied with a SLI setup. Will I be missing out on speed because of the PCI?


I think your choice of eSATA is good. Disclaimer: I have not had a chance to work with eSATA yet but, given its specs and, your limitation of using a PCI card, no better alternative comes to mind as it will certainly be a lot faster than using USB2 or Firewire. Better solutions would have been available had you had a PCI-X or PCI-e x16 slot available. eSATA is the only solution I see available to you that will give you a decent amount of bandwith (127MB as it will be constrained by the PCI bus)


Quote:

As far as the actual enclosure, I’m looking at this storage tower solution from Addonics.


I have not worked with that enclosure. As far as that goes, I recommend you look on the net for reviews.

Quote:
because it includes a Port Multiplier? This totally seems to be the way to go. If I can connect these 4 drives up by a single cable, I’d be a very happy person. But the question is, is there a loss on performance? Anyone else have experience with a PM?


Depending on the communication protocol used by the host controller you can have a noticeable performance degradation. Read this for a better explanation than I can provide here,

http://www.sata-io.org/portmultiplier.asp

Obviously you want to purchase an FIS based host adapter.

Keep in mind that the true limitation is going to be the PCI bus. That will limit you to 127MB/s no matter what. This is one of the reasons that I would not go with a RAID 0+1 or RAID 5 array. The more drives the host adapter has to communicate with, the larger the performance hit is going to be, since more data has to be sent down the 127MB/s link. A simple RAID 1 can work very well with 127MB/s bandwith, the same cannot be said of RAID 5 and much less of RAID 0+1. In addition to that, you have to take into account that RAID 5 in particular means a lot more work for the controller. If you want to keep the cost of the controller reasonable, an inexpensive RAID 1 controller will do a great job due to the simplicity of RAID 1. An inexpensive RAID 5 controller is unlikely to offer good performance because RAID 5 is significantly more demanding on the controller than RAID 1.




Quote:

I was looking at this for my host controller. It’s PCI, SATA II Compliant, but in this article it doesn’t say it works with a RAID 0+1 configuration. However, on the multiplier link (above) it says “Drives can be configured as RAID 0, 1, 0+1, 5 or JBOD when connect to one of the Addonics RAID5 controllers with PM support”….and it shows this controller as one of those. What am I missing? Can anyone confirm if this is going to work for me?


I recommend you get the answer to that from the horse's mouth. Once you know the kind of setup you want, contact the manufacturer and ask them for what they would recommend. If they recommend different hardware than what you had in mind, submit to them what you thought and ask them what their opinion is. Let them give you a little bit of education (and consulting) about their products.

Quote:

What enclosures have you heard about or are using yourself? Why would this Addonics system be a bad choice? What would be a better choice?


I cannot help you on this one. I have not used Addonic's products before.

Quote:

Any other aspects I should be concerned about?


Yes, keep it simple. I think your original plan is too complicated, potentially too expensive and, ultimately not what will give you the best performance and reliability.

Quote:

Thanks in advance for your help guys. I'm new posting here but I have used this site as a reference guide, countless times in the past. I know this is where the experts live. :D 


I hope you found this helpful.
August 15, 2006 7:00:59 PM

440bx,

Thank you so much for your detailed response. I still have a question though about the RAID setup using the 2 drives as RAID 1. Let's just say all the drives I use are 300GB, and let's just say the drives stay that size, even though I know part of the drives get used for "RAID Stuff". With the configuration you're suggesting, how much "usable" disk space would I have available? Would that be 300? RAID 1 being mirroring, is that now mirroring the "primary" 300? And if "secondary" is mirroring the "primary", what is the 3rd drive doing? Can you tell I'm confused? :D 

You'd also have to lose 2 drives simultaneously to lose the data in a RAID 5 configuration correct? I'm not that concerned about speed, as I said initially, I'd like a "relatively fast way". What a really want is something big, and reliable. If it takes 10 minutes to copy 30GB of data (for example) so be it. I'll probably have these backup jobs running in the middle of the night anyway.
August 16, 2006 1:52:01 AM

Quote:
440bx,

Let's just say all the drives I use are 300GB, and let's just say the drives stay that size, even though I know part of the drives get used for "RAID Stuff". With the configuration you're suggesting, how much "usable" disk space would I have available?


With the configuration I suggested, you end up with 600GB of usable space as shown below.

:arrow: 300GB from the RAID 1 array (half the 600GB usable)
:arrow: 300GB from the 3rd drive which is not part of any RAID array.

RAID arrays don't create a drive hierarchy, therefore from the viewpoint of the RAID controller there is no primary or secondary. Both drives are "peers" (equals).

In this setup, for you to lose all of your data you need to lose all three drives. This presumes that you are using the third 300GB to further backup the RAID array using Norton Ghost (for instance.)

Quote:

You'd also have to lose 2 drives simultaneously to lose the data in a RAID 5 configuration correct?


Yes, in a RAID 5 configuration that uses 3 drives, you'd have to lose 2 of them to completely lose all of your data. In the setup I suggested, if you lose 2 drives, you still have not lost all of your data (presuming you are using the third drive to store backup images of the RAID array)

It is also very important for you to understand that even though you may be able to setup a RAID 5 array, there will be significant downsides to it, namely,

1. A good RAID 5 controller is expensive and you will need one in order to attain decent performance.

2. You should really buy TWO (2) RAID controllers because RAID controllers are NOT interchangeable. If you have a controller failure, you cannot simply stick your drives onto any other RAID 5 controller and expect things to work, they won't. You need the exact same controller to be guaranteed recovery from a controller failure (they are rare but they do happen)

Quote:

I'm not that concerned about speed, as I said initially, I'd like a "relatively fast way". What a really want is something big, and reliable. I'll probably have these backup jobs running in the middle of the night anyway.


Stick with RAID 1 (mirroring) and perform a backup of it onto the 3rd drive. This is a simple setup that will give you good performance, is easy to understand and maintain and, very cost effective.

Keep in mind too that you can easily use this setup without incurring into the expense of an external storage unit. The three drives can easily be housed in your computer case.

You may want to consider a setup similar to mine. I have all my drives installed in removable enclosures, the host frames are attached directly to the PC case. That way, I can replace a drive, literally, in a matter of seconds (less than 15 seconds if you have your spare drives ready).

I suggest you take the time to read the following articles,

http://www.tomshardware.com/2002/08/13/ide_training_cou...

http://www.tomshardware.com/2002/08/30/ide_training_cou...

http://en.wikipedia.org/wiki/Redundant_array_of_indepen...

For desktop only application, the following is an interesting option,

http://www.tomshardware.com/2003/11/28/kill_scsi_ii/

Finally, RAID can be implemented without a RAID controller entirely within Windows. It has significant advantages (one being no RAID controller dependence). Find the details at,

http://www.tomshardware.com/2004/11/19/using_windowsxp_...

In the above article, Windows XP is hacked to provide capabilities that are normally found only in the server editions. I'd rather have a clean server edition to do this than risk having a Windows update affect the hack.

Last, lookup "mirrored volumes" in the "run->help and support". There are some very good comments there.

EDIT: not "run->help and support" but "START->help and support" then type "mirrored volume" and search.

The above articles will enable you to better understand the foundation on which my suggestion rests.

HTH.
!