RAID recommendation...

[atari37]

I have an old server in a rack i'm interested in using to setup a couple of shares for our users. The server has a couple of removable/swappable drives and I'm interested in installing about 4 drives in the server.

My question is, how do I set it up so I can combined 2 300GB drives to show as 1 drive and also is it possible to use something like RAID 5 for redundancy?

I don't plan on backing up this server so I need to be able to remove one of the bad drives and replace it with a new drive without losing any data.

Help!

Can someone move this to the server 2003 forum for me?

Edited August 14, 2007 by atari37

[FAT64]

In my servers, I have 2 drives (mirrored) for the Operating System/Applications and 3 drives (RAID 5) for the data - you must have a minimum of 3 drives in a RAID 5 setup.

[Zxian]

RAID Levels Overview

You can use the built-in RAID functionality in Server 2003, but I would highly recommend getting a dedicated RAID card - even if it's a cheap one. Hardware configured RAID is (almost) always better than software configured RAID.

What kind of drives were you thinking? PATA, SATA, SCSI? What kind of demands from the users are you expecting?

[nmX.Memnoch]

Post got moved while I was replying....

You need a hardware RAID controller. If the server has removable/swappable drives then it probably already has a hardware RAID controller. You need at least 3 drives to configure RAID5. How many drives can the server hold and how many do you have? Typically when I setup a server like this I use two drives mirrored (RAID1) for the operating system, and another array for the data. The size and type of array depends on on how many the server will hold, how many drives I have and how much space is needed.

For the OS you shouldn't need anything more than a pair of 36GB or 73GB drives.

For the data, again it depends on how many drives you have and how much space you need. If you only have two drives then obviously you want to mirror them (RAID1) for redundancy. I you have three or more drives and space is your primary concern then go with a striping with parity (RAID5) setup. If you have four or more drives (and it has to be an even number) and want a good mixture of redundancy and speed then go for a striped mirror (RAID10) setup.

For example, if I had three 300GB drives and configured them in RAID5, that's 600GB of space. With a RAID5 set you always "lose" the space of one drive from the total count for the parity information...no matter how many drives you have. So four 300GB drives in RAID5 would be 1200GB - 300 = 900GB. Five 300GB drives would be 1500 - 300 = 1200GB. And so on.

However, if I had four 300GB drives I would probably configure that in a RAID10 array. That'll give you about 600GB of space. With RAID10 arrays you "lose" half the total space for parity information (the same as RAID1). RAID10 arrays use multiple RAID1 arrays striped together. This allows for some really good read/write speeds (the parity information for RAID5 doesn't have to be calculated for starters) and the ability to sustain mulitple drive failures. Each "sub" RAID1 array can lose a single drive and the array will still be operational. So if you had six drives in a RAID10 configuration that would be three RAID1 arrays striped (RAID0) together. Each of the three RAID1 arrays can lose a single drive at the same time and the array will still be operational. So you can in theory lose up to three drives at once and still have an operational array. However, if a single RAID1 sub-array loses both drives then you lose everything. BUT, with RAID5 if you lose more than one drive you automatically lose everything so RAID10, in my opinion, is the better choice for redundancy.

Most hardware RAID controllers will also allow you to configure a hot spare. This is a drive that does nothing unless another drive in an array files. The controller would then automatically assign it to an array in place of the failed drive and begin a rebuild operation to keep the array redunandant. These are mostly beneficial for RAID1 and RAID5 arrays.

Woah...that was probably too much information at once...hehe...

Edited August 14, 2007 by nmX.Memnoch

[atari37]

That's much appreciated guys.

I do have 4 300GB SCSI drives so now I have to figure out which would be the best for me, Raid 5 or 10. I've heard one good argument from nmX.Memnoch. Who else wants to chip in?

[nmX.Memnoch]

Well...there's two things I absolutely HATE doing with servers (the first is actually something I don't like doing on any computer):

1. Partition a drive or array

2. Share files from the operating system drive or array

That's why I mentioned to get a pair of small drives dedicated just to the operating system and applications.

Not only do you provide the OS with it's own redundant array, but you split up drive I/O (input/output) activity across two arrays, thereby increasing performance.

Oh...and this:

striping with parity (RAID10)

Should've been this:

striping with parity (RAID5)

I corrected it in the above post.

Edited August 14, 2007 by nmX.Memnoch

[Zxian]

My advice - listen to memnoch.

Seriously though - I would also agree that you should use a couple of independent drives for the OS and programs, and then a separate storage setup. I went with RAID5 for my home storage server, but I'm not too concerned with extremely high I/O performance, or that more than one drive would die at any one time.

Long story short - read the advice from memnoch. It's good solid advice.

[cluberti]

You also need to consider whether speed in write is important, or only read speed. RAID5 is great for read speed, but somewhat poor in write speed. If your users will be writing files to the array regularly, you need to determine whether or not speed is important to your user base doing the writes (and what kind of writes, large files or small). RAID10 is much faster than RAID5, but at the cost of more disk space to parity (a RAID5 of 4x 300GB disks gives ~900GB, whereas a RAID10 of the same gives ~600GB of storage).

[atari37]

I think Raid 5 it is...

Scenario is this. I have about 40 users on DC1 (I don't have any control over this DC) and I have about 60 users on DC2 (I have full control). My file server is on DC2 so I have full control over it. It is setup with RAID 10 and has over 3 TB of storage space (mostly shared drives).

DC1 users currently mount the shared drives on DC2 but we don't want that anymore. We want to setup a couple of shared drives on this new server, move DC1 user shares to it and add the server to DC1.

Speed is not really a factor here...I think my main goal is to get DC1 user shares off my server.

Advise to put the OS and Applications on another drive is greatly appreciated. I still have the two original 80GB drives I can use for that.

Last question. Since I'll be using hardware Raid instead of Windows 2003 built-in software, what tool do I need to complete this setup?

[nmX.Memnoch]

Last question. Since I'll be using hardware Raid instead of Windows 2003 built-in software, what tool do I need to complete this setup?

When you boot the server, the RAID controller should say something like "Press Ctrl+X to enter setup". "X" varies depending on the controller manufacture ("A" for Adaptec, "M" for older AMI controllers and some newer LSI controllers (since they bought AMI), etc). Once in the controller BIOS you can configure everything you need for the array. Most controller manufacturers also make a Windows based management utility so you can configure, monitor and manage from within Windows as well (of course, this does not good until you configure at least one array and install Windows).

I've still gotta give a strong recommendation for RAID10 over RAID5...but that's your decision and we can only make recommendations. I'm also not privy to the amount of data you're talking about either.

[atari37]

I'm also not privy to the amount of data you're talking about either.

Not enough storage? I think 900GB is plenty for what they use it for. I believe they are only using about 300GB which span from 5 years ago.

[low_tech]

Hi Atari, I'm just curious. How did you get this job/position with 3+ TB of space and 100 users, and you are asking these seemingly simple hardware setup questions?

[atari37]

Hi Atari, I'm just curious. How did you get this job/position with 3+ TB of space and 100 users, and you are asking these seemingly simple hardware setup questions?

Well, for one I'm a Unix/Linux Admin who knows enough about Windows to Administer windows boxes. We have a Unix admin and that's all he knows so I do the Windows stuff to help out. If I ask a windows question that might seem simple to you, it's because I haven't tackled that task on a windows machine before.

3TB of data is what the Windows users have and need...All other data is collected on the Unix side, sorted out and sent to the windows side for the NT users to do their work.

[low_tech]

Ah, I did not think you might be a Linux/Unix/AIX admin. Sorry bro.

[nmX.Memnoch]

I'm also not privy to the amount of data you're talking about either.

Not enough storage? I think 900GB is plenty for what they use it for. I believe they are only using about 300GB which span from 5 years ago.

I wasn't saying that RAID5 wouldn't provide enough storage. Quite the contrary actually. RAID10 will provide less storage space so I didn't know if you made your decision based on the amount of data that was going to be put on the array. If they're "only" using 300GB I still have to recommend a RAID10 configuration, which will give you 600GB of space.

My only concern is that if they're doing a lot of file writes that RAID5 would hurt performance. RAID5 is really only good if you're doing a lot of file reads. While RAID10 is fast for both reads and writes.