Raid 5 on Windows Server 2003

jbaello

Hello everyone, I am trying to find a simple instructions on how to configured Raid-5 on software based Windows Server 2003, I usually configure this via a Perc controller, but one of my Poweredge 1800 and 2650 does not have a Perc card, I will configuring a separate Edge transport and possibly ISA in the future.

Also I am only used to backing up AD stuff via ntbackup etc., is there any other way to backup AD stuff in a more simpler fashion?

Thanks

dynamik

You're talking about the software raid in Server 2003?

There's really nothing to it: http://technet2.microsoft.com/windowsserver/en/library/ce9e738d-d94a-4127-849c-903576fb07df1033.mspx?mfr=true

Just convert 3+ disks to dynamic and start the new volume wizard on one of them.

You can get 3rd party backup software that does much more than ntbackup.

sprkymrk

jbaello wrote:

Also I am only used to backing up AD stuff via ntbackup etc., is there any other way to backup AD stuff in a more simpler fashion?

Thanks

If you just want to backup your GPO's manually you can do that from the Group Policy Management MMC. Right click on the GPO you want to back up, select backup and follow the prompts.

jbaello

Cool thanks

astorrs

While it's not simpler it's definitely a lot cooler to use an Active Directory agent for Backup Exec/NetBackup/etc. The granular restore capability without having to resort to authoritative DC restores can pay for the cost of the agent in a single use.

HeroPsycho

What exactly are you using for RAID5?

Is this for a DC?

If it's strictly a domain controller, you absolutely don't need RAID5. A RAID1 mirror would be the better way to go.

To "Backup AD", it really depends how you want to restore it. If it's to restore to a working DC state again, you need a backup program that natively understands AD. That would mean NTBackup, or BackupExec/NetBackup, etc.

astorrs

HeroPsycho wrote:

What exactly are you using for RAID5?

Is this for a DC?

If it's strictly a domain controller, you absolutely don't need RAID5. A RAID1 mirror would be the better way to go.

I believe those were two separate questions. Sounds like he wants to do a RAID5 on an Exchange Edge Transport on some older Dell hardware. I would echo Hero here though, I would stick with RAID1 unless there is a reason why you need additional storage/spindles.

HeroPsycho

Yeah, I can't think of a good reason for RAID5 on a Hub Transport server. Rapid writing to queues would perform much better on RAID1 than 5.

jbaello

It just happened that each of the Poweredge had 3 SCSI HD, the backup part I just need something very simple atm, since I just wanted to save AD Objects, whenever I crash and burn a DC. Eventually I will come up with a more robust AD backup utility, since I will be hosting some email for live use.

dynamik

jbaello wrote:

It just happened that each of the Poweredge had 3 SCSI HD, the backup part I just need something very simple atm, since I just wanted to save AD Objects, whenever I crash and burn a DC.

Whenever?

Does it happen that often?

astorrs

For the RAID thing, I would just pull one of the drives and do a RAID1 mirrored set. Less chance of failure and better write performance for that role.

For the backups I think the best you can do is a system state only backup using NtBackup.

jbaello

dynamik wrote:

jbaello wrote:

It just happened that each of the Poweredge had 3 SCSI HD, the backup part I just need something very simple atm, since I just wanted to save AD Objects, whenever I crash and burn a DC.

Whenever?

Does it happen that often?

Lol with M$ yeah :P I'm starting to think of imaging this DC...

astorrs

jbaello wrote:

Lol with M$ yeah :P I'm starting to think of imaging this DC...

That's a really scary idea. Bringing a DC up that's been offline for a few weeks/months can be "exciting" to say the least.

If you're really worried about it and have to do it on a regular enough basis to consider imaging it (which probably means there is something unhealthy in the environment), why not automate the build process for a new domain controller. Assuming you have another DC on the same LAN segment rebuilding it from scratch including syncing the directory should take an hour or two at most.

HeroPsycho

astorrs wrote:

For the RAID thing, I would just pull one of the drives and do a RAID1 mirrored set. Less chance of failure and better write performance for that role.

Or RAID1 with a hot spare. Better performance and better redundancy than RAID5 in that scenario...

sprkymrk

HeroPsycho wrote:

astorrs wrote:

For the RAID thing, I would just pull one of the drives and do a RAID1 mirrored set. Less chance of failure and better write performance for that role.

Or RAID1 with a hot spare. Better performance and better redundancy than RAID5 in that scenario...

Actually RAID 1 takes a small performance hit with writes, but is generally faster on reads. RAID 5 does take a perormance hit due to calculating an extra parity bit every third (depending on the number of drives) time. I don't know that the difference will be significant either way. Also not sure why RAID 1 would have less chance of failure? RAID 5 will also give you a lot more storage.

EDIT - Just noticed he might be talking about software RAID. Yes, lots of overhead with RAID 5 on that, so it might come down to a storage issue. Also, I doubt he can do a RAID 1 with a hot spare in software. Needs the Perc controller for that methinks.

astorrs

sprkymrk wrote:

Actually RAID 1 takes a small performance hit with writes, but is generally faster on reads. RAID 5 does take a perormance hit due to calculating an extra parity bit every third (depending on the number of drives) time. I don't know that the difference will be significant either way. Also not sure why RAID 1 would have less chance of failure? RAID 5 will also give you a lot more storage.

EDIT - Just noticed he might be talking about software RAID. Yes, lots of overhead with RAID 5 on that, so it might come down to a storage issue. Also, I doubt he can do a RAID 1 with a hot spare in software. Needs the Perc controller for that methinks.

Note: I'm assuming we're using 10K SCSI disks here due to the age of the servers, and am therefore using an IOPS of 140 per disk at the controller (15K would be 180).

RAID-1 has a write penalty of 2 as each block needs to be written to both disks so for RAID-1 writes the calculation is as follows:

# of disks * IOPS per disk / 2

or 2*140/2 = 140 IOPS or the same as a single disk

For RAID-5 which has a write penalty of 4 due to the need to read parity, read the data, (calculate the parity), write the parity, write the data, the calculation is:

# of disks * IOPS per disk / 4

or 3*140/4 = 105 IOPS

So the RAID-1 set will have 33% better write performance. Keep in mind these calculations don't factor in the percentage of reads vs. writes; only the writes are penalized for IOPS and reads on a RAID5 set will benefit from the extra spindles.

The cache on a controller will often help mitigate the penalties involved, but in a software only RAID solution they will be right there in front of you. Also the CPU will have to do the "calculate the parity" step vs. a dedicated RAID controller and that will slow things down a little more.

The MTBF will be lower on the RAID-5 set due to the extra drive. Also following a disk failure and replacement, the rebuild time on the RAID-5 set will be higher than that on the RAID-1 set - but it shouldn't be that bad since we're only dealing with a 3 drive set.

A 3 drive RAID-5 set will provide twice as much storage as the RAID-1 set, but do you really need it for this kind of server workload?

Edit: Corrected the IOPS for a 10K drive from 130 to 140.

sprkymrk

astorrs wrote:

A 3 drive RAID-5 set will provide twice as much storage as the RAID-1 set, but do you really need it for this kind of server workload?

Likewise will a 33% increase be noticable on this kind of workload?

Also, can you provide a source for your calculations? Thanks.

dynamik

sprkymrk wrote:

Also, can you provide a source for your calculations? Thanks.

That's xkcd if you haven't seen it before

astorrs

sprkymrk wrote:

Likewise will a 33% increase be noticable on this kind of workload?

Also, can you provide a source for your calculations?

I guess that would all depend on how much spam they get.

I still don't see any benefit to RAID-5 given the sequential workload of an Edge Transport role Exchange server. I would guess the writes would account for about 50% (but an Exchange 2007 guru could clear that up - HeroPsycho/royal any comments?). And the overhead of doing software parity combined with the decreased MTBF, why bother unless you need the extra disk space.

As for the calculations are you questioning my math or the numbers used?

They are standard numbers used in the storage industry for calculating the number of spindles required given a workload and particular RAID set when designing SAN storage. I pulled them from some EMC docs I use (but you'll need an EMC Powerlink account with either Customer or Partner level access to get to the PDFs). SNIA probably has some free tutorials that cover the same stuff (remember I wasn't accounting for things like controller cache since this was all software based).

sprkymrk

astorrs wrote:

As for the calculations are you questioning my math or the numbers used?

I wasn't questioning either, I just like to have information like that for future reference.

Just as an FYI - Here are the MS recommended setups for Exchange (keeping in mind that a server hosting mailboxes will have different recommendations than one as a Bridgehead only, etc.) and also only hardware RAID is discussed:

http://technet.microsoft.com/en-us/library/bb124129(EXCHG.65).aspx


And one other interesting article on the subject:

http://www.tech-faq.com/exchange-server-2003-data-storage-and-management.shtml

astorrs

sprkymrk wrote:

I just like to have information like that for future reference.

Check your PMs, I'll send you some - I just can't link directly to it on PowerLink (since you'll be asked to login). None of it is confidential.

HeroPsycho

For Exchange server performance, RAID5 is actually never the preferred solution, although it is deemed acceptable for Mailbox stores that don't need high performance.

For HT servers that are simply rapidly reading and writing as they send mail off or queue them up, RAID5 would be a poorer choice. You don't need 3 disks. If anything, you need 4 disks to separate the queue disks from the OS and page files if under high demand.

Rikku

Check your PMs, I'll send you some - I just can't link directly to it on PowerLink (since you'll be asked to login). None of it is confidential.

Astorrs, I am interested in the same info. Please PM me as well if that is ok with you.

-Rikku