SSD Array?

[GuyJD]

I'm speccing up our new server and I'm toying with the idea of running the OS off a SSD raid 5 Array, is there any advantage or should I just go with a 2 disk mirror?

 

The server will be the primary domain controller also running DHCP and DNS.

[3s-gtech]

Don't run RAID 5. Write performance is often terrible, even with SSDs. RAID 10 is your friend.

[GuyJD]

that makes sense but is it worth going Raid 10 over Raid 1? is it really going to make that much difference to the speed?

[MalekoUK]

that makes sense but is it worth going Raid 10 over Raid 1? is it really going to make that much difference to the speed?

 

Fault Tolerance...

 

The server will be the primary domain controller also running DHCP and DNS.

 

Fault Tolerance...

[zag]

NO NO NO!

 

Why complicate a system for the sake of it? Just buy Intel SSD's and they never really fail(always have a backup just in case). Speed is not an issue. Speed of recovery of data is so much quicker.

 

EDIT1: Saying that I do use RAID5 on my home NAS that has 4 x 1tb SSD's in and it works OK.

 

EDIT2: Our Domain controller runs on a single SSD and has done for the last 3 years. No issues at all. We do have a backup domain controller as well.

Edited September 29, 2015 by zag

[MalekoUK]

NO NO NO!

 

Why complicate a system for the sake of it? Just buy Intel SSD's and they never really fail(always have a backup just in case). Speed is not an issue. Speed of recovery of data is so much quicker.

 

EDIT1: Saying that I do use RAID5 on my home NAS that has 4 x 1tb SSD's in and it works OK.

 

EDIT2: Our Domain controller runs on a single SSD and has done for the last 3 years. No issues at all. We do have a backup domain controller as well.

 

 

No matter how reliable SSD's are, I still never trust them entirely

 

Personally I would go R5 with SSDs.

[win]

For a DC which hardly takes up any space or resources, i'd also go with a mirror.

 

raid 5 and 10 are used when you need larger storage.

[localzuk]

Sorry @zag, but that is just terrible advice. For the OS drive, it should be at a minimum RAID1 - so that if one fails, the server can keep running. If you only run it off a single disk, you are very much putting your eggs in one basket. Regardless of anecdotal evidence of SSDs not failing, they can and do fail. Remember, everyone's environment is different, so whilst your own might be pretty stable, others might not be.

 

There's no need for RAID 10 or RAID 5 for OS disks, and for data disks I'd now say run them as JBOD with Windows Storage Spaces rather than RAID anyway.

[PotNoodleTech]

2 x SSD in raid 1 is all you need. If you really want to leverage reliability - include a third drive as a hot spare.

 

That being said, SSD RAID5 is fine, as long as you have a battery backup'd cache on you're raid card you should get stellar performance.

 

Here's a 7 disk Array I made earlier, made of £60 SSD's and an entry level dell Raid card. It's the kind of performance we could only dream of 5 years ago.

 

[sonofsanta]

For a DC/DNS/DHCP (DCNSHCP?) you don't need any more space than you'd get from a 120GB SSD in a RAID 1 mirror. RAID10 is no more fault tolerant than RAID1 - less, if anything, as you've got more disks and thus more chance of something going wrong.

 

An extra SSD that small is not going to add a great deal to the cost of the server, so it's absolutely worth it considering the benefit.

[zag]

A couple of points that are worth thinking about:

 

- Every extra drive you add to a setup makes it 100% more likely a disk will fail

- RAID can be the cause of issues on its own.

 

I still maintain that RAID is a legacy technology invented for mechanical based hard disks.

[localzuk]

A couple of points that are worth thinking about:

 

- Every extra drive you add to a setup makes it 100% more likely a disk will fail

 

But reduces the chance the server will go offline also...

 

- RAID can be the cause of issues on its own.

 

I don't think I've ever experienced RAID itself causing total downtime of a server. I have experienced downtime of a server due to a dead disk though. I suspect this would be the case in pretty much all schools that I know of.

 

I still maintain that RAID is a legacy technology invented for mechanical based hard disks.

 

I hate to say it but you seem to be missing the point of RAID. It is there for continuity of service. 2 disks means you have a greater chance of your server carrying on working.