SAS HDD question

[IAmATeaf]

My server at the mo has 8 300Gb 10K SAS drives configured in RAID10.

I've been offered the chance to do a straight swap of these drives for 8 500Gb 7k SAS drives.

Probably a stupid question and I wouldn't mind the extra space but would going from 10k drives to 7k drives impact performance that much that I'd even notice.

I use my server to run a test rig which consists of a DC, fileshare server, SQL server, SCCM server and an Exchange server. I do have a number of other VMs that I do power up from time to time.

Single user, me with no real end users connected.

 

[PistolPete]

Personally I'd doubt you'd notice.

 

[Jimbo.UK]

In your case.. In RAID 10 it's still going to be fast, unless you moving large volumes of data as a hobby or love to benchmark large numbers... you won't really notice it. +-~20% average ignoring peak/trough.

Go 7K when capacity is your number one goal and performance is a nice secondary. 10k/15k is the opposite

 

[Little_Crow]

Are they definitely SAS rather than SATA?
They'll just plug in and work regardless, but there are differences in error correction that make SAS a slightly better choice.

As a really rough guide 7.2K drives give ~75-100 iops, whereas 10K drives give 125-150 iops. So at the very worst you could lose half your performance, but in RAID10 you're getting a nice performance boost any way so you may not even notice.

Best of both worlds - get yourself an external SAS enclosure and card and use them all.

 

[IAmATeaf]

I think you're correct, I got some perf tests done

300Gb 10K drives

500Gb 7.2K drives

 

[IAmATeaf]

Ended up getting the best of both worlds, seems for some reason the server was being decommissioned and scrapped, God knows why as from what I know it was a decent bit of kit, would have had the complete server but they wouldn't/couldn't do that. So I ended up getting a disk cage with 8 disks in addition rather then as a swap, the remaining 12 disks in the machine as well the machine were scrapped.

Also chanced my luck and asked for the SAS RAID card and battery backup unit which all arrived last week.

Had to mod my server slightly, had to get the drill, pliers and soldering iron out and ransack my house for suitable cables as the power connectors were different in that my disk cage is powered only using 12v lines but the disk cage that arrived seemed to also need a 5v line but the disks are now mounted as is the SAS card and BBU and everything is working and as an added bonus nothing has blown up. yet.

 

[Xez]

Are they definitely SAS rather than SATA?
They'll just plug in and work regardless, but there are differences in error correction that make SAS a slightly better choice.

As a really rough guide 7.2K drives give ~75-100 iops, whereas 10K drives give 125-150 iops. So at the very worst you could lose half your performance, but in RAID10 you're getting a nice performance boost any way so you may not even notice.

Best of both worlds - get yourself an external SAS enclosure and card and use them all.

I was going to say this, they're probably in-line SAS rather than proper enterprise SAS drives. Personally I'd keep the 300GB 10k drives.

 

[IAmATeaf]

I was going to say this, they're probably in-line SAS rather than proper enterprise SAS drives. Personally I'd keep the 300GB 10k drives.

I've ended up with both so still have the 8 300Gb drives plus the 8 500Gb drives.

How can I tell if they are near-line or real SAS drives?

EDIT: Can't believe I never noticed before, the 300Gb drives have SAS written on them and the 500Gb drives have SATA written on them. The model numbers are ST9300605SS and ST9500620NS, respectively, so both enterprise class drives. In July apparently the data centre is going to be ejecting more servers so might see what else is available but the problem is the centre is up north so I only get snippets of information but free is free so beggars can't be choosers I suppose.