vdev question - build followup

[Geoffrey O'Brien]

My First thread about the build:
https://forums.freenas.org/index.php?threads/supermicro-x10sl7-f-o.28431/#post-185716

I have a question about drives.

The drives I have on hand are:
8x4tb HGST 7200rpm
2x4tb WD Red 5400rpm
6x256gb samsung ssd

Should I put all 10 drives in as a single vdev, possibly using the WD's as spares or just throw them all in as one big vdev? Will I see a performance hit with the mixed speeds?

I was also thinking about using the ssd's in a raidz2 and using them for my jails.

Thanks for the advise.

 

[Robert Trevellyan]

The drives I have on hand are:
8x4tb HGST 7200rpm
2x4tb WD Red 5400rpm
6x256gb samsung ssd

Should I put all 10 drives in as a single vdev, possibly using the WD's as spares or just throw them all in as one big vdev? Will I see a performance hit with the mixed speeds?

You should expect pool performance to be limited by the slowest drives. That doesn't necessarily mean a pool containing only the 7200RPM will be measurably faster, as your bottleneck may lie elsewhere, e.g. the network.

I was also thinking about using the ssd's in a raidz2 and using them for my jails.

Seems like a waste to me, but I guess if you have no better use for them, why not?

 

[SweetAndLow]

You could do a 10 disk raidz2 with those drives and you get the performance of the slowest drive. But for certain use cases you wouldn't notice a lack of performance. You don't need the ssd and they probably wouldn't help you but without knowing what you are using this for makes it hard to know what performer you need.

 

[jgreco]

If you have lots of people accessing small files on a constant basis, the 5400 drives will definitely feel a bit slower. For a few users accessing an occasional file (whether large or small), the difference between 5400 and 7200 would usually not be noticeable.

In general the difference would mostly be noticed on a busy pool. This is because if the pool isn't busy, and you request file /foo/bar/x/y/z, the drives aren't busy and they've got to do a few seeks to locate the data, but you, as a slow human snail-paced being, are not going to be able to see the difference between 40ms to get your file and 50ms to get your file. But if the pool is very busy, then the extra speed may be reducing the amount of busywait for those seeks to happen.

 

[Geoffrey O'Brien]

This will be my media server, mostly plex, and possibly 2-3 transcodes at a time. I was thinking separating the jails from the data may give me a bit more performance?

 

[jgreco]

Maybe, but probably not worth a lot of effort to do so.