Re: performance issues?

How full is the pool?
How much RAM does the system have?
Are the ZFS options for de-duplication or compression turned on?
Are you using a L2ARC cache?
If you have any 4k drives, are the filesystem partitions aligned optimally
(ashift=12 maybe)?

Thomas
 On Feb 8, 2014 11:09 AM, <tclug at freakzilla.com> wrote:

> Hello people,
>
> Alright, my RAID/ZFS drama continues. The thing was working perfectly for
> a few months, and now performance has turned abysmal. It's a 16TB array
> running as a media server. If there's one client streaming data, no
> problem. Even two. But add a bunch of little things accessing the pool and
> it crawls. You hit Play on a video and there's a 5 second delay before
> starting. Skip a music track, again, 5 second delay. Kinda risiculous,
> right?
>
> No errors anywhere, zpool srub found nothing wrong, etc. The server's load
> average, though, is always super high (like >4, sometimes up to 6), a lot
> of waiting for IO.
>
> The only idea I have is that using the system's built-in SATA to run eight
> 3tb harddrives is not able to keep up with demands. So I'm thinking of
> getting a nice SATA expeansion card to off-load some of the processing off
> the CPU, hopefully that'll help.
>
> So, a couple questions:
>
> 1. Can anyone think of any other reason the filesystem is suddenly acting
>    like this? It was fine when there was less data on it.
>
> 2. I feel it should be seemless to move the ZFS pool/drive array from one
>    SATA connection to another. I this correct? The array uses two separate
>    SATA connections, but I figure worst case I plug them in in the wrong
>    order, it fails, I reverse them and restart and no problem. Is this
>    true? I don't want to nuke my ZFS pool...
>
> 3. Can anyone recommend a good SATA card with e-SATA ports? I have one
>    that came with the drive enclosure but it is not Linux compatible.
>
>
> Thanks!
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