<div dir="ltr"><div><div><div><div><div><div><div><div>Thomas is asking the right questions.<br><br></div>Especially, the system specs.<br></div>You'll need at least a 1Gb RAM for each 1Tb of disk.<br></div>If you are running a lean system that doesn't have enough RAM, then ZFS won't be able to pre-fetch data.<br>
</div>Caching is pretty important on systems with a large amount of data.<br><br></div>If you are using dedup, you'll need at least 5Gb of RAM for each 1Tb of disk.<br></div>I would assume that you have enough RAM because you can still mount your pool(s).<br>
</div><div>From the lag issues that you've described it kind of sounds like it could be a RAM issue.<br><br></div><div>ZFS like ECC RAM, but that's really only important for checksumming and parity computations.<br>
</div><div>ZFS uses RAM in all sorts of interesting ways, but it sounds like you might not have enough RAM for your read-cache to be working correctly(or at all).<br></div><div>How are your write speeds?<br></div><div>I you are having write speed issues as well as reads, then I would say that points to RAM issues as well.<br>
All the writes that come into the zpools get queue up to the write-cache before the are added to the Intent Log and flushed to disk.<br><br></div>I'm not sure about any alignment issue, but like Thomas alluded to if your pool is nearing capacity you could see some performance degradation as well.<br>
<br></div><div>I have a buddy that uses 3ware 6gbps RAID controllers, but he's running BSD.<br></div><div>I'm not certain that would matter, but ZFS and BSD tend to play nice.<br><br></div><div>Can you give us your system specs?<br>
</div><div><br></div>-> Jake<br><div><br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Sat, Feb 8, 2014 at 1:09 PM, T L <span dir="ltr"><<a href="mailto:tlunde@gmail.com" target="_blank">tlunde@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><p dir="ltr">Re: performance issues? </p>
<p dir="ltr">How full is the pool?<br>
How much RAM does the system have?<br>
Are the ZFS options for de-duplication or compression turned on?<br>
Are you using a L2ARC cache?<br>
If you have any 4k drives, are the filesystem partitions aligned optimally (ashift=12 maybe)?</p>
<p dir="ltr">Thomas<br>
</p><div class="HOEnZb"><div class="h5">
<div class="gmail_quote">On Feb 8, 2014 11:09 AM, <<a href="mailto:tclug@freakzilla.com" target="_blank">tclug@freakzilla.com</a>> wrote:<br type="attribution"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Hello people,<br>
<br>
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?<br>
<br>
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.<br>
<br>
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.<br>
<br>
So, a couple questions:<br>
<br>
1. Can anyone think of any other reason the filesystem is suddenly acting<br>
like this? It was fine when there was less data on it.<br>
<br>
2. I feel it should be seemless to move the ZFS pool/drive array from one<br>
SATA connection to another. I this correct? The array uses two separate<br>
SATA connections, but I figure worst case I plug them in in the wrong<br>
order, it fails, I reverse them and restart and no problem. Is this<br>
true? I don't want to nuke my ZFS pool...<br>
<br>
3. Can anyone recommend a good SATA card with e-SATA ports? I have one<br>
that came with the drive enclosure but it is not Linux compatible.<br>
<br>
<br>
Thanks!<br>
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</blockquote></div>
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