`<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">correction below...<div><br><div><div>On Jul 30, 2014, at 10:37 PM, Richard Elling <<a href="mailto:richard.elling@richardelling.com">richard.elling@richardelling.com</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><meta http-equiv="Content-Type" content="text/html charset=windows-1252"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">apologies for the long post, data for big systems tends to do that, comments below...<div><br><div><div>On Jul 30, 2014, at 9:10 PM, wuffers <<a href="mailto:moo@wuffers.net">moo@wuffers.net</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div dir="ltr">So as I suspected, I lost 2 weeks of scrub time after the resilver. I started a scrub again, and it's going extremely slow (~13x slower than before):<div><br></div><div><div> pool: tank</div><div> state: ONLINE</div>
<div> scan: scrub in progress since Tue Jul 29 15:41:27 2014</div><div> 45.4G scanned out of 24.5T at 413K/s, (scan is slow, no estimated time)</div><div> 0 repaired, 0.18% done</div></div><div><br></div><div># iostat -zxCn 60 2 (2nd batch output)</div>
<div><br></div><div><div> extended device statistics</div><div> r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b device</div><div> 143.7 1321.5 5149.0 46223.4 0.0 1.5 0.0 1.0 0 120 c1</div>
<div> 2.4 33.3 72.0 897.5 0.0 0.0 0.0 0.6 0 2 c1t5000C50055F8723Bd0</div><div> 2.7 22.8 82.9 1005.4 0.0 0.0 0.0 0.9 0 2 c1t5000C50055E66B63d0</div><div> 2.2 24.4 73.1 917.7 0.0 0.0 0.0 0.7 0 2 c1t5000C50055F87E73d0</div>
<div> 3.1 26.2 120.9 899.8 0.0 0.0 0.0 0.8 0 2 c1t5000C50055F8BFA3d0</div><div> 2.8 16.5 105.9 941.6 0.0 0.0 0.0 1.0 0 2 c1t5000C50055F9E123d0</div><div> 2.5 25.6 86.6 897.9 0.0 0.0 0.0 0.7 0 2 c1t5000C50055F9F0B3d0</div>
<div> 2.3 19.9 85.3 967.8 0.0 0.0 0.0 1.2 0 2 c1t5000C50055F9D3B3d0</div><div> 3.1 38.3 120.7 1053.1 0.0 0.0 0.0 0.8 0 3 c1t5000C50055E4FDE7d0</div><div> 2.6 12.7 81.8 854.3 0.0 0.0 0.0 1.6 0 2 c1t5000C50055F9A607d0</div>
<div> 3.2 25.0 121.7 871.7 0.0 0.0 0.0 0.8 0 2 c1t5000C50055F8CDA7d0</div><div> 2.5 30.6 93.0 941.2 0.0 0.0 0.0 0.9 0 2 c1t5000C50055E65877d0</div><div> 3.1 43.7 101.4 1004.2 0.0 0.0 0.0 1.0 0 4 c1t5000C50055F9E7D7d0</div>
<div> 2.3 24.0 92.2 965.8 0.0 0.0 0.0 0.9 0 2 c1t5000C50055FA0AF7d0</div><div> 2.5 25.3 99.2 872.9 0.0 0.0 0.0 0.8 0 2 c1t5000C50055F9FE87d0</div><div> 2.9 19.0 116.1 894.8 0.0 0.0 0.0 1.2 0 2 c1t5000C50055F9F91Bd0</div>
<div> 2.6 38.9 96.1 915.4 0.0 0.1 0.0 1.2 0 4 c1t5000C50055F9FEABd0</div><div> 3.2 45.6 135.7 973.5 0.0 0.1 0.0 1.5 0 5 c1t5000C50055F9F63Bd0</div><div> 3.1 21.2 105.9 966.6 0.0 0.0 0.0 1.0 0 2 c1t5000C50055F9F3EBd0</div>
<div> 2.8 26.7 122.0 781.6 0.0 0.0 0.0 0.7 0 2 c1t5000C50055F9F80Bd0</div><div> 3.1 31.6 119.9 932.5 0.0 0.0 0.0 1.1 0 3 c1t5000C50055F9FB8Bd0</div><div> 3.1 32.5 123.3 924.1 0.0 0.0 0.0 0.9 0 3 c1t5000C50055F9F92Bd0</div>
<div> 2.9 17.0 113.8 952.0 0.0 0.0 0.0 1.2 0 2 c1t5000C50055F8905Fd0</div><div> 3.0 23.4 111.0 871.1 0.0 0.0 0.0 1.5 0 2 c1t5000C50055F8D48Fd0</div><div> 2.8 21.4 105.5 858.0 0.0 0.0 0.0 1.0 0 2 c1t5000C50055F9F89Fd0</div>
<div> 3.5 16.4 87.1 941.3 0.0 0.0 0.0 1.4 0 2 c1t5000C50055F9EF2Fd0</div><div> 2.1 33.8 64.5 897.5 0.0 0.0 0.0 0.5 0 2 c1t5000C50055F8C3ABd0</div><div> 3.0 21.8 72.3 1005.4 0.0 0.0 0.0 1.0 0 2 c1t5000C50055E66053d0</div>
<div> 3.0 37.8 106.9 1053.5 0.0 0.0 0.0 0.9 0 3 c1t5000C50055E66503d0</div><div> 2.7 26.0 107.7 897.9 0.0 0.0 0.0 0.7 0 2 c1t5000C50055F9D3E3d0</div><div> 2.2 38.9 96.4 918.7 0.0 0.0 0.0 0.9 0 4 c1t5000C50055F84FB7d0</div>
<div> 2.8 21.4 111.1 953.6 0.0 0.0 0.0 0.7 0 1 c1t5000C50055F8E017d0</div><div> 3.0 30.6 104.3 940.9 0.0 0.1 0.0 1.5 0 3 c1t5000C50055E579F7d0</div><div> 2.8 26.4 90.9 901.1 0.0 0.0 0.0 0.9 0 2 c1t5000C50055E65807d0</div>
<div> 2.4 24.0 96.7 965.8 0.0 0.0 0.0 0.9 0 2 c1t5000C50055F84A97d0</div><div> 2.9 19.8 109.4 967.8 0.0 0.0 0.0 1.1 0 2 c1t5000C50055F87D97d0</div><div> 3.8 16.1 106.4 943.1 0.0 0.0 0.0 1.3 0 2 c1t5000C50055F9F637d0</div>
<div> 2.2 17.1 72.7 966.6 0.0 0.0 0.0 1.4 0 2 c1t5000C50055E65ABBd0</div><div> 2.7 12.7 86.0 863.3 0.0 0.0 0.0 1.5 0 2 c1t5000C50055F8BF9Bd0</div><div> 2.7 23.2 101.8 871.1 0.0 0.0 0.0 1.0 0 2 c1t5000C50055F8A22Bd0</div>
<div> 4.5 43.6 134.7 1004.2 0.0 0.0 0.0 1.0 0 4 c1t5000C50055F9379Bd0</div><div> 2.8 24.0 87.9 917.7 0.0 0.0 0.0 0.8 0 2 c1t5000C50055E57A5Fd0</div><div> 2.9 18.8 119.0 894.3 0.0 0.0 0.0 1.1 0 2 c1t5000C50055F8CCAFd0</div>
<div> 3.4 45.7 128.1 976.8 0.0 0.1 0.0 1.2 0 5 c1t5000C50055F8B80Fd0</div><div> 2.7 24.9 100.2 871.7 0.0 0.0 0.0 0.8 0 2 c1t5000C50055F9FA1Fd0</div><div> 4.8 26.8 128.6 781.6 0.0 0.0 0.0 0.7 0 2 c1t5000C50055E65F0Fd0</div>
<div> 2.7 16.3 109.5 941.6 0.0 0.0 0.0 1.1 0 2 c1t5000C50055F8BE3Fd0</div><div> 3.1 21.1 119.9 858.0 0.0 0.0 0.0 1.1 0 2 c1t5000C50055F8B21Fd0</div><div> 2.8 31.8 108.5 932.5 0.0 0.0 0.0 1.0 0 3 c1t5000C50055F8A46Fd0</div>
<div> 2.4 25.3 87.4 872.9 0.0 0.0 0.0 0.8 0 2 c1t5000C50055F856CFd0</div><div> 3.3 32.0 125.2 924.1 0.0 0.0 0.0 1.2 0 3 c1t5000C50055E6606Fd0</div><div> 289.9 169.0 3905.0 12754.1 0.0 0.2 0.0 0.4 0 10 c2</div>
<div> 146.6 14.1 1987.9 305.2 0.0 0.0 0.0 0.2 0 4 c2t500117310015D579d0</div><div> 143.4 10.6 1917.1 205.2 0.0 0.0 0.0 0.2 0 3 c2t50011731001631FDd0</div><div> 0.0 144.3 0.0 12243.7 0.0 0.1 0.0 0.9 0 3 c2t5000A72A3007811Dd0</div>
<div> 0.0 14.6 0.0 75.8 0.0 0.0 0.0 0.1 0 0 c4</div><div> 0.0 7.3 0.0 37.9 0.0 0.0 0.0 0.1 0 0 c4t0d0</div><div> 0.0 7.3 0.0 37.9 0.0 0.0 0.0 0.1 0 0 c4t1d0</div>
<div> 284.8 171.5 3792.8 12786.2 0.0 0.2 0.0 0.4 0 10 c12</div><div> 0.0 144.3 0.0 12243.7 0.0 0.1 0.0 0.9 0 3 c12t5000A72B300780FFd0</div><div> 152.3 13.3 2004.6 255.9 0.0 0.0 0.0 0.2 0 4 c12t500117310015D59Ed0</div>
<div> 132.5 13.9 1788.2 286.6 0.0 0.0 0.0 0.2 0 3 c12t500117310015D54Ed0</div><div> 0.0 13.5 0.0 75.8 0.0 0.0 0.8 0.1 0 0 rpool</div><div> 718.4 1653.5 12846.8 71761.5 34.0 2.0 14.3 0.8 7 51 tank</div>
</div><div><br></div><div><div class="gmail_extra">This doesn't seem any busier than my earlier output (6% wait, 68% busy, asvc_t 1.1ms) and the dev team confirms that their workload hasn't changed for the past few days. If my math is right.. this will take ~719 days to complete.</div></div></div></blockquote><div><br></div><div>The %busy for controllers is a sum of the %busy for all disks on the controller, so</div><div>is can be large, but overall isn't interesting. With HDDs, there is no way you can </div><div>saturate the controller, so we don't really care what the %busy shows.</div><div><br></div><div>The more important item is that the number of read ops is fairly low for all but 4 disks.</div><div>Since you didn't post the pool configuration, we can only guess that they might be a</div><div>souce of the bottleneck. </div></div></div></div></blockquote><div><br></div><div>the above paragraph missed the editor's cut. You did post the pool config, thanks!</div><div> -- richard</div><br><blockquote type="cite"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div><div><div><br></div><div>You're seeing a lot of reads from the cache devices. How much RAM does this system</div><div>have?</div><br><blockquote type="cite"><div dir="ltr">
<div class="gmail_extra"><br></div><div class="gmail_extra">Anything I can tune to help speed this up?<br></div></div></blockquote><div><br></div><div>methinks the scrub I/Os are getting starved and since they are low priority, they </div><div>could get very starved. In general, I wouldn't worry about it, but I understand </div><div>why you might be nervous. Keep in mind that in ZFS scrubs are intended to find </div><div>errors on idle data, not frequently accessed data.</div><div><br></div><div>more far below...</div><br><blockquote type="cite"><div dir="ltr"><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Jul 29, 2014 at 3:29 PM, wuffers <span dir="ltr"><<a href="mailto:moo@wuffers.net" target="_blank">moo@wuffers.net</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex; position: static; z-index: auto;"><div dir="ltr"><div>Going to try to answer both responses in one message..</div>
<div class=""><div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
Short answer, yes. … Keep in mind that<br><br>1. a scrub runs in the background (so as not to impact production I/O, this was not always the case and caused serious issues in the past with a pool being unresponsive due to a scrub)<br>
<br>2. a scrub essentially walks the zpool examining every transaction in order (as does a resilver)<br><br>So the time to complete a scrub depends on how many write transactions since the pool was created (which is generally related to the amount of data but not always). You are limited by the random I/O capability of the disks involved. With VMs I assume this is a file server, so the I/O size will also affect performance.</blockquote>
<div><br></div></div><div>I haven't noticed any slowdowns in our virtual environments, so I guess that's a good thing it's so low priority that it doesn't impact workloads. </div><div class=""><div><br></div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
Run the numbers… you are scanning 24.2TB at about 5.5MB/sec … 4,613,734 seconds or 54 days. And that assumes the same rate for all of the scan. The rate will change as other I/O competes for resources.<br></blockquote><div>
<br></div></div><div>The number was fluctuating when I started the scrub, and I had seen it go as high as 35MB/s at one point. I am certain that our Hyper-V workload has increased since the last scrub, so this does make sense.</div>
<div class="">
<div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">Looks like you have a fair bit of activity going on (almost 1MB/sec of writes per spindle).<br>
</blockquote><div><br></div></div><div>As Richard correctly states below, this is the aggregate since boot (uptime ~56 days). I have another output from iostat as per his instructions below. </div><div class=""><div> </div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
Since this is storage for VMs, I assume this is the storage server for separate compute servers? Have you tuned the block size for the file share you are using? That can make a huge difference in performance.<br></blockquote>
<div><br></div></div><div>Both the Hyper-V and VMware LUNs are created with 64K block sizes. From what I've read of other performance and tuning articles, that is the optimal block size (I did some limited testing when first configuring the SAN, but results were somewhat inconclusive). Hyper-V hosts our testing environment (we integrate with TFS, a MS product, so we have no choice here) and probably make up the bulk of the workload (~300+ test VMs with various OSes). VMware hosts our production servers (Exchange, file servers, SQL, AD, etc - ~50+ VMs).</div>
<div class="">
<div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">I also noted that you only have a single LOG device. Best Practice is to mirror log devices so you do not lose any data in flight if hit by a power outage (of course, if this server has more UPS runtime that all the clients that may not matter).<br>
</blockquote><div><br></div></div><div>Actually, I do have a mirror ZIL device, it's just disabled at this time (my ZIL devices are ZeusRAMs). At some point, I was troubleshooting some kernel panics (turned out to be a faulty SSD on the rpool), and hadn't re-enabled it yet. Thanks for the reminder (and yes, we do have a UPS as well). </div>
<div><br></div><div>And oops.. re-attaching the ZIL as a mirror triggered a resilver now, suspending or canceling the scrub? Will monitor this and restart the scrub if it doesn't by itself.</div><div><br></div><div><div>
pool: tank</div><div> state: ONLINE</div><div>status: One or more devices is currently being resilvered. The pool will</div><div> continue to function, possibly in a degraded state.</div><div>action: Wait for the resilver to complete.</div>
<div> scan: resilver in progress since Tue Jul 29 14:48:48 2014</div><div> 3.89T scanned out of 24.5T at 3.06G/s, 1h55m to go</div><div> 0 resilvered, 15.84% done</div></div><div><br></div><div>At least it's going very fast. EDIT: Now about 67% done as I finish writing this, speed dropping to ~1.3G/s. </div>
<div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<div style="word-wrap:break-word"><div>maybe, maybe not<br></div><div class=""><div><br></div><div>this is slower than most, surely slower than desired</div></div></div></blockquote></div></blockquote>
<div><br></div><div>Unfortunately reattaching the mirror to my log device triggered a resilver. Not sure if this is desired behavior, but yes, 5.5MB/s seems quite slow. Hopefully after the resilver the scrub will progress where it left off. </div>
<div class="">
<div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<div style="word-wrap:break-word"><div>The estimate is often very wrong, especially for busy systems.</div><div>If this is an older ZFS implementation, this pool is likely getting pounded by the</div><div>ZFS write throttle. There are some tunings that can be applied, but the old write</div>
<div>throttle is not a stable control system, so it will always be a little bit unpredictable.</div></div></blockquote></div></blockquote><div><br></div></div><div>The system is on r151008 (my BE states that I upgraded back in February, putting me in r151008j or so), with all the pools upgraded for the new enhancements as well as activating the new L2ARC compression feature. Reading the release notes, the ZFS write throttle enhancements were in since r151008e so I should be good there.</div>
<div class="">
<div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<div style="word-wrap:break-word"><div><blockquote type="cite"><div dir="ltr"># iostat -xnze</div></blockquote><div><br></div></div><div>Unfortunately, this is the performance since boot and is not suitable for performance</div>
<div>analysis unless the system has been rebooted in the past 10 minutes or so. You'll need</div><div>to post the second batch from "iostat -zxCn 60 2"</div></div></blockquote></div></blockquote><div>
<br>
</div></div><div>Ah yes, that was my mistake. Output from second count (before re-attaching log mirror):</div><div class=""><div><br></div><div># iostat -zxCn 60 2</div><div><br></div><div> extended device statistics</div>
</div><div> r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b device</div><div> 255.7 1077.7 6294.0 41335.1 0.0 1.9 0.0 1.4 0 153 c1</div><div> 5.3 23.9 118.5 811.9 0.0 0.0 0.0 1.1 0 3 c1t5000C50055F8723Bd0</div>
<div> 5.9 14.5 110.0 834.3 0.0 0.0 0.0 1.3 0 2 c1t5000C50055E66B63d0</div><div> 5.6 16.6 123.8 822.7 0.0 0.0 0.0 1.3 0 2 c1t5000C50055F87E73d0</div><div> 4.7 27.8 118.6 796.6 0.0 0.0 0.0 1.3 0 3 c1t5000C50055F8BFA3d0</div>
<div> 5.6 14.5 139.7 833.8 0.0 0.0 0.0 1.6 0 3 c1t5000C50055F9E123d0</div><div> 4.4 27.1 112.3 825.2 0.0 0.0 0.0 0.8 0 2 c1t5000C50055F9F0B3d0</div><div> 5.0 20.2 121.7 803.4 0.0 0.0 0.0 1.2 0 3 c1t5000C50055F9D3B3d0</div>
<div> 5.4 26.4 137.0 857.3 0.0 0.0 0.0 1.4 0 4 c1t5000C50055E4FDE7d0</div><div> 4.7 12.3 123.7 832.7 0.0 0.0 0.0 2.0 0 3 c1t5000C50055F9A607d0</div><div> 5.0 23.9 125.9 830.9 0.0 0.0 0.0 1.3 0 3 c1t5000C50055F8CDA7d0</div>
<div> 4.5 31.4 112.2 814.6 0.0 0.0 0.0 1.1 0 3 c1t5000C50055E65877d0</div><div> 5.2 24.4 130.6 872.5 0.0 0.0 0.0 1.2 0 3 c1t5000C50055F9E7D7d0</div><div> 4.1 21.8 103.7 797.2 0.0 0.0 0.0 1.1 0 3 c1t5000C50055FA0AF7d0</div>
<div> 5.5 24.8 129.8 802.8 0.0 0.0 0.0 1.5 0 4 c1t5000C50055F9FE87d0</div><div> 5.7 17.7 137.2 797.6 0.0 0.0 0.0 1.4 0 3 c1t5000C50055F9F91Bd0</div><div> 6.0 30.6 139.1 852.0 0.0 0.1 0.0 1.5 0 4 c1t5000C50055F9FEABd0</div>
<div> 6.1 34.1 137.8 929.2 0.0 0.1 0.0 1.9 0 6 c1t5000C50055F9F63Bd0</div><div> 4.1 15.9 101.8 791.4 0.0 0.0 0.0 1.6 0 3 c1t5000C50055F9F3EBd0</div><div> 6.4 23.2 155.2 878.6 0.0 0.0 0.0 1.1 0 3 c1t5000C50055F9F80Bd0</div>
<div> 4.5 23.5 106.2 825.4 0.0 0.0 0.0 1.1 0 3 c1t5000C50055F9FB8Bd0</div><div> 4.0 23.2 101.1 788.9 0.0 0.0 0.0 1.3 0 3 c1t5000C50055F9F92Bd0</div><div> 4.4 11.3 125.7 782.3 0.0 0.0 0.0 1.9 0 3 c1t5000C50055F8905Fd0</div>
<div> 4.6 20.4 129.2 823.0 0.0 0.0 0.0 1.5 0 3 c1t5000C50055F8D48Fd0</div><div> 5.1 19.7 142.9 887.2 0.0 0.0 0.0 1.7 0 3 c1t5000C50055F9F89Fd0</div><div> 5.6 11.4 129.1 776.0 0.0 0.0 0.0 1.9 0 3 c1t5000C50055F9EF2Fd0</div>
<div> 5.6 23.7 137.4 811.9 0.0 0.0 0.0 1.2 0 3 c1t5000C50055F8C3ABd0</div><div> 6.8 13.9 132.4 834.3 0.0 0.0 0.0 1.8 0 3 c1t5000C50055E66053d0</div><div> 5.2 26.7 126.9 857.3 0.0 0.0 0.0 1.2 0 3 c1t5000C50055E66503d0</div>
<div> 4.2 27.1 104.6 825.2 0.0 0.0 0.0 1.0 0 3 c1t5000C50055F9D3E3d0</div><div> 5.2 30.7 140.9 852.0 0.0 0.1 0.0 1.5 0 4 c1t5000C50055F84FB7d0</div><div> 5.4 16.1 124.3 791.4 0.0 0.0 0.0 1.7 0 3 c1t5000C50055F8E017d0</div>
<div> 3.8 31.4 89.7 814.6 0.0 0.0 0.0 1.1 0 4 c1t5000C50055E579F7d0</div><div> 4.6 27.5 116.0 796.6 0.0 0.1 0.0 1.6 0 4 c1t5000C50055E65807d0</div><div> 4.0 21.5 99.7 797.2 0.0 0.0 0.0 1.1 0 3 c1t5000C50055F84A97d0</div>
<div> 4.7 20.2 116.3 803.4 0.0 0.0 0.0 1.4 0 3 c1t5000C50055F87D97d0</div><div> 5.0 11.5 121.5 776.0 0.0 0.0 0.0 2.0 0 3 c1t5000C50055F9F637d0</div><div> 4.9 11.3 112.4 782.3 0.0 0.0 0.0 2.3 0 3 c1t5000C50055E65ABBd0</div>
<div> 5.3 11.8 142.5 832.7 0.0 0.0 0.0 2.4 0 3 c1t5000C50055F8BF9Bd0</div><div> 5.0 20.3 121.4 823.0 0.0 0.0 0.0 1.7 0 3 c1t5000C50055F8A22Bd0</div><div> 6.6 24.3 170.3 872.5 0.0 0.0 0.0 1.3 0 3 c1t5000C50055F9379Bd0</div>
<div> 5.8 16.3 121.7 822.7 0.0 0.0 0.0 1.3 0 2 c1t5000C50055E57A5Fd0</div><div> 5.3 17.7 146.5 797.6 0.0 0.0 0.0 1.4 0 3 c1t5000C50055F8CCAFd0</div><div> 5.7 34.1 141.5 929.2 0.0 0.1 0.0 1.7 0 5 c1t5000C50055F8B80Fd0</div>
<div> 5.5 23.8 125.7 830.9 0.0 0.0 0.0 1.2 0 3 c1t5000C50055F9FA1Fd0</div><div> 5.0 23.2 127.9 878.6 0.0 0.0 0.0 1.1 0 3 c1t5000C50055E65F0Fd0</div><div> 5.2 14.0 163.7 833.8 0.0 0.0 0.0 2.0 0 3 c1t5000C50055F8BE3Fd0</div>
<div> 4.6 18.9 122.8 887.2 0.0 0.0 0.0 1.6 0 3 c1t5000C50055F8B21Fd0</div><div> 5.5 23.6 137.4 825.4 0.0 0.0 0.0 1.5 0 3 c1t5000C50055F8A46Fd0</div><div> 4.9 24.6 116.7 802.8 0.0 0.0 0.0 1.4 0 4 c1t5000C50055F856CFd0</div>
<div> 4.9 23.4 120.8 788.9 0.0 0.0 0.0 1.4 0 3 c1t5000C50055E6606Fd0</div><div> 234.9 170.1 4079.9 11127.8 0.0 0.2 0.0 0.5 0 9 c2</div><div> 119.0 28.9 2083.8 670.8 0.0 0.0 0.0 0.3 0 3 c2t500117310015D579d0</div>
<div> 115.9 27.4 1996.1 634.2 0.0 0.0 0.0 0.3 0 3 c2t50011731001631FDd0</div><div> 0.0 113.8 0.0 9822.8 0.0 0.1 0.0 1.0 0 2 c2t5000A72A3007811Dd0</div><div> 0.1 18.5 0.0 64.8 0.0 0.0 0.0 0.0 0 0 c4</div>
<div> 0.1 9.2 0.0 32.4 0.0 0.0 0.0 0.0 0 0 c4t0d0</div><div> 0.0 9.2 0.0 32.4 0.0 0.0 0.0 0.0 0 0 c4t1d0</div><div> 229.8 58.1 3987.4 1308.0 0.0 0.1 0.0 0.3 0 6 c12</div>
<div> 114.2 27.7 1994.8 626.0 0.0 0.0 0.0 0.3 0 3 c12t500117310015D59Ed0</div><div> 115.5 30.4 1992.6 682.0 0.0 0.0 0.0 0.3 0 3 c12t500117310015D54Ed0</div><div> 0.1 17.1 0.0 64.8 0.0 0.0 0.6 0.1 0 0 rpool</div>
<div> 720.3 1298.4 14361.2 53770.8 18.7 2.3 9.3 1.1 6 68 tank</div></div></blockquote></div></div></div></blockquote><div><br></div><div>ok, so the pool is issuing 720 read iops, including resilver workload, vs 1298 write iops.</div><div>There is plenty of I/O capacity left on the table here, as you can see by the %busy being</div><div>so low.</div><div><br></div><div>So I think the pool is not scheduling scrub I/Os very well. You can increase the number of</div><div>scrub I/Os in the scheduler by adjusting the zfs_vdev_scrub_max_active tunable. The</div><div>default is 2, but you'll have to consider that a share (in the stock market sense) where</div><div>the active sync reads and writes are getting 10 each. You can try bumping up the value</div><div>and see what happens over some time, perhaps 10 minutes or so -- too short of a time</div><div>and you won't get a good feeling for the impact (try this in off-peak time).</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>echo zfs_vdev_scrub_max_active/W0t5 | mdb -kw</div><div>will change the value from 2 to 5, increasing its share of the total I/O workload.</div><div><br></div><div>You can see the progress of scan (scrubs do scan) workload by looking at the ZFS</div><div>debug messages.</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>echo ::zfs_dbgmsg | mdb -k</div><div>These will look mysterious... they are. But the interesting bits are about how many blocks</div><div>are visited in some amount of time (txg sync interval). Ideally, this will change as you </div><div>adjust zfs_vdev_scrub_max_active.</div><div> -- richard</div><br><blockquote type="cite"><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex; position: static; z-index: auto;"><div dir="ltr"><div> </div><div>Is 153% busy correct on c1? Seems to me that disks are quite "busy", but are handling the workload just fine (wait at 6% and asvc_t at 1.1ms)</div>
<div><br></div><div>Interestingly, this is the same output now that the resilver is running:</div><div><br></div><div><div> extended device statistics</div><div> r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b device</div>
<div> 2876.9 1041.1 25400.7 38189.1 0.0 37.9 0.0 9.7 0 2011 c1</div><div> 60.8 26.1 540.1 845.2 0.0 0.7 0.0 8.3 0 39 c1t5000C50055F8723Bd0</div><div> 58.4 14.2 511.6 740.7 0.0 0.7 0.0 10.1 0 39 c1t5000C50055E66B63d0</div>
<div> 60.2 16.3 529.3 756.1 0.0 0.8 0.0 10.1 0 41 c1t5000C50055F87E73d0</div><div> 57.5 24.9 527.6 841.7 0.0 0.7 0.0 9.0 0 40 c1t5000C50055F8BFA3d0</div><div> 57.9 14.5 543.5 765.1 0.0 0.7 0.0 9.8 0 38 c1t5000C50055F9E123d0</div>
<div> 57.9 23.9 516.6 806.9 0.0 0.8 0.0 9.3 0 40 c1t5000C50055F9F0B3d0</div><div> 59.8 24.6 554.1 857.5 0.0 0.8 0.0 9.6 0 42 c1t5000C50055F9D3B3d0</div><div> 56.5 21.0 480.4 715.7 0.0 0.7 0.0 8.9 0 37 c1t5000C50055E4FDE7d0</div>
<div> 54.8 9.7 473.5 737.9 0.0 0.7 0.0 11.2 0 39 c1t5000C50055F9A607d0</div><div> 55.8 20.2 457.3 708.7 0.0 0.7 0.0 9.9 0 40 c1t5000C50055F8CDA7d0</div><div> 57.8 28.6 487.0 796.1 0.0 0.9 0.0 9.9 0 45 c1t5000C50055E65877d0</div>
<div> 60.8 27.1 572.6 823.7 0.0 0.8 0.0 8.8 0 41 c1t5000C50055F9E7D7d0</div><div> 55.8 21.1 478.2 766.6 0.0 0.7 0.0 9.7 0 40 c1t5000C50055FA0AF7d0</div><div> 57.0 22.8 528.3 724.5 0.0 0.8 0.0 9.6 0 41 c1t5000C50055F9FE87d0</div>
<div> 56.2 10.8 465.2 715.6 0.0 0.7 0.0 10.4 0 38 c1t5000C50055F9F91Bd0</div><div> 59.2 29.4 524.6 740.9 0.0 0.8 0.0 8.9 0 41 c1t5000C50055F9FEABd0</div><div> 57.3 30.7 496.7 788.3 0.0 0.8 0.0 9.1 0 42 c1t5000C50055F9F63Bd0</div>
<div> 55.5 16.3 461.9 652.9 0.0 0.7 0.0 10.1 0 39 c1t5000C50055F9F3EBd0</div><div> 57.2 22.1 495.1 701.1 0.0 0.8 0.0 9.8 0 41 c1t5000C50055F9F80Bd0</div><div> 59.5 30.2 543.1 741.8 0.0 0.9 0.0 9.6 0 45 c1t5000C50055F9FB8Bd0</div>
<div> 56.5 25.1 515.4 786.9 0.0 0.7 0.0 8.6 0 38 c1t5000C50055F9F92Bd0</div><div> 61.8 12.5 540.6 790.9 0.0 0.8 0.0 10.3 0 41 c1t5000C50055F8905Fd0</div><div> 57.0 19.8 521.0 774.3 0.0 0.7 0.0 9.6 0 39 c1t5000C50055F8D48Fd0</div>
<div> 56.3 16.3 517.7 724.7 0.0 0.7 0.0 9.9 0 38 c1t5000C50055F9F89Fd0</div><div> 57.0 13.4 504.5 790.5 0.0 0.8 0.0 10.7 0 40 c1t5000C50055F9EF2Fd0</div><div> 55.0 26.1 477.6 845.2 0.0 0.7 0.0 8.3 0 36 c1t5000C50055F8C3ABd0</div>
<div> 57.8 14.1 518.7 740.7 0.0 0.8 0.0 10.8 0 41 c1t5000C50055E66053d0</div><div> 55.9 20.8 490.2 715.7 0.0 0.7 0.0 9.0 0 37 c1t5000C50055E66503d0</div><div> 57.0 24.1 509.7 806.9 0.0 0.8 0.0 10.0 0 41 c1t5000C50055F9D3E3d0</div>
<div> 59.1 29.2 504.1 740.9 0.0 0.8 0.0 9.3 0 44 c1t5000C50055F84FB7d0</div><div> 54.4 16.3 449.5 652.9 0.0 0.7 0.0 10.4 0 39 c1t5000C50055F8E017d0</div><div> 57.8 28.4 503.3 796.1 0.0 0.9 0.0 10.1 0 45 c1t5000C50055E579F7d0</div>
<div> 58.2 24.9 502.0 841.7 0.0 0.8 0.0 9.2 0 40 c1t5000C50055E65807d0</div><div> 58.2 20.7 513.4 766.6 0.0 0.8 0.0 9.8 0 41 c1t5000C50055F84A97d0</div><div> 56.5 24.9 508.0 857.5 0.0 0.8 0.0 9.2 0 40 c1t5000C50055F87D97d0</div>
<div> 53.4 13.5 449.9 790.5 0.0 0.7 0.0 10.7 0 38 c1t5000C50055F9F637d0</div><div> 57.0 11.8 503.0 790.9 0.0 0.7 0.0 10.6 0 39 c1t5000C50055E65ABBd0</div><div> 55.4 9.6 461.1 737.9 0.0 0.8 0.0 11.6 0 40 c1t5000C50055F8BF9Bd0</div>
<div> 55.7 19.7 484.6 774.3 0.0 0.7 0.0 9.9 0 40 c1t5000C50055F8A22Bd0</div><div> 57.6 27.1 518.2 823.7 0.0 0.8 0.0 8.9 0 40 c1t5000C50055F9379Bd0</div><div> 59.6 17.0 528.0 756.1 0.0 0.8 0.0 10.1 0 41 c1t5000C50055E57A5Fd0</div>
<div> 61.2 10.8 530.0 715.6 0.0 0.8 0.0 10.7 0 40 c1t5000C50055F8CCAFd0</div><div> 58.0 30.8 493.3 788.3 0.0 0.8 0.0 9.4 0 43 c1t5000C50055F8B80Fd0</div><div> 56.5 19.9 490.7 708.7 0.0 0.8 0.0 10.0 0 40 c1t5000C50055F9FA1Fd0</div>
<div> 56.1 22.4 484.2 701.1 0.0 0.7 0.0 9.5 0 39 c1t5000C50055E65F0Fd0</div><div> 59.2 14.6 560.9 765.1 0.0 0.7 0.0 9.8 0 39 c1t5000C50055F8BE3Fd0</div><div> 57.9 16.2 546.0 724.7 0.0 0.7 0.0 10.1 0 40 c1t5000C50055F8B21Fd0</div>
<div> 59.5 30.0 553.2 741.8 0.0 0.9 0.0 9.8 0 45 c1t5000C50055F8A46Fd0</div><div> 57.4 22.5 504.0 724.5 0.0 0.8 0.0 9.6 0 41 c1t5000C50055F856CFd0</div><div> 58.4 24.6 531.4 786.9 0.0 0.7 0.0 8.4 0 38 c1t5000C50055E6606Fd0</div>
<div> 511.0 161.4 7572.1 11260.1 0.0 0.3 0.0 0.4 0 14 c2</div><div> 252.3 20.1 3776.3 458.9 0.0 0.1 0.0 0.2 0 6 c2t500117310015D579d0</div><div> 258.8 18.0 3795.7 350.0 0.0 0.1 0.0 0.2 0 6 c2t50011731001631FDd0</div>
<div> 0.0 123.4 0.0 10451.1 0.0 0.1 0.0 1.0 0 3 c2t5000A72A3007811Dd0</div><div> 0.2 16.1 1.9 56.7 0.0 0.0 0.0 0.0 0 0 c4</div><div> 0.2 8.1 1.6 28.3 0.0 0.0 0.0 0.0 0 0 c4t0d0</div>
<div> 0.0 8.1 0.3 28.3 0.0 0.0 0.0 0.0 0 0 c4t1d0</div><div> 495.6 163.6 7168.9 11290.3 0.0 0.2 0.0 0.4 0 14 c12</div><div> 0.0 123.4 0.0 10451.1 0.0 0.1 0.0 1.0 0 3 c12t5000A72B300780FFd0</div>
<div> 248.2 18.1 3645.8 323.0 0.0 0.1 0.0 0.2 0 5 c12t500117310015D59Ed0</div><div> 247.4 22.1 3523.1 516.2 0.0 0.1 0.0 0.2 0 6 c12t500117310015D54Ed0</div><div> 0.2 14.8 1.9 56.7 0.0 0.0 0.6 0.1 0 0 rpool</div>
<div> 3883.5 1357.7 40141.6 60739.5 22.8 38.6 4.4 7.4 54 100 tank</div></div><div><br></div><div>It is very busy with alot of wait % and higher asvc_t (2011% busy on c1?!). I'm assuming resilvers are alot more aggressive than scrubs.</div>
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<div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<div style="word-wrap:break-word"><div><div></div></div><div>There are many variables here, the biggest of which is the current non-scrub load.</div></div></blockquote></div></blockquote><div>
<br></div></div><div>I might have lost 2 weeks of scrub time, depending on whether the scrub will resume where it left off. I'll update when I can. </div><div> </div></div>
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