<div dir="ltr">General warning: have a look at power safety issues before building all-SSD pools. Unless the drive is power-safe, you may find that writes acknowledged by the controller that are meant to be flushed aren't. There's been a reasonable amount of research, published on this, including one paper by Luke Kenneth Casson Leighton and another supported by HP presented at FAST, and the general conclusion is that consumer SSDs don't get this right. Intel had some models that did this, but these features now appear to be exclusive to their data center products. Hitachi does not claim that the 850s are power safe, so they are only suitable for L2ARC.<br><br>Have you had a look at FMA telemetry for the devices?<br><br>Cheers,<div>Bayard</div></div><div class="gmail_extra"><br><div class="gmail_quote">On 25 September 2014 23:46, Andrew M. Hettinger <span dir="ltr"><<a href="mailto:AHettinger@prominic.net" target="_blank">AHettinger@prominic.net</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div>
<p><font face="sans-serif">I'm presently running tests on a pool using 3x Samsung 850 SSDs on a LSI-9211-8i (IT) contoller. I thought I'd try seperating the intent log to see if lowering the write amplification on the pool-drives would help, so I added another matching SSD for that, but under load I still seem to get extensive checksum errors. Does anyone have any ideas as to what would be causing this?</font><br>
<br>
<font face="DejaVu Sans Mono"> pool: test-array</font><br>
<font face="DejaVu Sans Mono"> state: DEGRADED</font><br>
<font face="DejaVu Sans Mono">status: One or more devices has experienced an unrecoverable error. An</font><br>
<font face="DejaVu Sans Mono"> attempt was made to correct the error. Applications are unaffected.</font><br>
<font face="DejaVu Sans Mono">action: Determine if the device needs to be replaced, and clear the errors</font><br>
<font face="DejaVu Sans Mono"> using 'zpool clear' or replace the device with 'zpool replace'.</font><br>
<font face="DejaVu Sans Mono"> see: <a href="http://illumos.org/msg/ZFS-8000-9P" target="_blank">http://illumos.org/msg/ZFS-8000-9P</a></font><br>
<font face="DejaVu Sans Mono"> scan: scrub repaired 0 in 0h0m with 0 errors on Wed Sep 24 18:20:56 2014</font><br>
<font face="DejaVu Sans Mono">config:</font><br>
<br>
<font face="DejaVu Sans Mono"> NAME STATE READ WRITE CKSUM</font><br>
<font face="DejaVu Sans Mono"> test-array DEGRADED 0 0 0</font><br>
<font face="DejaVu Sans Mono"> mirror-0 DEGRADED 0 0 0</font><br>
<font face="DejaVu Sans Mono"> c0t50025388700060D4d0 DEGRADED 0 0 155 too many errors</font><br>
<font face="DejaVu Sans Mono"> c0t50025388700060AEd0 DEGRADED 0 0 149 too many errors</font><br>
<font face="DejaVu Sans Mono"> c0t50025388700060C2d0 DEGRADED 0 0 174 too many errors</font><br>
<font face="DejaVu Sans Mono"> logs</font><br>
<font face="DejaVu Sans Mono"> c0t50025388A067DBE9d0 ONLINE 0 0 0</font><br>
<br>
<font face="DejaVu Sans Mono">errors: No known data errors</font><br>
<font face="DejaVu Sans Mono"> ---- errors ---</font><br>
<font face="DejaVu Sans Mono"> s/w h/w trn tot device</font><br>
<font face="DejaVu Sans Mono"> 0 2 6 8 c0t50025388700060D4d0</font><br>
<font face="DejaVu Sans Mono"> 0 0 0 0 c0t50025388700060AEd0</font><br>
<font face="DejaVu Sans Mono"> 0 0 0 0 c0t50025388700060C2d0</font><br>
<font face="DejaVu Sans Mono"> 0 0 0 0 c0t50025388A067DBE9d0</font><br>
<br>
<br>
<font face="sans-serif">Andrew Hettinger<br>
<a href="http://Prominic.NET" target="_blank">http://Prominic.NET</a> | Skype: AndrewProminic<br>
Tel: <a href="tel:866.339.3169" value="+18663393169" target="_blank">866.339.3169</a> (toll free) -or- <a href="tel:1.217.356.2888%20x.%20110" value="+12173562888" target="_blank">1.217.356.2888 x. 110</a> (int'l)<br>
Fax: <a href="tel:866.372.3356" value="+18663723356" target="_blank">866.372.3356</a> (toll free) -or- <a href="tel:1.217.356.3356" value="+12173563356" target="_blank">1.217.356.3356</a> (int'l)</font></p></div><br>_______________________________________________<br>
oi-dev mailing list<br>
<a href="mailto:oi-dev@openindiana.org">oi-dev@openindiana.org</a><br>
<a href="http://openindiana.org/mailman/listinfo/oi-dev" target="_blank">http://openindiana.org/mailman/listinfo/oi-dev</a><br></blockquote></div><br></div>