`<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Apr 6, 2015 at 8:41 AM, Chris Nagele <span dir="ltr"><<a href="mailto:nagele@wildbit.com" target="_blank">nagele@wildbit.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Thanks everyone. Regarding the expanders, our 4U servers are on the<br>
following chassis:<br>
<br>
<a href="http://www.supermicro.com/products/chassis/4U/846/SC846E16-R1200.cfm" target="_blank">http://www.supermicro.com/products/chassis/4U/846/SC846E16-R1200.cfm</a><br>
<br>
We are using all SAS disks, except for the SSDs. How big is the risk<br>
here when it comes to SAS -> SATA conversion? Our newer servers have<br>
direct connections on each lane to the disk.<br></blockquote><div><br></div><div>There are A LOT of opinions on this. What I have done that has worked extremely well was use 70 Samsung 840 Pro SSD with LSI interposers in Supermicro chassis. There were a couple early failures of the interposers but it has been rock solid ever since. mpt_sas blue chunks and panic'd the system on one. On another one I caught it in action and doing a 'zpool offline {device}' kept everything running without a hitch. <br><br></div><div>I run with ZIL off because this is used entirely for scratch data and virtual machines that can be redeployed in minutes. It would be sync safe with the addition of some good log devices. <br><br></div><div>I'm not sure if the interposers increased stability or it has simply been the quality of the Samsung SSD.<br><br></div><div>-Chip<br></div><div><br><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<span class="HOEnZb"><font color="#888888"><br>
Chris<br>
</font></span><span class="im HOEnZb"><br>
Chris Nagele<br>
Co-founder, Wildbit<br>
Beanstalk, Postmark, <a href="http://dploy.io" target="_blank">dploy.io</a><br>
<br>
<br>
</span><div class="HOEnZb"><div class="h5">On Sat, Apr 4, 2015 at 7:18 PM, Doug Hughes <<a href="mailto:doug@will.to">doug@will.to</a>> wrote:<br>
><br>
> We have a couple of machines with all SSD pool (~6-10 Samsung 850 pro is the<br>
> current favorite). They work great for IOPS. Here's my take.<br>
> 1) you don't need a dedicated zil. Just let the zpool intersperse it amongst<br>
> the existing zpool devices. They are plenty fast enough.<br>
> 2) you don't need an L2arc for the same reason. a smaller number of<br>
> dedicated devices would likely cause more of a bottleneck than serving off<br>
> the existing pool devices (unless you were to put it on one of those giant<br>
> RDRAM things or similar, but that adds a lot of expense)<br>
><br>
><br>
><br>
><br>
><br>
> On 4/4/2015 3:07 PM, Chris Nagele wrote:<br>
><br>
> We've been running a few 4U Supermicro servers using ZeusRAM for zil and<br>
> SSDs for L2. The main disks are regular 1TB SAS.<br>
><br>
> I'm considering moving to all SSD since the pricing has dropped so much.<br>
> What things should I know or do when moving to all SSD pools? I'm assuming I<br>
> don't need L2 and that I should keep the ZeusRAM. Should I only use certain<br>
> types of SSDs?<br>
><br>
> Thanks,<br>
> Chris<br>
><br>
><br>
> --<br>
><br>
> Chris Nagele<br>
> Co-founder, Wildbit<br>
> Beanstalk, Postmark, <a href="http://dploy.io" target="_blank">dploy.io</a><br>
><br>
><br>
><br>
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