<div dir="ltr"><div class="gmail_extra"><div><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div>On Wed, Oct 5, 2016 at 2:14 PM, Gandalf Corvotempesta <span dir="ltr"><<a href="mailto:gandalf.corvotempesta@gmail.com" target="_blank">gandalf.corvotempesta@gmail.com</a>></span> wrote:<br></div></div></div></div><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">2016-10-05 20:50 GMT+02:00 David Gossage <<a href="mailto:dgossage@carouselchecks.com">dgossage@carouselchecks.com</a>>:<br>
> The mirrored slog will be useful. Depending on what you put on the pool<br>
> l2arc may not get used much. I removed mine as it got such a low hit rate<br>
> serving VM's.<br>
<br>
I'll use shards. The most accessed shard isn't cached in L2ARC?<br></blockquote><div><br></div><div>L2ARC filled up some, but the usage hit ratios never hit above 8% so I just freed it up fro the system to use as it would. Haven;t noticed any difference since doing that. </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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I'll also other pools for plain file hosting (websites and so one). In<br>
this case an L2ARC would be usefull. I think.<br>
Is possible to share the same L2ARC from multiple ZFS pools ?<br></blockquote><div><br></div><div>L2ARC is per pool I believe. </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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> I also re-did my bricks from raidz2 to using mirrored pairs. I felt that<br>
> with 3 server redundancy the performance benefits from a more raid10 type<br>
> layout would be more useful than raidz2 for the pool. I could see where<br>
> some might want more security though in their data<br>
<br>
So, you removed the RAIDZ2 and created multiple mirrors (like RAID-1) ?<br>
I can do that, but is really a waste of space. In a replica 3, your<br>
are replicating 6 times.<br>
Or did you create a RAID-10 ? I really hate RAID-10. If you loose 2<br>
disks from the same mirror<br>
(and in a 12 disks server this could be frequent) you loose the whole<br>
pool and rebuilding time from<br>
the network could be.............. HUGE. Try to rebuild 24TB from<br>
network. In a perfect world, this require<br>
at least 24.000/1.24 = 19.200 seconds. more than 5 hours by using the<br>
whole 10GB network only for healing.<br>
<br>
I feel more confortable with 2xRAIDZ-2 than a RAID10<br></blockquote><div><br></div><div>That's fine. For my VM case I currently only use around 1TB per host so worst case scenario I found was if one server is down I could rebuild brick overnight. For your case that's not as easy. Also for me I use 1TB disks in my mirrors so if one drive goes down it's not that long to re-sync it on replace. Reduces my chance to have 2 disks in same mirror die at same time a little bit.</div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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By using SLOG, the RAIDZ2 write penalty should be removed as gluster<br>
always write to SLOG (SSD) and to the RAIDZ-2 only in background,<br>
right?<br>
Is possible to change the ZIL flush timeout from 5 seconds to<br>
something bigger as i'm using SSD with power-loss protection ?<br></blockquote><div><br></div><div>I believe you can though I haven't played with that. </div></div><br></div></div>