On Wed, Oct 5, 2016 at 1:29 PM, Gandalf Corvotempesta < gandalf.corvotempesta at gmail.com> wrote:> Il 30 set 2016 1:46 PM, "Gandalf Corvotempesta" < > gandalf.corvotempesta at gmail.com> ha scritto: > > > I was thinking about creating one or more raidz2 to use as bricks, with > 2 ssd. One small partition on these ssd would be used as a mirrored SLOG > and the other 2 would be used as standalone arc cache. will this worth the > use of SSD or would be totally useless with gluster? > > > > I don't know if use gluster hot tiering or let zfs manage everything > > > > No advice here? > I'm still looking for advice, i would like start the new cluster with the > new year and i still have to choose and buy hardware >The mirrored slog will be useful. Depending on what you put on the pool l2arc may not get used much. I removed mine as it got such a low hit rate serving VM's. I also re-did my bricks from raidz2 to using mirrored pairs. I felt that with 3 server redundancy the performance benefits from a more raid10 type layout would be more useful than raidz2 for the pool. I could see where some might want more security though in their data I myself wouldn't experiment with tiering for my use case. .I haven't heard any positive feedback from anyone using tiering yet to want to be testing.> > _______________________________________________ > Gluster-users mailing list > Gluster-users at gluster.org > http://www.gluster.org/mailman/listinfo/gluster-users >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://www.gluster.org/pipermail/gluster-users/attachments/20161005/d701ad38/attachment.html>
2016-10-05 20:50 GMT+02:00 David Gossage <dgossage at carouselchecks.com>:> The mirrored slog will be useful. Depending on what you put on the pool > l2arc may not get used much. I removed mine as it got such a low hit rate > serving VM's.I'll use shards. The most accessed shard isn't cached in L2ARC? I'll also other pools for plain file hosting (websites and so one). In this case an L2ARC would be usefull. I think. Is possible to share the same L2ARC from multiple ZFS pools ?> I also re-did my bricks from raidz2 to using mirrored pairs. I felt that > with 3 server redundancy the performance benefits from a more raid10 type > layout would be more useful than raidz2 for the pool. I could see where > some might want more security though in their dataSo, you removed the RAIDZ2 and created multiple mirrors (like RAID-1) ? I can do that, but is really a waste of space. In a replica 3, your are replicating 6 times. Or did you create a RAID-10 ? I really hate RAID-10. If you loose 2 disks from the same mirror (and in a 12 disks server this could be frequent) you loose the whole pool and rebuilding time from the network could be.............. HUGE. Try to rebuild 24TB from network. In a perfect world, this require at least 24.000/1.24 = 19.200 seconds. more than 5 hours by using the whole 10GB network only for healing. I feel more confortable with 2xRAIDZ-2 than a RAID10 By using SLOG, the RAIDZ2 write penalty should be removed as gluster always write to SLOG (SSD) and to the RAIDZ-2 only in background, right? Is possible to change the ZIL flush timeout from 5 seconds to something bigger as i'm using SSD with power-loss protection ?