Arf forgot to mention that I’ll do a software mdadm RAID 1 with both sda1 and sdb1 and put the OS on this. The rest (sda2 and sdb2) will go for the journals. @James: I think that Gandalf’s main idea was to save some costs/space on the servers so having dedicated disks is not an option. (that what I understand from your comment “have the OS somewhere else” but I could be wrong) –––– Sébastien Han Cloud Engineer "Always give 100%. Unless you're giving blood.” Phone: +33 (0)1 49 70 99 72 Mail: sebastien.han@xxxxxxxxxxxx Address : 10, rue de la Victoire - 75009 Paris Web : www.enovance.com - Twitter : @enovance On 05 Dec 2013, at 16:02, James Pearce <james@xxxxxxxxxxxx> wrote: > Another option is to run journals on individually presented SSDs, in a 5:1 ratio (spinning-disk:ssd) and have the OS somewhere else. Then the failure domain is smaller. > > Ideally implement some way to monitor SSD write life SMART data - at least it gives a guide as to device condition compared to its rated life. That can be done with smartmontools, but it would be nice to have it on the InkTank dashboard for example. > > > On 2013-12-05 14:26, Sebastien Han wrote: >> Hi guys, >> >> I won’t do a RAID 1 with SSDs since they both write the same data. >> Thus, they are more likely to “almost” die at the same time. >> >> What I will try to do instead is to use both disk in JBOD mode or >> (degraded RAID0). >> Then I will create a tiny root partition for the OS. >> >> Then I’ll still have something like /dev/sda2 and /dev/sdb2 and then >> I can take advantage of the 2 disks independently. >> The good thing with that is that you can balance your journals across both SSDs. >> From a performance perspective this is really good. >> The bad thing as always is that if you loose a SSD you loose all the >> journals attached to it. >> >> Cheers. >> >> –––– >> Sébastien Han >> Cloud Engineer >> >> "Always give 100%. Unless you're giving blood.” >> >> Phone: +33 (0)1 49 70 99 72 >> Mail: sebastien.han@xxxxxxxxxxxx >> Address : 10, rue de la Victoire - 75009 Paris >> Web : www.enovance.com - Twitter : @enovance >> >> On 05 Dec 2013, at 10:53, Gandalf Corvotempesta >> <gandalf.corvotempesta@xxxxxxxxx> wrote: >> >>> 2013/12/4 Simon Leinen <simon.leinen@xxxxxxxxx>: >>>> I think this is a fine configuration - you won't be writing to the root >>>> partition too much, outside journals. We also put journals on the same >>>> SSDs as root partitions (not that we're very ambitious about >>>> performance...). >>> >>> Do you suggest a RAID1 for the OS partitions on SSDs ? Is this safe or >>> a RAID1 will decrease SSD life? >>> _______________________________________________ >>> ceph-users mailing list >>> ceph-users@xxxxxxxxxxxxxx >>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> >> >> _______________________________________________ >> ceph-users mailing list >> ceph-users@xxxxxxxxxxxxxx >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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