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<p>Il 06/11/2016 03:37, David Gossage ha scritto:<br>
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cite="mid:CAJXeYEWk0ww8PC6XpNGVkEZrGsHZqf0+yi0eTYWfehFW3RUQ1g@mail.gmail.com"
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<div class="gmail_quote">The only thing you gain with raidz1 I
think is maybe more usable space. Performance in general
will not be as good, and whether the vdev is mirrored or z1
neither can survive 2 drives failing. In most cases the z10
will rebuild faster with less impact during rebuild. If you
are already using gluster 3 node replicate as VM practices
suggest then you are already pretty well protected if you
lose the wrong 2 drives as well.<br>
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<br>
Ok, i'll try again. I'm <b>not</b> talking about a single RAIDZ1
for the whole server.<br>
<br>
Let's assume a 12 disks server. 4TB each. Raw space = 4TB*12 = 48TB<br>
<br>
You can do one of the following:<br>
1) <b>a single RAIDZ10</b>, using all disks, made up by 6 RAIDZ1
mirrors. usable space=4TB*6 = 24TB<br>
2) <b>6 RAIDZ1 mirrors</b>. usable space=4TB*6 = 24TB<br>
<br>
You'll get the same usable space for both solution.<br>
<br>
Now you have gluster, so you have at least 2 more servers in
"identical" configuration.<br>
<br>
With solution 1, you can loose only 1 disk for each pair. If you
loose 2 disks from the same pair, you loose the whole RAIDZ10 and
you have<br>
to heal 24TB from the network.<br>
<br>
With solution 2, you can loose the same number of disks, but if you
loose 1 mirror at once, you only have to heal that mirror from the
network, only 4TB.<br>
<br>
* IOPS should be the same, as Gluster will 'aggragate' each pair in
a single volume, like a RAID10 does, but you get much more speed
during an healing.<br>
* Resilvering time is the same, as ZFS has to resilver only the
failed disk with both solutions.<br>
<br>
What i'm saying is to skip the "RAID0" part and use gluster as
aggragator. Is much more secure and faster to recover in case of
multiple failures.<br>
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