On 22.07.2015 3:17, Kir Kolyshkin wrote:
simfs need for using OpenVZ with ZFS
Other "why not simfs" considerations are listed at
http://openvz.org/Ploop/Why#Before_ploop
there are three levels:
1. before ploop: simfs over ext4
2. with ploop: ext4 over ploop over ext4
3. after ploop: simfs over ZFS
comparing (1) and (2) - ploop win,
but comparing (2) with (3) - simfs win!
For one thing, I wonder how you use live migration with zfs,
can you please tell us?
I don't use live migration at all.
several reasons:
1) currently even suspend/resume not work reliable:
https://bugzilla.openvz.org/show_bug.cgi?id=2470
- I can't suspend and resume containers without bugs.
and as result - I also can't use it for live migration.
2) I see in google many bugreports about this feature:
"openvz live migration kernel panic" - so I prefer make
planned downtime of containers at the night instead
of unexpected and very painful kernel panics and
complete reboots in the middle of the working day.
(with data lost, data corruption and other "amenities")
3) my current hosting provider don't allow migrating
of IP between different servers in his datacenter.
4) from technical point of view - it is possible
to do live migration using ZFS, so "live migration"
currently is only one advantage of ploop over ZFS
- but this is not something like "killer feature",
but only temporary situation. In near future this
imbalance can be fixed, if anyone really need
live migration and ZFS with OpenVZ.
(using ZFS snapshots, for example)
And, as result, in near future:
"simfs over ZFS" always better (for app hosting)
than "ext4 over ploop over ext4"
- so it will be no reasons at all to use ploop.
Also ploop is not in mainline kernel
and probably newer it will be there. (?)
Docker already contains ZFS storage driver.
ZFS already can be used with mainline kernel.
With each new version - ZFS is better and better.
ZFS is really "The Last Word in File Systems",
and now you can just use it for free,
without reinventing the wheel.
OpenVZ + ZFS or Virtuozzo + ZFS == atom bomb,
killer feature with horrible devastation power.
Or - you just forcing users to migrate from OpenVZ
to CentOS+KVM over ZFS and/or CentOS+Docker over ZFS.
--
Best regards,
Gena
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