Dne 13.9.2017 v 00:55 Gionatan Danti napsal(a):
Il 13-09-2017 00:41 Zdenek Kabelac ha scritto:
There are maybe few worthy comments - XFS is great on stanadar big
volumes, but there used to be some hidden details when used on thinly
provisioned volumes on older RHEL (7.0, 7.1)
So now it depend how old distro you use (I'd probably highly recommend
upgrade to RH7.4 if you are on RHEL based distro)
Sure.
Basically 'XFS' does not have similar 'remount-ro' on error behavior
which 'extX' provides - but now XFS knows how to shutdown itself when
meta/data updates starts to fail - although you may need to tune some
'sysfs' params to get 'ideal' behavior.
True, with a catch: with the default data=ordered option, even ext4 does *not*
remount read only when data writeout fails. You need to use both
"errors=remount-ro" and "data=journal" which basically nobody uses.
Personally for smaller sized thin volumes I'd prefer 'ext4' over XFS -
unless you demand some specific XFS feature...
Thanks for the input. So, do you run your ext4 filesystem with data=journal?
How they behave performane-wise?
As said data=journal is big performance killer (especially on SSD)
Personally I prefer early 'shutdown' in case the situation becomes critical
(i.e. 95% fullness because some process gets crazy)
But you can write any advanced scripting logic to suit best your needs -
i.e. replace all thins on thin-pool with 'error' target....
(which is as simple as using 'dmsetup remove --force'.... - this will
make all future read/writes giving you i/o errors....)
Simply do all in user-space early enough before thin-pool can ever get NEAR t
being 100% full - reaction is really quick - and you have at least 60seconds
to solve the problem in worst case.....
Regards
Zdenek
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