Re: ZFS



I use ZFS since 7.0-RELEASE. I'm currently using latest stable.
Ok the load is not as a production one, as the box is used as a home server (NAS), but the hardware is limited too (only 512MB of RAM, mono-core A64 3200+, motherborad integrated sata controler).
I tried to stress the filesystem a bit with multiple simultaneous rsyncs. No glitches. The only failures was when swap was on a zvol instead of the system drive. Even with more ram, it regularely ended in panics or deadlocks (most of the time, deadlocks) under "high" load.

Not sure of anything here, but you might want to try with non-zfs swap - on another drive(s) or dedicated slices ?

Yep, I think I'm going to use a separate slice
for the pool, mounting into the respective jails
only the needed filesystems:

mypool/mail into /jails/mail/maildataroot
mypool/db into /jails/web/mysql-bup-slave

(or sort of)

and then use frequent snapshots for mypool/mail
(even hourly or so), and for the database,
a few times per day mysql-backup-slave.sh stop,
zfs snapshot mypool/db, mysql-backup-slave.sh start..

the mysql slave snapshotting is really a goodness
which I've used on a SunOS with zfs and really
rocks. So I never shutdown the master, the slave
goes down only a few seconds, and the database
filesystem is consistent and synced.

In the current case, I think it is not only a feature
but also a must: _If_ the host deadlocks and
mysql fails to sync, at least I have a working
snapshot of the data. I wouldn't put the master itself
on zfs for now, but if all goes well for a while,
why not.

BTW: while sync does not work anymore in a deadlock situation,
I've seen that fsync mostly still does.
So something like find /var/db/mysql -type f -exec fsync {} \;
can save your files if the db is running on UFS..

Thanx & Regards!


Lorenzo


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