to gmirror or to ZFS

Nikos Vassiliadis nvass at
Tue Jul 16 23:08:44 UTC 2013

On 07/16/13 21:27, Johan Hendriks wrote:
> Op dinsdag 16 juli 2013 schreef Charles Swiger (cswiger at het
> volgende:
>> Hi--
>> On Jul 16, 2013, at 10:33 AM, Johan Hendriks <joh.hendriks at<javascript:;>>
>> wrote:
>> [ ... ]
>>> I would us a zfs for the os.
>>> I have a couple of servers that did not survive a power failure with
>>> gmirror.
>>> The problems i had was when the power failed one disk was in a rebuilding
>>> state and then when the background fsck started or was busy for some time
>>> it would crash the whole server.
>> Well, "don't do that".  :-)
> When the server reboots because of a powerfailure at night, then it boots.
> Then it starts to rebuild the mirror on its own, and later the fsck kicks
> in.
> Not much i can do about it.

You could add geom_journal which will minimize the time of fsck to a 
second or something like that. Then you don't have to use background 
fsck anymore.

Actually geom_journal's manual page mentions an interesting
side-effect of geom_journal over a geom_mirror:

	you can turn off component synchronization.

Geom_journal will re-play last writes so whatever was
changed just before the crash will be re-written to both disks.
I haven't used this but it makes sense in theory.

> Maybe i should have done it without the automatic attachment for a new
> device.

I always turn off automatic synchronization or stale components
as well.

It seems to me that people don't really use geom_journal
or maybe they just don't talk about it like it's some
sort of secret:)

just my two cents,


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