Re: data=writeback - Mailing list pgsql-performance

From Bruce Momjian
Subject Re: data=writeback
Date
Msg-id 200404081452.i38EqXV20923@candle.pha.pa.us
Whole thread Raw
In response to Re: data=writeback  (<list@1006.org>)
List pgsql-performance
list@1006.org wrote:
> > When I give "mount" at the command line, everything looks just fine :
> >
> > /dev/sda2 on / type ext3 (rw,noatime,data=ordered)
> > none on /proc type proc (rw)
> > usbdevfs on /proc/bus/usb type usbdevfs (rw)
> > /dev/sda1 on /boot type ext3 (rw,noatime,data=ordered)
> > none on /dev/pts type devpts (rw,gid=5,mode=620)
> > none on /dev/shm type tmpfs (rw)
> > /dev/sdb1 on /usr/local/pgsql type ext3 (rw,noatime,data=writeback)
> > /dev/sda3 on /usr/local/pgsql/wal type ext3 (rw,noatime,data=ordered)
> >
> > It looks like the labels are not really used, just the mount-points. Or
> > could this cause other problems I am not aware of? Everything seems to
> > be working just fine, for several months now...
>
> Probably /dev/sdb1 and /dev/sda3 have the same labels and mount
> simply mounts them in a consistent way according to some logic
> we're not aware of.
>
> I'd say: if it works don't touch it ;)
>
> What remains unresolved is the question whether data=writeback is ok
> or not. We'll see if somebody has more information on that one...

Should be fine.  We don't continue until fsync() writes all the data.
We don't care what order it is written in, just that is all written
before we continue.

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

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