| From: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
|---|---|
| To: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
| Cc: | Aidan Van Dyk <aidan(at)highrise(dot)ca>, Gregory Stark <stark(at)enterprisedb(dot)com>, Martijn van Oosterhout <kleptog(at)svana(dot)org>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Greg Stark <greg(dot)stark(at)enterprisedb(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Block-level CRC checks |
| Date: | 2008-11-13 19:54:19 |
| Message-ID: | 491C85EB.7020708@enterprisedb.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
Alvaro Herrera wrote:
> XFS, for example, zeroes out during recovery any block
> that was written to but not fsync'ed before a crash. This means that if
> we change a hint bit after a checkpoing and mark the page dirty, the
> system can write the page. Suppose we crash at this point. On
> recovery, XFS will zero out the block, but there will be nothing with
> which to recovery it, because there's no backup block ...
Really? That would mean that you're prone to lose data if you run
PostgreSQL on XFS, even without the CRC patch.
I doubt that's true, though. Google found this:
http://marc.info/?l=linux-xfs&m=122549156102504&w=2
See the bottom of that mail.
Although, Florian Weimer suggested earlier in this thread that IBM DTLA
disks have exactly that problem; a sector could be zero-filled if the
write is interrupted.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Michael Meskes | 2008-11-13 19:55:15 | gram.y => preproc.y |
| Previous Message | Tom Lane | 2008-11-13 19:53:15 | Re: Simple postgresql.conf wizard |