Feasability of VERY large ext3 file system?
arechenberg at shermfin.com
Thu Dec 5 07:02:01 CST 2002
I posed this question (data=ordered being faster) on the ext3 mailing
list a few weeks ago and Stephen C. Tweedie (I believe one of the
developers, or THE developer of ext3) replied with the following:
> [ext3 is] particularly suited when you have applications performing
> transactions --- ie. when they are using O_SYNC or fsync() to flush
> data to disk. The data-journaling allows the data to be written
> sequentially in the log.
> However, _eventually_ it will still need to write the data elsewhere
> on disk (unless it rapidly gets deleted), so the effect is really to
> mitigate the cost of the application synchronisation, rather than
> anything else.
> So it really depends very much on what the application is doing
> whether or not this makes much of a difference.
You'll have to see what your application is doing WRT on-disk
transactions to see if data=journal will give you any performance
From: nathan r. hruby [mailto:nathan at drama.uga.edu]
Sent: Wednesday, December 04, 2002 5:20 PM
To: jason andrade
Cc: Ed Griffin; Steve_Boley at dell.com; linux-poweredge at dell.com
Subject: RE: Feasability of VERY large ext3 file system?
On Thu, 5 Dec 2002, jason andrade wrote:
> On Wed, 4 Dec 2002, Ed Griffin wrote:
> > can the filesystem options you mentioned (rw,data=writeback) be used
> > these??? From what I remember when setting these systems up, I
> > change any parameters of the RAID controllers themselves, but I do
> > something about a writeback option. Should I have???
> someone correct me if i'm wrong please, but i thought the above is
> the way the journal works so you are increasing your risk in the event
> unexpected power outage (unlikely i know nowadays with dual power
> into different UPSes on different circuits..). personally with the
> filesystems i am more cautious/conservative than normal because of the
> much larger data set that can be lost now (and the time to recover
It is, but only a little. Ordered mode doesn't make any promises about
data intergrity it just does its darned best to keep your data happy.
Ironically, I found this article that states the oppisite (data=journal
faster than ordered and writeback)
If anyone has any comments, thoughts or experince on the above link, I'd
be interested to hear them.
nathan hruby <nathan at drama.uga.edu>
computer services specialist
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