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RE: less data lost, more fs corruption

To: "'linux-xfs@xxxxxxxxxxx '" <linux-xfs@xxxxxxxxxxx>
Subject: RE: less data lost, more fs corruption
From: Scott Smyth <SSmyth@xxxxxxxxxx>
Date: Tue, 13 Feb 2001 19:14:41 -0800
Sender: owner-linux-xfs@xxxxxxxxxxx

I have been seeing the same problem in very specific cases of
using software RAID 1 and accessing a Samba share with smbclient.
I never see it any other time and not every time in this
configuration.  In addition, it seems to help reproduce this
if the RAID 1 is resyncing and smbclient is doing more than
16 clients in a 64 MB configuration on the server.  Therefore,
it is doing some swap.

I applied Andy's patch and am trying to reproduce again.

thanks, Scott

-----Original Message-----
From: utz lehmann
To: Steve Lord
Cc: linux-xfs@xxxxxxxxxxx
Sent: 2/13/01 5:52 PM
Subject: Re: less data lost, more fs corruption

Steve Lord [lord@xxxxxxx] wrote:

> > the first 6-8 test succeeded.
> > i cycled the tests without clean shutdowns between (hmmm maybe one
or two).
> > 
> > then i made only one sync. after reboot some files differ. same
> > size is ok, but no extents. the number of differs are small.
> Have you tried this with ext2?

no. shoud i?

> OK the real issue here is that sync is not really doing sync, the sync
> call is starting I/O, but not waiting for it to complete. At least two
> are probably necessary for this scenario right now. If you wait a few
> there will be a kernel initiated sync anyway. And as Ananth pointed
> there are some bits of I/O which will take a couple of passes to get
> Obviously we cannot immediately flush everything to disk or
> would tank. The issue with XFS in this area has always been that the
> inode size gets out to disk in advance of the file data. You are
> at a consistent filesystem, it just has data missing! This is why
> does not complain. 

ok, when the return of sync means "writing data to disk will done"
"writing data to disk is done" then the fix works.

btw: with 3 syncs and reset in less than a second lost data is seen.

is this on irix the same? sometimes i found those no extend files on
after a crash.


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