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From: "Vladimir V. Saveliev" <vs@namesys.com>
To: Andrew Morton <akpm@osdl.org>
Cc: sander@humilis.net, neilb@cse.unsw.edu.au,
	linux-kernel@vger.kernel.org, reiserfs-dev@namesys.com
Subject: Re: segfault mdadm --write-behind, 2.6.14-mm2
Date: Fri, 18 Nov 2005 17:18:39 +0300	[thread overview]
Message-ID: <437DE2BF.8010008@namesys.com> (raw)
In-Reply-To: <20051116142000.5c63449f.akpm@osdl.org>

Hello

Andrew Morton wrote:
> Sander <sander@humilis.net> wrote:
>>Neil Brown wrote (ao):
>>> If you use mdadm-2.0 and mark a device as --write-mostly, then all
>>> read requests will go to the other device(s) if possible,.
>>> e.g.
>>>   mdadm --create /dev/md0 --level=1 --raid-disks=2 /dev/ramdisk \
>>>      --writemostly /dev/realdisk
>>>
>>> Does this suit your needs?
>>>
>>> You can also arrange for the write to the writemostly device to be
>>> 'write-behind' so that the filesystem doesn't wait for the write to
>>> complete.  This can reduce write-latency (though not increase write
>>> throughput) at a very small cost of reliability (if the RAM dies, the
>>> disk may not be 100% up-to-date).
>>With 2.6.14-mm2 (x86) and mdadm 2.1 I get a Segmentation fault when I
>>try this:
> 
> It oopsed in reiser4.  reiserfs-dev added to Cc...
> 
>>mdadm -C /dev/md1 -l1 -n2 --bitmap=/storage/md1.bitmap /dev/loop0 \
>>--write-behind /dev/loop1
>>
>>loop0 is attached to a file on tmpfs, and loop1 is attached
>>to a file on a lvm2 volume (reiser4, if that matters).
>>

I tried ext2 on lvm2 and that did not help.
So, for now I would assume that the problem is not in reiser4 but somewhere else.


      parent reply	other threads:[~2005-11-18 14:18 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-09-05  0:46 RAID1 ramdisk patch Wilco Baan Hofman
2005-09-05  1:27 ` Neil Brown
2005-09-05  7:40   ` Wilco Baan Hofman
2005-11-16 13:36   ` segfault mdadm --write-behind, 2.6.14-mm2 (was: Re: RAID1 ramdisk patch) Sander
2005-11-16 22:20     ` Andrew Morton
2005-11-16 23:08       ` Neil Brown
2005-11-17  7:50         ` Sander
2005-11-17 10:12           ` Sander
2005-11-17 10:15             ` Sander
2005-11-21 23:07               ` Please help me understand ->writepage. Was " Neil Brown
2005-11-21 23:30                 ` Jeff Garzik
2005-11-21 23:51                 ` Andrew Morton
2005-11-22  3:12                   ` Neil Brown
2005-11-22  3:47                     ` Andrew Morton
2005-11-22 10:34                     ` Sander
2005-11-24  5:41                       ` Please help me understand reiser4_writepage. " Neil Brown
2005-11-22 12:00                     ` Please help me understand ->writepage. " Anton Altaparmakov
2005-11-24  5:29                       ` Neil Brown
2005-11-18 14:18       ` Vladimir V. Saveliev [this message]

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