On 22/04/2009 10:16, Goswin von Brederlow wrote:
John Robinson <john.robinson@xxxxxxxxxxxxxxxx> writes:
Can't do that, my root filesystem is on the RAID-5, and part of the
reason for wanting the bitmap is because the md can't be stopped while
shutting down, so it was always wanting to resync at startup, which is
rather tedious.
Normal shutdown should put the raid in read-only mode as last step. At
least Debian does that. That way even a mounted raid will be clean
after reboot.
Yes, I would have thought it should as well. But I've just looked at
CentOS 5's /etc/rc.d/halt and as far as I can see it doesn't try to
switch md devices to read-only. Of course the root filesystem has gone
read-only but as we know that doesn't mean the device underneath it gets
told that. In particular we know that ext3 normally opens its device
read-write even when you're mounting the filesystem read-only (iirc it's
so it can replay the journal).
Another issue might be the LVM layer; does that need to be stopped or
switched to read-only too?
I would also suggest restructuring your system like this:
sdX1 1GB raid1 / (+/boot)
sdX2 rest raid5 lvm with /usr, /var, /home, ...
Both / and /usr can usualy be read-only preventing any filesystem
corruption and raid resyncs in that part of the raid.
I did do this multiple partition/LV thing once upon a time, but I got
fed up with having to resize things when one partition was full and
others empty. The machine is primarily a fileserver and Xen host, so the
dom0 only has 40GB of its own, and I couldn't be bothered splitting that
up. Having said all this, your suggestion is a good one, it's just my
preference to have it otherwise :-)
Cheers,
John.
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