In my log files, which go back to Dec 12
I have 4 of these:
raid5: switching cache buffer size, 4096 --> 1024
And 2 of these:
raid5: switching cache buffer size, 1024 --> 4096
So, it would concern me! The message is from RAID5, not LVM. I base this
on "raid5:" in the log entry. :)
Guy
I found this from Neil:
"You will probably also see a message in the kernel logs like:
raid5: switching cache buffer size, 4096 --> 1024
The raid5 stripe cache must match the request size used by any client.
It is PAGE_SIZE at start up, but changes whenever is sees a request of a
difference size.
Reading from /dev/mdX uses a request size of 1K.
Most filesystems use a request size of 4k.
So, when you do the 'dd', the cache size changes and you get a small
performance drop because of this.
If you make a filesystem on the array and then mount it, it will probably
switch back to 4k requests and resync should speed up.
NeilBrown"
-----Original Message-----
From: linux-raid-owner@xxxxxxxxxxxxxxx
[mailto:linux-raid-owner@xxxxxxxxxxxxxxx] On Behalf Of maarten
Sent: Monday, January 10, 2005 11:34 AM
To: linux-raid@xxxxxxxxxxxxxxx
Subject: Re: Spares and partitioning huge disks
On Saturday 08 January 2005 20:01, maarten wrote:
> On Saturday 08 January 2005 17:49, maarten wrote:
> > On Saturday 08 January 2005 15:52, Frank van Maarseveen wrote:
> > > On Fri, Jan 07, 2005 at 04:57:35PM -0500, Guy wrote:
> As the system is now online again, busy copying, I can show the exact
> config:
>
Well all about the array is done and working fine up to now. Except one
thing
that I didn't anticipate: The application that's supposed to run has some
problems under -I suppose- the new 2.4.28 kernel. I've had two panics /
oopses in syslog already, and the process then is unkillable, so a reboot is
in order. But I think that's bttv related, not the I/O layer.
In any case I suffered through two lengthy raid resyncs already... ;-|
So I've been shopping around for a *big* servercase today so I can put all
disks (these 5, plus 6 from the current fileserver) in one big tower. I'll
then use that over NFS and can revert back to my older working kernel.
I've chosen a Chieftec case, as can be seen here
http://www.chieftec.com/products/Workcolor/CA-01.htm
and here in detail
http://www.chieftec.com/products/Workcolor/NewBA.htm
Nice drive cages, eh ? :-)
P.S.: I get this filling up my logs. Should I be worried about that ?
Jan 10 11:30:32 dozer kernel: raid5: switching cache buffer size, 512 -->
4096
Jan 10 11:30:33 dozer kernel: raid5: switching cache buffer size, 4096 -->
512
Jan 10 11:30:33 dozer kernel: raid5: switching cache buffer size, 512 -->
4096
Jan 10 11:30:36 dozer kernel: raid5: switching cache buffer size, 4096 -->
512
Maarten
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