Re: [linux-lvm] cache buffer size

[Miwako Nakai <nickey@be.mbn.or.jp>]

Thank you, Mr.Mauelshagen

JFS can not have fixed block size. But I heard from JFS group in IBM
that on 2.5 or later it will be improved. I do not know JFS will have
fixed block size or not. They said 'improved'.

I think LVM(2?) will be able to handle non-consitant block size on
2.5 well.

"Heinz J . Mauelshagen" wrote:
> 
> On Fri, Nov 01, 2002 at 12:07:40PM +0900, Miwako Nakai wrote:
> > I'm using jfs on lvm/raid5 with snapshot.
> >
> > When I copy file, it happens frequently
> > 'raid5: switching cache buffer size XXX -> XXX'.
> > This message appears to syslog. It caused speed down to access disks.
> > So, I cut this message. It's seemed ok.
> 
> Could be filesystems with different blocksizes accessing the underlying
> raid5 md through LVM constantly forcing the raid5 stripe cache to be flushed.
> If that's the case, you want to put filesystems of the _same_ blocksize
> onto all of the logical volumes allocated to the raid5 device.
> 
> Regards,
> Heinz    -- The LVM Guy --
> 
> >
> > But it's still going to switch cache buffer size. I think it cost
> > some cpu time. When switching buffer cache size, it always happen
> > reflushing memories.
> >
> > I want to fix buffer size. What shall I do?
> > I asked JFS group. But they do nothing about cache buffer.
> >
> > kernel 2.4.20-pre10-ac2
> > lvm    1.0.5
> > jfs    1.0.23
> >
> > --
> > nakai@ezinc.com
> 
> *** Software bugs are stupid.
>     Nevertheless it needs not so stupid people to solve them ***
> 
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> 
> Heinz Mauelshagen                                 Sistina Software Inc.
> Senior Consultant/Developer                       Am Sonnenhang 11
>                                                   56242 Marienrachdorf
>                                                   Germany
> Mauelshagen@Sistina.com                           +49 2626 141200
>                                                        FAX 924446
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

--
nakai@ezinc.com