cache buffer size
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.
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
Quoted 6 lines · Miwako Nakai
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 --
Quoted 12 lines
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
Quoted 8 lines
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read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
*** Software bugs are stupid.
Nevertheless it needs not so stupid people to solve them ***
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Heinz Mauelshagen Sistina Software Inc.
Senior Consultant/Developer Am Sonnenhang 11
56242 Marienrachdorf Germany
[email protected] +49 2626 141200
FAX 924446
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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.
Quoted 37 lines · Heinz J . Mauelshagen
Quoted 6 lines · Miwako Nakai
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 --Quoted 8 lines
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.Quoted 6 lines
kernel 2.4.20-pre10-ac2
lvm 1.0.5
jfs 1.0.23*** Software bugs are stupid.
Nevertheless it needs not so stupid people to solve them ***=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Quoted 7 lines
Heinz Mauelshagen Sistina Software Inc.
Senior Consultant/Developer Am Sonnenhang 11
56242 Marienrachdorf Germany
[email protected] +49 2626 141200FAX 924446=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Quoted 5 lines · Miwako Nakai
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'.
Didn't know that as a JFS no-user :)
Fixed block sizes is a suboptimal solution for the various io needs of a filesystem (think small metedata and large data io).
If they do io with varying blocksizes, that would explain the MD RAID5 behaviour already. No way to avoid it in your combination for now then I guess.
Quoted 3 lines
I think LVM(2?) will be able to handle non-consitant block size on 2.5 well.
Yes.
Regards,
Heinz -- The LVM Guy --
Quoted 33 lines
Quoted 9 lines · Heinz J . Mauelshagen
Quoted 6 lines · Miwako Nakai
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.Quoted 22 lines
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 --Quoted 14 lines
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
Quoted 8 lines
_______________________________________________
linux-lvm mailing list
[email protected]
http://lists.sistina.com/mailman/listinfo/linux-lvm
read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
*** 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
[email protected] +49 2626 141200
FAX 924446
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-