On 06/09/10 18:23, Kirby Zhou wrote:
Does LVM-LV take system cache?
In my test, it does not take system cache on a RHEL5 box, is it a bug or
a feature?
Test1, run dd with raw block device, it seems system cache can boost up
reread operation.
[...@djt_18_69 ~]# dd if=/dev/sdc bs=1M of=/dev/null count=500
524288000 bytes (524 MB) copied, 1.88267 seconds, 278 MB/s
[...@djt_18_69 ~]# dd if=/dev/sdc bs=1M of=/dev/null count=500
524288000 bytes (524 MB) copied, 0.13445 seconds, 3.9 GB/s
Test2, run dd with lv, it seems system cache CAN NOT boost up reread
operation.
[...@djt_18_69 ~]# dd if=/dev/vgext/lvtest5 bs=1M of=/dev/null count=500
524288000 bytes (524 MB) copied, 2.17848 seconds, 241 MB/s
[...@djt_18_69 ~]# dd if=/dev/vgext/lvtest5 bs=1M of=/dev/null count=500
524288000 bytes (524 MB) copied, 2.17451 seconds, 241 MB/s
Both 2.6.18-164.15.1.el5 and 2.6.18-194.el5 do the same behavior.
Regards
Kirby Zhou
and with a file on a filesystem?
_______________________________________________
rhelv5-list mailing list
[email protected]
https://www.redhat.com/mailman/listinfo/rhelv5-list
