|
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 |
_______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
