[Xen-users] IO is a big difference between the "file" and "phy"

[ÐÑÑÐÐÐ ÐÐÑÐÐÐÐ <ufaweb@xxxxxxxxx>]

Hello

in dom0:

root@nas-1:/etc/xen# cat /etc/xen/mogilefs-images.nas-1.lo.ufanet.ru.cfg
...
disk        = [

'file:/home/xen/domains/mogilefs-images.nas-1.lo.ufanet.ru/disk.img,xvda2,w',

'file:/home/xen/domains/mogilefs-images.nas-1.lo.ufanet.ru/swap.img,xvda1,w',
                  'phy:/dev/nas-1/mogilefs-images,xvdb1,w',
                  'file:/mnt/ext4,xvdb2,w',
              ]
...

Here, /dev/nas-1/mogilefs-images is logical volume in LVM, /mnt/ext4
is file located on the other logical volume in the same LVM.
LVM is one volume group located on one physical volume (software raid6
- 12 hdd).


in domU (mogilefs-images.nas-1.lo.ufanet.ru):
root@mogilefs-images:~# mount /dev/xvdb1 /mnt/lvm
root@mogilefs-images:~# mount /dev/xvdb2 /mnt/file
root@mogilefs-images:~# dd if=/dev/zero of=/mnt/lvm/test.file bs=40960
count=50000
50000+0 records in
50000+0 records out
2048000000 bytes (2.0 GB) copied, 71.1815 s, 28.8 MB/s
root@mogilefs-images:~# dd if=/dev/zero of=/mnt/file/test.file
bs=40960 count=50000
50000+0 records in
50000+0 records out
2048000000 bytes (2.0 GB) copied, 17.3065 s, 118 MB/s

Why such a big difference in the rate of io (is physically on the same device)?

-- 
Ð ÑÐÐÐÐÐÐÐÐ, ÐÐÑÐÐÐÐ ÐÑÑÐÐÐ.
ÐÑÐÐÐÐÐÐÑÐÐÑ ÐÑÐÐÐÐ ÑÐÐÑÐÐÐÑÐÐ Ð ÑÐÐÑÐÐÐÐÐÐÐÐÑ ÐÑÐÐÑÐÐÐÐÐÐÐ
ÐÐÐÑÐÐÑÐÐÐÑ ÐÐÐ "ÐÑÐÐÐÑ".

ÐÐÐÑÐÐÑÐÐÑ ÐÐÑÐÑÐÐÑÐÑ:
google+: http://gplus.to/ruslan
jid: serafim@xxxxxxxxxxxxxxxx
wave: ufaweb@xxxxxxxxxxxxxx
skype: ufaweb
phone: +7(917)4775460
vkontakte: http://vkontakte.ru/ufaweb
myspace: http://www.myspace.com/ufaweb
facebook: http://facebook.com/sharipov
linkedin: http://www.linkedin.com/in/ufaweb
twitter: http://twitter.com/ufaweb

_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxx
http://lists.xen.org/xen-users