[linux-lvm] diff. in striping between HP-UX and Linux LVM
Stephan Hendl
Stephan.Hendl at lds.brandenburg.de
Fri Sep 14 06:08:22 UTC 2001
Hi all,
I have to work with both systems an found some differences in the striping between the two kinds of LVM. I created a vg consisting of two disks on the HP-UX and on the linux system and a lv with the "-i 2 -I 64"-option.
In the case of HP-UX the first LE points to the first PE on the first disk, the second LE points to the first PE of the second disk and so on.
In case of Linux LVM the LEs corrospond to the PEs, there is no alternation and therefore no enhancement of performance because only one disk will be used at the same time.
Where I am wrong?
ciao
Stephan
HP-UX:
--- Logical volumes ---
LV Name /dev/vgmail/lvol1
VG Name /dev/vgmail
LV Permission read/write
LV Status available/syncd
Mirror copies 0
Consistency Recovery MWC
Schedule striped
LV Size (Mbytes) 4096
Current LE 1024
Allocated PE 1024
Stripes 2
Stripe Size (Kbytes) 64
Bad block NONE
Allocation strict
IO Timeout (Seconds) default
--- Distribution of logical volume ---
PV Name LE on PV PE on PV
/dev/dsk/c4t6d1 512 512
/dev/dsk/c6t6d2 512 512
--- Logical extents ---
LE PV1 PE1 Status 1
00000 /dev/dsk/c4t6d1 00000 current
00001 /dev/dsk/c6t6d2 00000 current
00002 /dev/dsk/c4t6d1 00001 current
00003 /dev/dsk/c6t6d2 00001 current
00004 /dev/dsk/c4t6d1 00002 current
00005 /dev/dsk/c6t6d2 00002 current
00006 /dev/dsk/c4t6d1 00003 current
00007 /dev/dsk/c6t6d2 00003 current
...
Linux:
--- Logical volume ---
LV Name /dev/vg00/lvol1
VG Name vg00
LV Write Access read/write
LV Status available
LV # 1
# open 1
LV Size 4 GB
Current LE 1024
Allocated LE 1024
Stripes 2
Stripe size (KByte) 64
Allocation next free
Read ahead sectors 120
Block device 58:0
--- Distribution of logical volume on 2 physical volumes ---
PV Name PE on PV reads writes
/dev/sdb1 512 1536487 1472056
/dev/sdc1 512 1535960 1472315
--- logical volume i/o statistic ---
3072447 reads 2944371 writes
--- Logical extents ---
LE PV PE reads writes
00000 /dev/sdb1 00000 0 1008
00001 /dev/sdb1 00001 0 1024
00002 /dev/sdb1 00002 0 590
00003 /dev/sdb1 00003 0 848
00004 /dev/sdb1 00004 0 16
00005 /dev/sdb1 00005 0 0
00006 /dev/sdb1 00006 272 2594
--
LDS Brandenburg
Dr. Stephan Hendl
fon: +49-(0)331-39 471
fax: +49-(0)331-27548 1187
EMail: stephan.hendl at lds.brandenburg.de
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