* [linux-lvm] diff. in striping between HP-UX and Linux LVM
@ 2001-09-14 6:08 Stephan Hendl
2001-09-14 8:00 ` Heinz J . Mauelshagen
0 siblings, 1 reply; 2+ messages in thread
From: Stephan Hendl @ 2001-09-14 6:08 UTC (permalink / raw)
To: <
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@lds.brandenburg.de
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [linux-lvm] diff. in striping between HP-UX and Linux LVM
2001-09-14 6:08 [linux-lvm] diff. in striping between HP-UX and Linux LVM Stephan Hendl
@ 2001-09-14 8:00 ` Heinz J . Mauelshagen
0 siblings, 0 replies; 2+ messages in thread
From: Heinz J . Mauelshagen @ 2001-09-14 8:00 UTC (permalink / raw)
To: linux-lvm
Stephan,
the alternation of the subalocated stripes isn't visible in "lvdisplay -v".
In principle the allocation looks like (assuming an exmaple LV with
3 stripes and 6 LE):
LE0 -> PEa on PV1
LE1 -> PEb on PV1
LE2 -> PEc on PV2
LE3 -> PEd on PV2
LE4 -> PEe on PV3
LE5 -> PEf on PV3
If the stripes have a size of 64K the accesses to the address space of
the LV go like:
1st 64k -> 1st 64K PEa
2nd 64k -> 1st 64K PEc
3rd 64k -> 1st 64K PEe
4th 64k -> 2nd 64K PEa
5th 64k -> 2nd 64K PEc
6th 64k -> 2nd 64K PEe
...
Regards,
Heinz -- The LVM Guy --
On Fri, Sep 14, 2001 at 08:08:22AM +0200, Stephan Hendl wrote:
> 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@lds.brandenburg.de
>
>
>
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@sistina.com
> http://lists.sistina.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html
*** 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
Mauelshagen@Sistina.com +49 2626 141200
FAX 924446
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
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