[linux-lvm] Re: Parallel mirroring

[Diego Jacobi]

Hi.

Sry for retry but the lvm list is my last resource.

Does Linux-LVM have Parallel scheduler mode for mirroring at all?
If yes, how do you set it up, or check if it is enabled?

Thanks.
Diego



2009/7/12 Diego Jacobi <jacobidiego at gmail.com>:
> Hello.
>
> I have succesfully configured Mirroring between 2 disks in linux for 2
> logical volumes, and on other without mirroring.
> But i can not find any evidence showing that it is reading in parallel
> scheduler mode.
> I have read HP docs about HP-UX, but it talks about command line
> options which arent in the linux side.
>
> The "-d p" in HP-UX would be what i need now for linux. Also lvdisplay
> doesnt show anything about it, more than the number of mirrors.
>
>
> This are my tests:
>
> sda1 = /boot in disk 1, no lvm
> sdb1 = /boot in disk 2, no lvm
> data/data = lvm without mirroring
> data/root = lvm with mirroring
>
>
> linux-8mmd:~ # hdparm -t /dev/sda1
> /dev/sda1:
>  Timing buffered disk reads:  262 MB in  3.02 seconds =  86.83 MB/sec
>
> linux-8mmd:~ # hdparm -t /dev/sdb1
> /dev/sdb1:
>  Timing buffered disk reads:  174 MB in  3.03 seconds =  57.36 MB/sec
>
> linux-8mmd:~ # hdparm -t /dev/data/data
> /dev/data/data:
>  Timing buffered disk reads:  272 MB in  3.02 seconds =  90.02 MB/sec
>
> linux-8mmd:~ # hdparm -t /dev/data/root
> /dev/data/root:
>  Timing buffered disk reads:  278 MB in  3.02 seconds =  92.16 MB/sec
>
>
>
> As you can see, the read speed are mostly the same. This could mean a
> secuenced scheduler.
>
> And this is my system setup:
>
> lvm> version
>  LVM version:     2.02.39 (2008-06-27)
>  Library version: 1.02.27 (2008-06-25)
>  Driver version:  4.14.0
>
> linux-8mmd:~ # pvs
>  PV         VG   Fmt  Attr PSize   PFree
>  /dev/sda3  data lvm2 a-   537.11G 395.12G
>  /dev/sda5  data lvm2 a-   996.00M 988.00M         <--- Note 1 Gb, for log
>  /dev/sdb3  data lvm2 a-   138.99G 118.99G
>
> linux-8mmd:~ # lvs -a -o +devices
>  LV              VG   Attr   LSize   Origin Snap%  Move Log
> Copy%  Convert Devices
>  data            data -wi-ao 121.50G
>           /dev/sda3(125)
>  home            data mwi-ao  10.00G                    home_mlog
> 100.00         home_mimage_0(0),home_mimage_1(0)
>  [home_mimage_0] data iwi-ao  10.00G
>           /dev/sda3(33788)
>  [home_mimage_1] data iwi-ao  10.00G
>           /dev/sdb3(2560)
>  [home_mlog]     data lwi-ao   4.00M
>           /dev/sda5(1)
>  root            data mwi-ao  10.00G                    root_mlog
> 100.00         root_mimage_0(0),root_mimage_1(0)
>  [root_mimage_0] data iwi-ao  10.00G
>           /dev/sda3(31228)
>  [root_mimage_1] data iwi-ao  10.00G
>           /dev/sdb3(0)
>  [root_mlog]     data lwi-ao   4.00M
>           /dev/sda5(0)
>  test            data -wi-a- 500.00M
>           /dev/sda3(0)
>