From: pSeries AIX Geek (aixgeek@YAHOO.COM)
Date: Tue Oct 08 2002 - 01:20:38 EDT
You could also set your LV to maximum allocation, the
number of PPs to two, and try running reorgvg to split
the LV across the two disks:
chlv -e x -u 2 my_lv
reorgvg my_vg my_lv
- pAG
--- Holger.VanKoll@SWISSCOM.COM wrote:
> Hello,
>
> I got a fs (say) called my_fs on lv my_lv thats on
> hdisk2, 20 LPs, no
> mirroring.
>
> hdisk2 is overloaded, especially with this fs. So I
> want to migrate 10
> of the 20 LPs to another disk.
>
> hdisk3 and hdisk4 are in the same vg, both have 11
> LP free. hdisk4 has
> also much load, so I only want to "stripe" my_fs on
> hdisk2 and hdisk3.
>
> I cant use migratepv -l my_lv, it always migrates
> the whole lv.
>
> I could use chlv to set intrapolicy to max and do an
> reorgvg. That
> however would distribute my_lv on hdisk2 and hdisk3
> and hdisk4.
> To prevent this, I could use "chpv -a n hdisk4" to
> prevent further
> pp-allocations to hdisk4.
> That could work, but did anyone ever do this? I am
> worrying about
> performance. reorgvg needs one free pp (man
> reorgvg). Does that mean it
> will temporarily mirror every pp on this free pp (11
> LP free - 10 PP to
> get allocated) ?
>
> I could also use mklvcopy to make a lv copy on
> hdisk4. Then remove the
> "original" copy on hdisk2. Then mklvcopy -m
> map_file_containing_hdisk2_and_hdisk3 and rmlvcopy
> my_lv hdisk4. That
> should also work, however, then the whole lv will be
> copied twice. And
> all I need to do is moving some PP from hdisk2 to
> hdisk3...
>
> Actually there are much more LP to be moved than 10.
> I just took this
> small number for explanation. There are 220 PPs at
> 256MB size to be
> moved; and I must avoid any unnecessary IO.
>
> Do you have any other ideas to move half of an lv to
> another disk?
> Or did you every try one of my "ideas"?
>
> I looked through the scripts reorgvg and migratepv
> and I think the key
> to the solution with fewest IO (so, no unnecessary
> IO) is lmigratepp or
> lmigratelv. Is there any detailed documentation
> about these commands
> (beside lvm commands redbook)? I cant find out
> whether the mapfile
> parameter of lmigratelv accepts mapfile with entries
> that (partly)
> reflect the current allocation of the lv.
>
> I know all this is a poor-mans-stripe, but currently
> I cant create a
> striped lv and copy ms_fs to it; lack of space and
> lack of possible
> downtime (umount my_fs).
>
> Regards,
>
> Holger
>
>
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