Leland Lucius already pointed out how to work around this ("lvextend -I 1").
Tom may not have seen that as an option because he used YaST. You have to
run the component parts (lvextend and ext2online) by hand to change the
striping. (You may also have to do that to get a helpful error message;
my memory is that YaST failed saying no space, which was really confusing
when we could see free cylinders in the volume group.)
Ted Rodriguez-Bell
Wells Fargo, Mainframe and Midrange Services
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-----Original Message-----
From: Duerbusch, Tom [mailto:[email protected]]
Sent: Wednesday, October 10, 2012 11:37 AM
Subject: Re: HyperPAV and LVM striping
So that might have been my problem (but not necessarily limited to that
one).
I was on Suse 10 system. I initially stripped the LVM. When it got nearly
full, I tried to add a pack. Couldn't do it. So I went back and recreated
the LVM without striping and I could add a pack. I want to say that the
documentation at that time, also said you couldn't add packs to a striped
LVM, but that was a while ago.
Anyway, it hasn't been a performance issue. But that is due to us not
needing the I/O performance.
Thanks for the update. I'm updating my notes.
Tom Duerbusch
THD Consulting
On Wed, Oct 10, 2012 at 12:53 PM, Mark Post <[email protected]> wrote:
> >>> On 10/10/2012 at 11:35 AM, "Duerbusch, Tom" <[email protected]>
> wrote:
>
> > Just speaking to LVM...
> >
> > Striping the data across multiple volumes (which in modern dasd is
> already
> > stripped in the Raid array), would give you the best performance.
> > Especially if you can strip across multiple DS8000 (or other dasd
> > subsystems).
> >
> > But you can also use LVM as a pool of DASD, with no striping involved.
> >
> > In case 1, if you need to expand the LVM pool, it is a hassle. It might
> > mean backing up, reformatting and reloading the data. In any case, it
> > involves a knowledgeable person and most likely, downtime.
>
> This is simply not true. Expanding a striped LV can be done dynamically
> with no downtime. The only aspect that is different from a non-striped LV
> is that you have to have enough free space on as many different PVs as the
> number of stripes you have. That is, if you did an "lvcreate -i 2" then
> when you do an lvextend/lvresize, you have to have free space available on
> 2 different PVs in the pool. An "lvcreate -i 3" means you need free space
> on 3 PVs, etc.
>
> A lot of people tend to add space to a volume group one PV at a time. If
> you're using striped LVs, that won't work unless you make sure that the
> existing PVs have enough free space on them to accommodate additional
> stripes being allocated.
>
>
> Mark Post
>
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