Yeah, multi-striped LVM volumes are 'interesting'. You CAN do a lvextend on
multi-striped logical volumes, but it will fail unless you have the same
number of blocks available on each PV that the striped LV resides on.
Unfortunately, when most people create a striped LV, they make it as large
as possible, so there are no free blocks left on the underlying PVs. Thes
means that your LV will now behave like a RAID0 array; you'll have to
destroy it to make it larger.
Hrm, I wonder if EVMS will resolve this? Or LVM2?
Jay Brenneman
Mark Perry
<mark.perry@high-plough-co To:
[EMAIL PROTECTED]
mputers.de> cc:
Sent by: Linux on 390 Port Subject: Re: FW: striped LVM
non-extensible
<[EMAIL PROTECTED]>
10/22/2002 06:02 PM
Please respond to
mark.perry
Hi Ken,
5 stripes = 5 volumes (PVs) that's it no more to say :-(
One solution, if you are using 3390-3 currently, is to add 5 by 3390-9 (or
mod 27) to the VG using pvcreate and vgextend, then use pvmove to move each
3390-3 PV to a new 3390-9 PV. Once complete you could, if you wish, use
vgreduce to eliminate the 3390-3 from the VG. Then use lvextend to expand
the LV by a factor of 3 (or 9 for mod 27).
Now I venture into the unknown......
I wonder if it is possible using md (raidtab mkraid) to create 5 seperate
md
devices (each a set of raid spanning 3390s) and then create a PV out of
each
of these and then add them as per my suggestion for 3390-9 above. In effect
you would get your wish for a very large set of 5 PVs.
Hey - I know its way out there but I'm just trying to help ;-)
Ciao
Mark
-----Original Message-----
From: Linux on 390 Port [mailto:LINUX-390@;VM.MARIST.EDU]On Behalf Of
Hall, Ken (ECSS)
Sent: 21 October 2002 22:42
To: [EMAIL PROTECTED]
Subject: Re: FW: striped LVM non-extensible
I work with Phil, and I'm the one who was actually trying to do this.
The VG consisted of 5 physical volumes, with one LV, 5 stripes. I added an
additional volume, but couldn't extend (insufficient physical extents).
After some research, it appeared it might work if I
added a total of 5 physical volumes (same as the number of stripes), but
that also failed.
In the end, I backed up the whole LV, and rebuilt it, but in the process
had
to make it MUCH bigger (28 volumes). At that point, I couldn't get
striping
to work at ALL, and finally went with an
unstriped volume.
I believe there's just something I don't understand about the LVM and
striping, but haven't found any explanation. Can anyone shed some light on
this?
> -----Original Message-----
> From: Heinz J . Mauelshagen [mailto:Heinz.Mauelshagen@;T-ONLINE.DE]
> Sent: Friday, October 18, 2002 10:11 AM
> To: [EMAIL PROTECTED]
> Subject: Re: [LINUX-390] FW: striped LVM non-extensible
>
>
> On Thu, Oct 17, 2002 at 08:18:18AM -0500, Montgomery Mouw wrote:
> > Heinz,
> >
> > Do you have any insight on this question? Thanks.
> >
> > Mo
> >
> > > -----Original Message-----
> > > From: Linux on 390 Port
> [mailto:LINUX-390@;VM.MARIST.EDU]On Behalf Of
> > > Phil Tully
> > > Sent: Thursday, October 17, 2002 7:25 AM
> > > To: [EMAIL PROTECTED]
> > > Subject: striped LVM non-extensible
> > >
> > >
> > > We have moved a large filesystem to a striped LVM (5
> physical volumes, 5
> > > stripes) and now find that one of the advantages of LVM is lost,
> > > non-disruptive expansion. I wanted to make sure I am
> correct that a
> > > striped LVM can not be expaned without being rebuild?
>
> Phil,
>
> a constraint with LVM1 is that stripes can't be extended beyond
> physical volumes :-(
>
> FYI: that constraint won't exist in LVM2 any longer. LVM2 is or new
> GPLed code base which will go GA in December and is
> avaolable on Linux
> 2.4 _and_ 2.5 already.
>
> LVM2 is fully metadata compatible with LVM1 so that in-place upgrades
> _without_ any nasty backup/reconfigure/restore cycles are supported.
>
>
> I see 3 options for you now:
>
> - if you have free or can free enough extents of other LVs on
> your 5 PVs -> use
> pvmove to achieve that and extend your stripes on the given PVs
>
> - if you can add 5 larger PVs to the VG holding the striped LV ->
> use pvmove to move the stripes to the bigger PVs and extend
> the striped LV
> afterwards
>
> - if LVM2 is an option for you and you can wait for GA ->
> that's the way to
> go to extend your striped LV because (as mentioned above)
> stripes can span
> multiple PVs in LVM2
>
> > >
> > > Phil
> > >
> > >
>
> Regards,
> Heinz -- The LVM Guy --
>
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> =-=-=-=-=-=-=-=-
>
> Heinz Mauelshagen Sistina
> Software Inc.
> Senior Consultant/Developer Am Sonnenhang 11
> 56242 Marienrachdorf
> Germany
> [EMAIL PROTECTED] +49 2626 141200
> FAX 924446
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> =-=-=-=-=-=-=-=-
>
