[linux-lvm] 64K limit for VG/LV
Heinz J . Mauelshagen
mauelshagen at sistina.com
Tue Jan 22 12:44:02 UTC 2002
On Tue, Jan 22, 2002 at 01:57:51PM +0100, Dieter Stueken wrote:
> I just merged two volume groups without any error message,
> but the result seems to have more than 65535 LE now. The only
> effect until now is, that the number of free PE becomes negative
> and is displayed as an unsigned huge value:
>
> --- Volume group ---
> VG Name vg0
> VG Access read/write
> VG Status available/resizable
> VG # 0
> MAX LV 256
> Cur LV 9
> Open LV 2
> MAX LV Size 255.99 GB
> Max PV 256
> Cur PV 4
> Act PV 4
> VG Size 286.33 GB
> PE Size 4.00 MB
> Total PE 73300
> Alloc PE / Size 97200 / 379.69 GB
> Free PE / Size 4294943396 / 1.91 TB
> VG UUID QDKBpV-xwqr-gO3b-VKiA-Jaf4-grmm-pWEY32
>
> My VG consists of 4 x 75 GB IBM-DTLA-307075. Should I worry now?
> If there is any limit of 65536 I might suspect some 16bit value
> for PE addressing. If no overflow is checked, a wrong PE may be
> addressed beyond LE 65536 and my VG possibly gets destroyed :-(
>
> But I found some hints in the mailing archive, saying that the
> 64K limit does not affect the VG itself but only each LV inside.
Dieter,
that's correct. It is just a per LV limit for the max amount of its
Logical Extents (LEs).
> Thus as long as each of my LV is <256G I don't have to worry, and
> the reported "Free PE" might be just cosmetics.
Cosmetics is a nice way to put it :-)
We probably have missed that one, because for a VG with such a large capacity
we choosed larger PE sizes.
>
> Besides, vgdisplay says: "Logical Volume Manager 1.0.1-rc2"
> On SuSE 7.3 running 2.4.16.
>
> If I want to increase my LE size, I think I have to create a new VG.
> Is there any tool to copy my LVs to the new VG other than "dd"?
cat ;-)
No, sorry. None included in LVM.
>
> Dieter.
> --
> Dieter Stüken, con terra GmbH, Münster
> stueken at conterra.de stueken at qgp.uni-muenster.de
> http://www.conterra.de/ http://qgp.uni-muenster.de/~stueken
> (0)251-980-2027 (0)251-83-334974
>
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--
Regards,
Heinz -- The LVM Guy --
*** Software bugs are stupid.
Nevertheless it needs not so stupid people to solve them ***
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Heinz Mauelshagen Sistina Software Inc.
Senior Consultant/Developer Am Sonnenhang 11
56242 Marienrachdorf
Germany
Mauelshagen at Sistina.com +49 2626 141200
FAX 924446
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