64K limit for VG/LV
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. 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.
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"?
Dieter.
Signature · 4 lines
Dieter St�ken, con terra GmbH, M�nster
[email protected] [email protected]
http://www.conterra.de/ http://qgp.uni-muenster.de/~stueken
(0)251-980-2027 (0)251-83-334974Quoted 24 lines · Dieter Stueken
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
Quoted 7 lines
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).
Quoted 2 lines
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.
Quoted 6 lines
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.
Quoted 13 lines
Dieter.
Signature · 10 lines
Dieter Stüken, con terra GmbH, Münster [email protected] [email protected] http://www.conterra.de/ http://qgp.uni-muenster.de/~stueken (0)251-980-2027 (0)251-83-334974 _______________________________________________ linux-lvm mailing list [email protected] http://lists.sistina.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html
Signature · 15 lines
Regards,
Heinz -- The LVM Guy --
*** Software bugs are stupid.
Nevertheless it needs not so stupid people to solve them ***
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Heinz Mauelshagen Sistina Software Inc.
Senior Consultant/Developer Am Sonnenhang 11
56242 Marienrachdorf
Germany
[email protected] +49 2626 141200
FAX 924446
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-Quoted 9 lines · Heinz J . Mauelshagen
that's correct. It is just a per LV limit for the max amount of its Logical Extents (LEs).
Quoted 2 lines
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.
but I still worry a bit about my data. The reason for the wrong "Free PE"
reported seems not to be the 64k limit, but the fact that some of my LVs are reported/counted twice!
-> vgdisplay -v vg0 | fgrep "LV Name"
LV Name /dev/vg0/root LV Name /dev/vg0/win2k LV Name /dev/vg0/ortho LV Name /dev/vg0/praktikum LV Name /dev/vg0/swap LV Name /dev/vg0/mirror LV Name /dev/vg0/disk_huetti LV Name /dev/vg0/SuSE-7.3 LV Name /dev/vg0/mirror <<<<< LV Name /dev/vg0/disk_huetti <<<<<
Thus I still fear of some evil inconsistencies for my data. Is there any tool available like "e2fsck" for LVM to resolve such a problem?
Dieter.