[linux-lvm] How do you create large numbers of LVs? (In the 1000s) Is it even possible?
Ming Zhang
mingz at ele.uri.edu
Thu Jul 28 21:26:31 UTC 2005
I did vgchange -an vg1
and then still fail
[root at fc3-i386-2 ~]# lvcreate -L12M -ntv282 vg1
VG vg1 metadata writing failed
[root at fc3-i386-2 ~]# lvcreate -vvvvv -L12M -ntv282 vg1
Setting global/locking_type to 1
Setting global/locking_dir to /var/lock/lvm
File-based locking enabled.
Getting target version for linear
dm version
dm versions
Getting target version for striped
dm versions
Locking /var/lock/lvm/V_vg1 WB
Finding volume group "vg1"
Opened /dev/sda
/dev/sda: No label detected
Opened /dev/md0
/dev/md0: Failed to read label area
Opened /dev/sda1
/dev/sda1: No label detected
Opened /dev/sda2
/dev/sda2: No label detected
Opened /dev/sda3
/dev/sda3: No label detected
Opened /dev/sdb
/dev/sdb: No label detected
Opened /dev/sdb1
/dev/sdb1: lvm2 label detected
/dev/sdb1: lvm2 label detected
Read vg1 metadata (710) from /dev/sdb1 at 50688 size 65377
Creating logical volume tv282
Allowing allocation on /dev/sdb1 start PE 843 length 180
Archiving volume group "vg1" metadata.
VG vg1 metadata writing failed
Unlocking /var/lock/lvm/V_vg1
Closed /dev/sda
Closed /dev/md0
Closed /dev/sda1
Closed /dev/sda2
Closed /dev/sda3
Closed /dev/sdb
Closed /dev/sdb1
i use this script to create them
#!/bin/bash
# a simple loop to create large # of LV
LIMIT=300
a=1
while [ "$a" -le $LIMIT ]
do
lvcreate -L10M -ntv$a vg1
free
let "a+=1"
done
not ram problem
[root at fc3-i386-2 ~]# free
total used free shared buffers
cached
Mem: 255044 80704 174340 0 17776
47400
-/+ buffers/cache: 15528 239516
Swap: 522104 0 522104
[root at fc3-i386-2 ~]# lvextend --version
LVM version: 2.00.25 (2004-09-29)
Library version: 1.00.19-ioctl (2004-07-03)
Driver version: 4.4.0
shall i try new version?
ming
On Thu, 2005-07-28 at 15:49 -0500, Jonathan E Brassow wrote:
> yeah... it could be a memory issue which is causing the difference in
> active lvs.
>
> It could be the fact that he starts with _inactive_ lvs that allows him
> to create so many to start.
>
> To see if you are experiencing the same bug, you could 'vgchange -an
> <vol_name>' and then try to create a bunch of lvs... Then, once
> created, try to activate them.
>
> brassow
>
> On Jul 28, 2005, at 3:38 PM, Ming Zhang wrote:
>
> > i think this is strange that this guy can at least create 1500 lv but
> > fail to activate them all.
> >
> > here what i found is i even can not create ~300 lv.
> >
> >
> > ming
> >
> >
> > On Thu, 2005-07-28 at 15:32 -0500, Jonathan E Brassow wrote:
> >> I think the problem you are seeing is similar to the one found in
> >> bugzilla (164198). Would you be willing to add some notes there? It
> >> will give you a place to track the progress...
> >>
> >> https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=164198
> >>
> >> brassow
> >>
> >> On Jul 28, 2005, at 2:18 PM, Ming Zhang wrote:
> >>
> >>> On Thu, 2005-07-28 at 12:09 -0700, Nathaniel Stahl wrote:
> >>>> We'd like to be able to create a large number of LVs (potentially
> >>>> numbering in the low thousands). I get failure after LV 226 or so,
> >>>> though - "VG VolGroup01 metadata writing failed".
> >>>>
> >>>> RedHat claims this should be possible with LVM2 on the following web
> >>>> page:
> >>>>
> >>>> http://www.redhat.com/magazine/009jul05/features/lvm2/
> >>>>
> >>>> I admit to being a little suprised at the 2^32 max LV claim - I was
> >>>> figuring 2^20 as the theoretical max given 2.6's 32 bit device
> >>>> numbering
> >>>> scheme (20 bits for minor, 12 bits for major).
> >>>>
> >>>> The LVM2 code, at least version 2.00.25 as distributed in FC3,
> >>>> appears
> >>>> to have a check that the minor number is strictly less than 256.
> >>>> Removing this check allows for the creation of working LVs using
> >>>> minors
> >>>> greater than 256, but LV creation fails with the error "VG
> >>>> VolGroup01
> >>>> metadata writing failed" creating the 227th LV. Even with the minor
> >>>> limit in place - I can't create more than 226 LVs.
> >>>
> >>> i asked this question before. there is a hard coded limitation in lvm
> >>> metadata, so the real number is like this, limited around 2xx. the
> >>> limitation will be removed in near future. how near? i do not know.
> >>> :)
> >>>
> >>>
> >>>>
> >>>> Is there a patch that allows this limit to be broken? Should I be
> >>>> using
> >>>> a newer version of the tools? If not currently possible, is this
> >>>> something that will be in the near future?
> >>>>
> >>>> Thanks for any help/advice you can give.
> >>>>
> >>>> -Nate Stahl
> >>>>
> >>>> _______________________________________________
> >>>> linux-lvm mailing list
> >>>> linux-lvm at redhat.com
> >>>> https://www.redhat.com/mailman/listinfo/linux-lvm
> >>>> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
> >>>
> >>> _______________________________________________
> >>> linux-lvm mailing list
> >>> linux-lvm at redhat.com
> >>> https://www.redhat.com/mailman/listinfo/linux-lvm
> >>> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
> >>>
> >>
> >
>
> _______________________________________________
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