[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 22:03:23 UTC 2005 

thx for the information. seem fedora core 3 does not provide update to
lvm adn dm stuff. i will compile from scratch and try later.

ming

On Thu, 2005-07-28 at 17:00 -0500, Jonathan E Brassow wrote:
> I know that a similar bug (158687) has been fixed since your version... 
>   It is a somewhat similar bug, but I think the previously mentioned 
> applies to you more.  Still, it couldn't hurt to update.
> 
>    brassow
> 
> On Jul 28, 2005, at 4:26 PM, Ming Zhang wrote:
> 
> > 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/
> >>>>>
> >>>>
> >>>
> >>
> >> _______________________________________________
> >> 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/
> >
> 
> _______________________________________________
> 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/

More information about the linux-lvm mailing list