[linux-lvm] LVM limit on PE's/size?
Scott P
pichelma at berbee.com
Thu Nov 29 08:52:02 UTC 2001
Heinz,
Thanks for clarifying further, I appreciate the extra info!
-Scott
"Heinz J . Mauelshagen" wrote:
> Scott,
>
> with your PE size of 32MB, you can achieve to create LVs up to 2TB in size
> (actually it is a little bit less than 2TB, because every LV can have up
> to 64K - 2 extents). You can have multiple 2TB LVs this way, because your
> VG capacity is in no means limited to 2TB! In theory you could have 128 SCSI
> IDs with 8 LUNs each providing up to 1 or 2TB in 1 VG.
>
> Because your PVs are smaller than 1TB in size, you will not suffer from
> the block adrdessing sign bit danger Andreas was explaining in his email.
>
> In general you should plan for the largest possible Logical Volume size
> during the lifetime of a Volume Group and set the Physical Extent size
> (vgcreate -s) acordingly. Even though Linux does not support more than 2TB
> per block device today, it will be in the future and you won't suffer from
> the LVM1 constraint ITR.
>
> Regards,
> Heinz -- The LVM Guy --
>
> On Tue, Nov 27, 2001 at 02:00:07PM -0600, Scott P wrote:
> > Andreas,
> >
> > Thanks so much for the insight!
> >
> > Here is some ouput, it looks like we might be ok?
> > Please comment, if possible, thanks...
> >
> > -Scott
> >
> > [root at ptb3 pichelma]# /sbin/pvdisplay /dev/sdb1
> > --- Physical volume ---
> > PV Name /dev/sdb1
> > VG Name exp300_2
> > PV Size 440.71 GB / NOT usable 26.75 MB [LVM: 176 KB]
> > PV# 2
> > PV Status available
> > Allocatable yes (but full)
> > Cur LV 1
> > PE Size (KByte) 32768
> > Total PE 14102
> > Free PE 0
> > Allocated PE 14102
> > PV UUID 1gKwp2-dotn-0WJU-5FwZ-uScI-OyMH-SHVw5F
> >
> >
> > [root at ptb3 pichelma]# /sbin/pvdisplay /dev/sdc1
> > --- Physical volume ---
> > PV Name /dev/sdc1
> > VG Name exp300_2
> > PV Size 440.71 GB / NOT usable 26.75 MB [LVM: 176 KB]
> > PV# 1
> > PV Status available
> > Allocatable yes (but full)
> > Cur LV 1
> > PE Size (KByte) 32768
> > Total PE 14102
> > Free PE 0
> > Allocated PE 14102
> > PV UUID ciUWIf-i9OO-okne-Fs6R-fjU1-NPpr-Ml4p8L
> >
> >
> > [root at ptb3 pichelma]# /sbin/pvdata -P /dev/sdb1
> > --- Physical volume ---
> > PV Name /dev/sdb1
> > VG Name exp300_2
> > PV Size 440.71 GB / NOT usable 26.75 MB [LVM: 176 KB]
> > PV# 2
> > PV Status available
> > Allocatable yes (but full)
> > Cur LV 1
> > PE Size (KByte) 32768
> > Total PE 14102
> > Free PE 0
> > Allocated PE 14102
> > PV UUID 1gKwp2-dotn-0WJU-5FwZ-uScI-OyMH-SHVw5F
> >
> >
> > [root at ptb3 pichelma]# /sbin/pvdata -P /dev/sdc1
> > --- Physical volume ---
> > PV Name /dev/sdc1
> > VG Name exp300_2
> > PV Size 440.71 GB / NOT usable 26.75 MB [LVM: 176 KB]
> > PV# 1
> > PV Status available
> > Allocatable yes (but full)
> > Cur LV 1
> > PE Size (KByte) 32768
> > Total PE 14102
> > Free PE 0
> > Allocated PE 14102
> > PV UUID ciUWIf-i9OO-okne-Fs6R-fjU1-NPpr-Ml4p8L
> >
> >
> >
> > Andreas Dilger wrote:
> >
> > > On Nov 27, 2001 11:34 -0600, Scott P wrote:
> > > > We are planning to add a 3 rd EXP300 array to out current server w/ 2
> > > > EXP300's in place already! We WILL surpass the 1 TB size, if possible?
> > >
> > > Depends if the driver does 32-bit block numbers with signed or unsigned
> > > values. The absolute maximum supported by 2.4 kernels is 2TB devices.
> > > I don't know if 2.2 will support > 1TB devices, but it is possible.
> > >
> > > > Linux ptb3 2.2.19 #2 SMP Tue Jul 24 11:53:29 CDT 2001 i686 unknown
> > > >
> > > > We are using:
> > > > lvm_0.9.1_beta7
> > > > reiserfsprogs-3.x.0j
> > >
> > > Get newer LVM tools, like 1.0.1, because the old ones have lots more bugs.
> > > Beta 7 has the PE alignment bug, so you should upgrade the tools even if
> > > you can't upgrade the kernel.
> > >
> > > > Here is the current filesystem and size:
> > > >
> > > > /dev/exp300_2/exp300_lv2 924160464 891307744 32852720 97% /files1
> > >
> > > > Q: Why are my logical volumes limited to 256 GB in size?
> > > > A: This is NO absolute limit but it depends on the physical extent size
> > > > you configured at volume group creation time.
> > >
> > > Check what "pvdata -P /dev/whatever" tells you about the PE size. If
> > > it is 16386kB, then you are limited to 1TB in size. If it is larger
> > > than that, you _may_ be able to go past 1TB, but you may not, depending
> > > on whether your drivers and kernel work properly or not.
> > >
> > > Cheers, Andreas
> > > --
> > > Andreas Dilger
> > > http://sourceforge.net/projects/ext2resize/
> > > http://www-mddsp.enel.ucalgary.ca/People/adilger/
> > >
> > > _______________________________________________
> > > linux-lvm mailing list
> > > linux-lvm at sistina.com
> > > http://lists.sistina.com/mailman/listinfo/linux-lvm
> > > read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html
> >
> >
> > _______________________________________________
> > linux-lvm mailing list
> > linux-lvm at sistina.com
> > http://lists.sistina.com/mailman/listinfo/linux-lvm
> > read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html
>
> *** 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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>
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