[CentOS] formatting large volume

Craig White craigwhite at azapple.com
Wed Oct 15 18:13:08 UTC 2008


On Wed, 2008-10-15 at 13:34 -0400, Stephen Harris wrote:
> On Wed, Oct 15, 2008 at 09:52:03AM -0700, Craig White wrote:
> > I have done the pgcreate and tested lvcreate but wonder about
> > 'setphysicalextentsize' because in the man page, it states, "The default
> > of 4 MB leads to a maximum logical volume size of around 256GB" which
> > makes me think that if I want one volume when this is all done, I have
> > to increase that value.
> 
> The man page for "vgcreate" says "there is a limit of 65534  extents in
> each logical volume" but only for *lvm1* format.  lvm2 format doesn't
> have such restrictions.
> 
> I used default values for my 4Tbyte array (5*1Tbyte disk in a md raid5)
> under CentOS 4.
> 
SNIP...
> 
> Try using "pvcreate", "vgcreate" and "lvcreate" with no special options
> and see what happens.  It worked for me!
> 
> The default in CentOS should be lvm2; you can see that's what was
> created on mine by the "Format" line in the vgdisplay output.
> 
>   Format                lvm2
----
OK - well, I can delete the vg and the lv that I created and just
consider them as practice. I'm not really sure what the difference would
be having the physical extent size as 64 MB versions 4 MB.

I did run into a snag that I don't fully understand while trying to make
the filesystem though...

# mke2fs -v -j -l 2TbVol /dev/VolGroup10/2TbVol
mke2fs 1.39 (29-May-2006)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
274513920 inodes, 549011456 blocks
27450572 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=0
16755 block groups
32768 blocks per group, 32768 fragments per group
16384 inodes per group
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632,
2654208,
        4096000, 7962624, 11239424, 20480000, 23887872, 71663616,
78675968,
        102400000, 214990848, 512000000

read_bad_blocks_file: No such file or directory while trying to open
2TbVol

Obviously there is no physical disk to read a bad blocks file from and I
don't see in the man page for mke2fs any way to tell it to ignore bad
blocks or not search for the file.

Craig



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