[linux-lvm] LVM limits?
zxvdr.au at gmail.com
Fri Feb 1 05:40:21 UTC 2008
Jordi Prats wrote:
> I'm the system administrator of PADICAT (http://www.padi.cat). It
> collects Catalan (http://en.wikipedia.org/wiki/Catalonia) web sites to
> provide permanent access to them (http://www.padi.cat/en/quees.php).
> It's equivalent to Internet Archive (http://www.archive.org) but for a
> particular culture.
> Our software developers require us to have one large file system,
> actually a single directory, with all this historically-classified web
> sites on a gziped file.
> I'm currently studying lustre and other HPC-related file systems to get
> this large file system, but by now I have ext3 as our file system. Next
> Monday I'm planning to extend it to 3TB o 4TB, so I'm currently
> researching for restrictions because during next month I'll have between
> 3TB to 4TB more to add: so, it will become a 8TB file system.
> Last time I fsck my 2'1TB file system I spend about 2 hours. Anyway, I'm
> also curious about the maximums :P
The man page for vgcreate talks a little bit about limits:
"If the volume group metadata uses lvm1 format, extents can vary in size
from 8KB to 16GB and there is a limit of 65534 extents in each logical
volume. The default of 4 MB leads to a maximum logical volume size of
If the volume group metadata uses lvm2 format those restrictions do not
apply, but having a large number of extents will slow down the tools but
have no impact on I/O performance to the logical volume."
In short, you're more likely to reach filesystem limits before LVM's.
EXT3 has a theoretical limit of 32 TB, but 32 GB its not practical.
Creating an EXT3 filesystem larger than 8 TB is umm, brave - as you have
noticed the tools (eg. fsck) do not scale well w/ EXT3.
GFS or XFS (or others) may be more suitable, but it depends on your
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