mirror of
git://sourceware.org/git/lvm2.git
synced 2024-12-25 01:34:38 +03:00
87 lines
3.7 KiB
Plaintext
87 lines
3.7 KiB
Plaintext
Mondy 18th November 2002
|
|
========================
|
|
|
|
The new format of LVM metadata is ready for you to test!
|
|
We expect it to be more efficient and more robust than the original format.
|
|
It's more compact and supports transactional changes and replication.
|
|
Should things go wrong on a system, it's human-readable (and editable).
|
|
|
|
Please report any problems you find to the mailing list,
|
|
linux-lvm@sistina.com. The software has NOT yet been thoroughly
|
|
tested and so quite possibly there'll still be some bugs in it.
|
|
Be aware of the disclaimer in the COPYING file.
|
|
|
|
While testing, we recommend turning logging on in the configuration file
|
|
to provide us with diagnostic information:
|
|
log {
|
|
file="/tmp/lvm2.log"
|
|
level=6
|
|
}
|
|
|
|
You should schedule regular backups of your configuration file and
|
|
metadata backups and archives (normally kept under /etc/lvm).
|
|
|
|
Please read docs/example.conf and "man lvm.conf" to find out more about
|
|
the configuration file.
|
|
|
|
To convert an existing volume group called vg1 to the new format using
|
|
the default settings, use "vgconvert -M2 vg1". See "man vgconvert".
|
|
|
|
-M (or --metadatatype in its long form) is a new flag to indicate which
|
|
format of metadata the command should use for anything it creates.
|
|
Currently, the valid types are "lvm1" and "lvm2" and they can be
|
|
abbreviated to "1" and "2" respectively. The default value for this
|
|
flag can be changed in the global section in the config file.
|
|
|
|
Backwards-compatible support for the original LVM1 metadata format is
|
|
maintained, but it can be moved into a shared library or removed
|
|
completely with configure's --with-lvm1 option.
|
|
|
|
Under LVM2, the basic unit of metadata is the volume group. Different
|
|
volume groups can use different formats of metadata - vg1 could use
|
|
the original LVM1 format while vg2 used the new format - but you can't
|
|
mix formats within a volume group. So to add a PV to an LVM2-format
|
|
volume group you must run "pvcreate -M2" on it, followed by "vgextend".
|
|
|
|
With LVM2-format metadata, lvextend will let you specify striping
|
|
parameters. So an LV could consist of two or more "segments" - the
|
|
first segment could have 3 stripes while the second segment has just 2.
|
|
|
|
LVM2 maintains a backup of the current metadata for each volume group
|
|
in /etc/lvm/backup, and puts copies of previous versions in
|
|
/etc/lvm/archive. "vgcfgbackup" and "vgcfgrestore" can be used to
|
|
create and restore from these files. If you fully understand what
|
|
you're doing, metadata can be changed by editing a copy of a current
|
|
backup file and using vgcfgrestore to reload it.
|
|
|
|
Please read the pvcreate man page for more information on the new
|
|
format for metadata.
|
|
|
|
All tools that can change things have a --test flag which can be used
|
|
to check the effect of a set of cmdline args without really making the
|
|
changes.
|
|
|
|
|
|
What's not finished?
|
|
====================
|
|
The internal cache. If you turn on debugging output you'll see lots of
|
|
repeated disk reads, many of which will eventually get optimised out.
|
|
|
|
--test sometimes causes a command to fail (e.g. vgconvert --test) even
|
|
though the real command would work: again, fixing this is waiting for
|
|
the work on the cache.
|
|
|
|
Several of the tools do not yet contain the logic to handle full
|
|
recovery: combinations of pvcreate and vgcfgrestore may sometimes be
|
|
needed to restore metadata if a tool gets interrupted or crashes or
|
|
finds something unexpected. This applies particularly to tools that
|
|
work on more than one volume group at once (e.g. vgsplit).
|
|
|
|
Display output. Some metadata information cannot yet be displayed.
|
|
Work has started on new display tools.
|
|
|
|
Recovery tools to salvage "lost" metadata directly from the disks:
|
|
but we hope the new format will mean such tools are hardly ever needed!
|
|
|
|
|