更新时间:2022-05-29 17:30:42
使用PlateSpin复制居然会由于LVM的卷组VG没有空闲可用的空间(available free space in the LVM volume group)创建快照而导致失败,特此记录一下:免得每次都将卷组VG里面的空间全部使用完。在进行存储分配、规划时,如果有使用PlateSpin做复 制,一定要留意这个事情。
The
use of LVM snapshots is the default way of migrating hard drive
partitions on LVM logical volumes. Snapshots can be taken quickly and
allow for greatest inter-volume consistency.
For an LVM snapshot
to be created, there needs to be available free space in the LVM volume
group of the logical volume to be transferred. Free space in an LVM
volume group is space that has not been allocated to any logical volume.
The free space within each logical volume is not available for LVM
snapshot usage.
At the beginning of the volumes transfer stage, the PlateSpin software will create a new LVM snapshot for each LVM volume.
The
amount of space allocated to each LVM snapshot is based on its relative
characteristics (eg. size, usage). The software will attempt to create
snapshots of the appropriate size that will maximize the chance of
success during the transfer. In some cases, this may not be sufficient.
1.
In some cases, a snapshot of a logical volume will not be created due
to insufficient free space. In this case, the data transfer will
automatically fallback to using the block-based driver monitoring method
for that particular logical volume. (NotEnoughSpaceToCreateLvmSnapshot)
2.
In some cases, the rate of change of data on the volume may be greater
than the LVM snapshot can hold during the volume transfer. If this
happens, the snapshot will be invalidated and the transfer will fail.
(LvmSnapshotFailure)
Resolution
To resolve either of these possible issues, the system administrator can do one or both of the following:
1.
Increase the size of the free space on the volume group. This would
typically involve adding a new hard drive to the source workload and
extending the volume group to include the new hard drive. Once this is
done, the system will be able to make a better decision on snapshot
sizes.
2. Reserve space for use by a snapshot of a logical
volume. This space will be used as the backing store for the snapshot
of the logical volume during migration. To reserve free space, the
system administrator must create a new logical volume with a name suffix
of "-PS-user-snapshot" in the same volume group. At the beginning of
the data transfer, the volume will be temporarily replaced by a snapshot
of the same size. At the completion of the data transfer, the snapshot
will be deleted, and the “reserved” volume will be recreated.
For
example, to reserve 200MB for an LVM snapshot for a volume named
“/dev/myVG/myLV”, the system administrator must create a new volume with
the name “/dev/myVG/myLV-PS-user-snapshot”.
# lvcreate -L 200MB -n myLV-PS-user-snapshost myVG
This will create a 200MB volume named myLV-PS-user-snapshot on the myVG volume group.