6.9 Create Snap

create snap <name> <pool> <<device> <size>|<part>> [chunk]

Create a snapshot of an NSS pool.

nlvm [nlvm_options] create snap <name> <pool> <<device> <size>|<part>> [chunk]

For the stored-on location, you can specify the device and size, or specify an existing snap partition (type 1AC).

Command Options
name=snapshot_name

Mandatory. Specify the name of the NSS snapshot. This name must be a unique snap name on the server. The snap name is automatically converted to uppercase.

Pool snapshot names are 2 to 15 characters. The naming conventions are the same as for pools.

Example

name=POOL1SNAP
pool=pool_name

Mandatory. Specify the name of an existing pool that you want to snap.

Example

pool=MYPOOL1
device=devicename

Specify the device where you want to store the copy-on-write data for this snapshot. Use the size option to specify the amount of space to use on the device.

The device and size options are used instead of the part option.

Example

device=sdb
size=<value[K|M|G|T]|max>

Specify the amount of space to use on the specified device. The minimum size is 50 MB; there is no maximum. A snap partition (type 1AC) of the specified size is created on the specified device.

NSSMU restricts the maximum snapshot size to 8 TB.

Examples

size=20G
size=100.50M
part=<snap_partition>

Specify an existing, but currently unused, snap partition (type 1AC) where you want to store the copy-on-write data for this snapshot. Because the partition will be re-initialized and associated with this snapshot, it must not belong to any current snapshot. A snap partition can be used by only one snapshot.

Only a partition of type 1AC (snapshot) is allowed; all other partition types result in an error.

The part option is used instead of the device and size options.

Example

part=sdd3
chunk=chunk_size

Specify the chunk size of the snapshot in bytes. The default size is 64 KB. The chunk size must be a power of 2, with the minimum size of 512 bytes, and a maximum size of 256 KB.

Example

chunk=128K
Command Example
nlvm create snap name=POOL1SNAP pool=MYPOOL1 device=sdb size=20G chunk=128K

Create a snapshot named POOL1SNAP of pool MYPOOL1. The copy-on-write partition is on device /dev/sdb and of size 20 GB, and the snapshot chunk size is 128 KB.

nlvm create snap name=POOL2SNAP pool=MYPOOL2 part=sdd3 chunk=128K

Create a snapshot named POOL2SNAP of pool MYPOOL2. The copy-on-write partition uses an existing but unused partition /dev/sdd3 of type 1AC (snapshot), and the snapshot chunk size is 128 KB. The specified partition is re-initialized and assigned to snap POOL2SNAP.