Dell EqualLogic PS6210XS EqualLogic Host Integration Tools for Linux Version 1 - Page 88

Mounting and Unmounting Smart Copies, Mounting a Smart Copy, Mounting Read-Only Smart Copies

Page 88 highlights

Name: user-hourly Command: asmcli create schedule --keep 24 --comment "Hourly snapshot of user space" --type snapshot --source /source/VolB Name: user-hourly-all Command: asmcli create schedule --keep 24 --type snapshot --source /source/VolA /source/VolB 2 schedules found. # asmcli delete schedule --name user-hourly-all Successfully deleted schedule "user-hourly-all". # asmcli list schedule Schedules Name: user-hourly Command: asmcli create schedule --keep 24 --comment "Hourly snapshot of user space" --type snapshot --source /source/VolB 1 schedule found. Mounting and Unmounting Smart Copies Mounting a Smart Copy makes the file system contents available. This section provides the following information: • Mounting a Smart Copy • Unmounting a Smart Copy Mounting a Smart Copy Use the asmcli mount smart-copy command to mount a Smart Copy. For general information and prerequisites for mounting Smart Copies, see About Mounting Smart Copies. Mounting Read-Only Smart Copies ASM/LE creates a consistent Smart Copy by freezing all file systems at the same time. When a journaling file system is frozen, the journals are locked in a consistent state. In most cases, emptying the journal by performing all of the updates would take too long. Because the journals are an integral part of the file system, the frozen file systems are consistent as long as the changes in their journals can be replayed. If a mount command is used when the media is read-write and the file system is mounted with read-only access, the journals are replayed and the changes are made to on-disk structures, but no further changes can be made to the file system. A problem might occur if a file system journal contains critical updates but the media is read-only. For example, if a journal needs to be replayed but the iSCSI target has been switched to read-only access, the journal cannot be loaded because the updates to the on-disk structures cannot be made, and the mount command fails. On PS Series groups, this situation can be created by changing the access type of a volume from read-write to read-only or by changing a volume from a standard volume to a template volume. Some file systems offer the norecovery or noload option to mount the file system without replaying the journals. # mount -t xfs -r -o norecovery -o nouuid /dev/eql/temporary/1-e81da0-a541acdd9-a23a0a2be971b6b3+sample-xfs /mnt/temp This option can create inconsistencies if the modifications contained in the journals are needed to correctly reflect the state of the file system at the time that the target was copied. Changes to the file system that are only reflected in the journal are ignored. To avoid this situation, use the following process: 1. Mount the file system with read-write media. 2. Let the file system replay the journal. 88 Auto-Snapshot Manager Command Line Interface

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Name:
user-hourly
Command:
asmcli create schedule --keep 24 --comment "Hourly snapshot of user space"
--type snapshot --source /source/VolB
Name:
user-hourly-all
Command: asmcli create schedule --keep 24 --type snapshot --source /source/VolA /source/VolB
2 schedules found.
# asmcli delete schedule --name user-hourly-all
Successfully deleted schedule "user-hourly-all".
# asmcli list schedule
========================================================
Schedules
========================================================
Name:
user-hourly
Command:
asmcli create schedule --keep 24 --comment "Hourly snapshot of user space"
--type snapshot --source /source/VolB
1 schedule found.
Mounting and Unmounting Smart Copies
Mounting a Smart Copy makes the file system contents available.
This section provides the following information:
Mounting a Smart Copy
Unmounting a Smart Copy
Mounting a Smart Copy
Use the
asmcli mount smart-copy
command to mount a Smart Copy. For general information and prerequisites for mounting Smart
Copies, see
About Mounting Smart Copies
.
Mounting Read-Only Smart Copies
ASM/LE creates a consistent Smart Copy by freezing all file systems at the same time. When a journaling file system is frozen, the
journals are locked in a consistent state. In most cases, emptying the journal by performing all of the updates would take too long. Because
the journals are an integral part of the file system, the frozen file systems are consistent as long as the changes in their journals can be
replayed.
If a
mount
command is used when the media is read-write and the file system is mounted with read-only access, the journals are replayed
and the changes are made to on-disk structures, but no further changes can be made to the file system.
A problem might occur if a file system journal contains critical updates but the media is read-only. For example, if a journal needs to be
replayed but the iSCSI target has been switched to read-only access, the journal cannot be loaded because the updates to the on-disk
structures cannot be made, and the mount command fails.
On PS Series groups, this situation can be created by changing the access type of a volume from read-write to read-only or by changing a
volume from a standard volume to a template volume.
Some file systems offer the
norecovery
or
noload
option to mount the file system without replaying the journals.
# mount -t xfs -r -o norecovery -o nouuid
/dev/eql/temporary/1-e81da0-a541acdd9-a23a0a2be971b6b3+sample-xfs /mnt/temp
This option can create inconsistencies if the modifications contained in the journals are needed to correctly reflect the state of the file
system at the time that the target was copied. Changes to the file system that are only reflected in the journal are ignored. To avoid this
situation, use the following process:
1.
Mount the file system with read-write media.
2.
Let the file system replay the journal.
88
Auto-Snapshot Manager Command Line Interface