This agent has the following unique functionality and options for protecting
data:
The Image Level iDataAgent backs up
the blocks of complete volumes,
and restores them using
Volume Level
Restore or File
Level Restore. Each backup for the iDataAgent
on a Unix platform is either a CXBF backup or a non-CXBF backup.
CXBF backups are run on Unix platforms for this agent. To run a CXBF backup,
QSnap must be installed on the client
and you must configure a CXBF subclient.
For more information, see Subclients - SAN
iDataAgents. For a step-by-step
procedure, see Run a CXBF Backup (Image
Level/Image Level
ProxyHost).
Non-CXBF (Checksum) backups are run on Unix platforms for this agent. To run a
non-CXBF (Checksum) backup, you must configure a
non-CXBF (Checksum) subclient and also provide a
supported snapshot. For more information, see
Subclients - SAN
iDataAgents. For a step-by-step
procedure, see Run a non-CXBF Backup (Image
Level/Image Level
ProxyHost).
To facilitate the backup of data files for application such as Exchange and
SQL, PreScan and PostScan commands can be utilized to quiesce and unquiesce the
application during the backup. For more information, see
Pre/Post process commands.
To be able to back up Oracle instances with the Image Level iDataAgent,
the Oracle data files and Oracle archive logs must reside on two separate
volumes. In addition, the Oracle installation binaries, control file, and online
redo logs must reside in volumes other than the data files volume and the
archive logs volume.
During an Oracle backup, each Image Level subclient is expected to quiesce
one instance at a time. Do not configure an Image Level subclient's content with
more than one Oracle instance; create separate subclients for each Oracle
instance.
Multi-Streaming employs multiple data streams per subclient for data
protection operations. This enables the subclient's contents to be distributed to
all the streams, transmitting them in parallel to the storage media. Hence a subclient
whose data is secured using three data streams, utilizes more of the available network
resources, and can complete in as little as one third the time that the same data
would require using a single stream.
Note that, you do not have to enable
multi-streaming if you have multiple mount points pointing to the same physical
drive.
For Unix, multiple streams are supported for CXBF backups. Follow the steps given below to configure multi-streaming.
From the CommCell Browser, navigate to Client Computers |<Client>
| Image Level on Unix.
Right-click the <Subclient> in the right pane and
then click Properties.
Click CXBF.
In the Number of Data Readers box type or select the number of data
streams.
Select the Allow multiple data readers within a drive or mount point
check box.
Click the Storage Device tab.
In the Storage Policy list, click a storage policy name.
Click OK.
The number of streams configured in the Storage Policy
should be equal to, or greater than the specified Number of Data Readers
.
Image level backup performance on AIX clients can be increased by increasing the amount of data read
(chunk size) in
one attempt during backups. By default, the chunk size is 4096 Bytes. For a typical read size of 61440 Bytes, it will take 15 data read iterations to
complete the data fetch. If the chunk size is increased to 65536 Bytes, only one
data read iteration is needed.
Metadata contains information such as the directory structure and file
attributes. Metadata collection at the file level during backups is
necessary to perform file level restores. Metadata collection performance can be
enhanced using Data Classification. When Data Classification is used for
metadata collection, ACLs will not be available for restore
On a Unix platform, a CXBF device is a volume or partition that is monitored
by the CXBF block-filter driver. Consider the following when configuring a CXBF device:
CXBF devices should not be configured on Operating System file systems.
CXBF devices can only be configured on quiescent file systems (i.e.
unmountable or not busy).
Ensure that the Data Classification database is located on a
non Data Classification monitored volume and a non CXBF monitored volume.
At the Unix prompt on the client computer, type the command to define
the location of the Data Classification database
after navigating to the /opt/Calypso/Base
location:
DcClient -edit DB_FOLDER <dbpath>
The <dbpath> must exist prior to running
the command.
From the CommCell Browser, navigate to Client Computers |
<Client> | Image Level on Unix.
Right-click the <Subclient> and click Properties.
Click Volume Explorer, and then click Yes on the warning
dialog box.
Select the host connected to the volume you want to configure, and then
right-click the volume and select Configure CXBF device.
Click Configure in the Submit Configure Request dialog box.
Click OK.
At the Unix prompt on the client computer, type the command to start monitoring the CXBF mount point
after navigating to the /opt/Calypso/Base
location:
DcClient -monitor <mount path>
where: <mount path> is the
CXBF mount point that you
want to add to the monitoring list.
From the CommCell Console, navigate to Client Computers.
Right-click the <Client>, and then click Properties.
Raw device backups are enabled by default on AIX clients. However, you can
disable raw device backups and allow block device based backups using the following steps:
From the CommCell Console, navigate to Client Computers.
Right-click the <Client>, and then click Properties.
Selecting the
Skip Metafile
Creation option in the Advanced Backup Options screen will
increase performance but disables the ability to restore data using a File
Level restore. This will also apply to any Synthetic Full backups created
from such a backup.
If File Level restores will never be used for this client, instead of
manually selecting the Skip Metafile Creation option for each job, edit the
SkipMetaFileCreation
registry key to automatically skip metafile creation for all backup
jobs.
For the Image Level and Image Level ProxyHost
iDataAgents, if a backup job is
suspended either by the user or the Job Controller during metadata
collection, the job will automatically resume from the scan phase.
For increased logging of activities during data protection operations,
the
dEnableIBackupLog registry key can be created.
To alter the default snapshot chunk size, the
dSnapChunkSize
registry key can be created.
If the backup extent size is changed, the next backup will be converted
to a full backup.
For the Windows Image Level iDataAgent,
you can add volumes to existing subclient content or remove them. However,
whenever volumes are added or removed, the next backup job will be
converted to a full backup.
The cluster size (allocation unit) on any disk that you back up must
be greater than 1024 bytes if you intend to restore the data using a file level restore.
See Restore Data - Image
Level - File Level Restore.
For Solaris, under conditions of heavy I/O, such as is expected during
block-level backups and QR volume creation, we recommend that you do not enable
the UFS logging option on the client machine.
For Windows, before performing the first full backup of a volume, defragment it. This
will ensure that the minimum number of extents will need to be backed up,
resulting in better performance and lower storage requirements.
Although you can use the Image Level
iDataAgent to back up a virtual
server's volumes, you cannot use the Image Level
iDataAgent to restore directly to
a virtual server's volumes.
For the Image Level
iDataAgent on Unix, Unix File
System snapshots cannot be backed up by non-CXBF backup jobs.
You can not mix CXBF and Checksum backups.You can not perform a Checksum incremental followed by a CXBF full backup
or vice versa. Once you configure a volume as CXBF device, you cannot
include it in the subclient configured for Checksum backups.
