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AVAMAR f_cache and p_cache Formulas

Hersey — Tue, 09 Jun 2009 14:08:22 +0000

Formulas to help determine the correct size of your f_cache and p_cache for AVAMAR backups.

f_cache = N * 40MB

N = Millions of Files
So for 3 million files:
f_cache = 3 * 40MB
f_cache = 120MB

p_cache = DB Size in GB/Average Chunk * 20MB

Average Chunk Sizes:
Exchange DB: 16
Microsoft SQL DB: 24

For a 100GB Microsoft SQL DB:
p_cache = 20/24 * 20MB
p_cache = 83.3MB

How to backup an Active Directory Domain Controller with AVAMAR

Hersey — Tue, 07 Apr 2009 12:08:04 +0000

Just some notes on backing up an Active Directory domain controller or the system state of any Windows client using EMC’s AVAMAR.
—

Install the AVAMAR client on the DC(s) to be backed up.

In the AVAMAR Administrator create a Dataset for the DCs (WindowsDC).

Use the Windows file system plugin and do not set any exclusions.

On the Options Tab check the Backup Windows System State check box and define a Backup label.

The AVAMAR client uses the NTBackup Utility to create a backup of the system state, it stores this backup in var in the avamar client install directory (C:\Program Files\avs\var\). If the space on that drive is limited you can set an attribute systemstatefile with a value of the full path to store the back up – D:\avs\SystemState.bkf (after you set the attribute/value make sure to hit + to add it)

Now create a Policy Group for the Dataset and set the schedule, retention, and add the clients (the AD Domain Controllers). Once you enable the group it will be run on the schedule or it can be run on demand.

When the backup runs the AVAMAR client first uses the Windows NTBackup Utility to backup the critical system state information such as the registry and the Sysvol directory.

Reference the AVAMAR System Administration Manual for more details on System State backup and restore.

AVAMAR Pre-backup Script to Mount Remote Shares on Celerra NAS

Hersey — Thu, 05 Mar 2009 15:29:44 +0000

When backuping shares on my Celerra using AVAMAR without a ndmp backup accelerator node I have to create a backup policy that connects to an avamar client on one of my servers and then runs a pre backup script to map a network drive to the remote share.

The script is just a .bat file that uses the NET USE command to map a network drive to the share on the Celerra. This worked fine, except I noticed that only files with read access for everyone were being backed up. All of my user profile or home directories were returning access denied errors. I did not want to grant everyone access to all files and directories.

To fix this I had to add a username and password to the NET USE command to map the drive as a user that has read access on all directories on the shares.

I created a backup admin user for this and set all files and directories to allow this user read access.

The pre backup script mount_x.bat now looks like this:

net use /delete X:
net use X: \\NAS\Share /USER:Domain\backupadmin password

Once the backup is complete I then run a post backup script to to remove the mapping with another script umount_x.bat:

net use /delete X:

The scripts have to be in C:\Program Files\avs\etc\scripts\ on the avamar client.