Data Domain DD400 Series, User Manual

Page: 57 / 300

Chapter 2: Disk Space and Backup Software 19
Reclaim Data Storage Disk Space
Reclaim Data Storage Disk Space
When your backup application (such as NetBackup or NetWorker) expires data, the data is marked
by the restorer for deletion. However, the data is not deleted immediately. The restorer
clean
operation deletes expired data from the restorer disks.
•
During the clean operation, the restorer file system is available for backup (write) and restore
(read) operations.
•
Although cleaning uses a noticeable amount of system resources, cleaning is self-throttling and
gives up system resources in the presence of user traffic.
•
Data Domain recommends running a clean operation after the first full backup to a restorer.
The initial local compression on a full backup is generally a factor of 1.5 to 2.5. An immediate
clean operation gives additional compression by another factor of 1.15 to 1.2 and reclaims a
corresponding amount of disk space.
A default schedule runs the clean operation every Tuesday at 6 a.m. (tue 0600) to clean 25% of the
total space available for data. You can change the schedule or you can run the operation manually
with the
filesys clean
commands. If you want to increase file system availability and if the
restorer is not short on disk space, consider changing the schedule to clean less often. See “Clean
Operations” on page 83 for details on changing the schedule.
You can have the clean operation run for a set number of hours or until a set number of gigabytes
are available on the restorer. The default (and maximum allowed in one operation) is 25% of total
space available for data, which takes from two to three hours on a system that is at least 25% full
and that is not otherwise busy. When the operation finishes, it sends a message to the system log
giving the percentage of storage space that was cleaned.
Manage File System Use of Disk Space
The restorer command
filesys show space
(or the alias command
df
) displays the amount
of disk space used for data storage and for restorer components.
# filesys show space
Resource Size GB Used GB Avail GB Use%
------------------- ------- ------- -------- ----
/ddvar 29.5 16.7 12.8 57%
Pre-compression - 6146.3 - -
Data 2870.6 881.5 1989.0 31%
If 100% cleaned* - - - -
Meta-data 19.7 0.1 19.6 0%
Index 120.0 8.7 111.2 7%
------------------- ------- ------- -------- ----
Estimated compression factor: 6.9x = 6146.3/(881.5+0.1+8.7
Estimate based on 2004/11/22 cleaning