HP StoreOnce Backup System Concepts and Configuration Guidelines (BB877-90913, November 2013)

has been running nonstop for a couple of hours), therefore if housekeeping is idle most of the
time no information will be displayed.
Figure 60 Housekeeping load graph
1. Housekeeping under control
2. Housekeeping out of control, not being reduced over time
In the above graph we show two examples, one where the housekeeping load increases and then
subsides, which is normal, and another where the housekeeping job continues to grow and grow
overtime. This second condition would be a strong indication that the housekeeping jobs are not
being dealt with efficiently, maybe the housekeeping activity window is too short (housekeeping
blackout window too large), or we may be overloading the StoreOnce appliance with backup
and replication jobs and the unit may be undersized.
Another indicator is the Time Idle status, which is a measure of the housekeeping empty queue
time. If % idle over 24 hours is = 0 this means that the box is fully occupied and that is not healthy,
but this may be OK if the % idle over 7 days is not 0 as well. For example, if the appliance is 30%
idle over 7 days then we are probably operating within reasonably safe limits.
Signs of housekeeping becoming too high are that backups may start to slow down or backup
performance becomes unpredictable. Corrective actions if idle time is low or the load continues
to increase are:
• Use a larger StoreOnce appliance or add additional shelves to increase I/O performance.
• Restructure the backup regime to remove appends on tape or keep appends on separate
cartridges – as the bigger the tapes (through appends,) the more housekeeping they generate
when they are overwritten.
• Increase the time allowed for housekeeping to run by reducing the housekeeping blackout
windows
If you do set up housekeeping blackout windows (up to two periods per day, 7 days per week),
be careful as you cannot set a blackout time from say 18:00 to 00:00 but you must set 23:59. In
addition there is a Pause Housekeeping button, but use this with caution because it pauses
housekeeping indefinitely until you restart it!
Finally, remember that it is best practice to set housekeeping blackout windows on both the source
and target devices. There is a worked example in HP StoreOnce Backup system Summary of Best
Practices with Sizing Tool and StoreOnce Catalyst worked examples.
108 Housekeeping