LSI BBU Battery on RS/DVS systems

Rob Bennett -

This article applies to Rohde & Schwarz / DVS workstations and servers that uses the LSI MegaRAID controllers, such as: Venice, SAN MDS, servers and some Clipster/Fuze/Pronto.

Not all systems are equipped with BBUs on the MegaRAID controllers.



Q. How long is the life of the LSI battery.

A. It is depending on set up bbu mode. Between 1 & 5 years.

You can check the status with the following command in Linux: 

#>/opt/MegaRAID/MegaCli/MegaCli64 -AdpBbuCmd -getBbumodes  -aALL

If  "Battery Replacement required" says 'Yes', then the BBU or Supercap needs to be replaced.

If  "Pack is about to fail & should be replaced" says 'Yes', then the BBU or Supercap should be replaced soon.



Q. If the battery is dead will this effect overall disk performance?

A. If a bbu dies, all logical volumes, which write-back cache setting is 'Write-back with BBU', will disable the Write-back cache and therefore slow down writing performance to this logical volumes.

The default setting on a Venice should be  'Write-back with BBU' for the system and the meta logical volume and 'Always write-back' for the data volume. 



Q. What is the the recommended config set up regarding battery Re-lean?

A. By default the automatic re-learn cycles are disabled, because the re-learn process will temporarily (5+ hours per example below) disable the write-back cache and could cause drop frames.

In the MegaRAID Storage Manager event window you get these warning messages:

The BBU can be managed from the expanded list, right click on BBU to open the option menu.  

If no BBU is listed then BBU is not installed.


Event log of a learn cycle:




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