Intel Raid Controller RS2BL040 Slow Performance – BBU problems.

Just for the record:

When BBU is not exists, the default cache policy is no cache. So, forcing it to use even BBU not present helped in that case the fsync value goes up to above 3000. There are still lower fsync values and jumping speed values, but now these are much better than before.
Summary: BBU is recommended using a system like this.

Check the system with the command:

# /opt/MegaRAID/CmdTool2/CmdTool264 -CfgDsply -aALL | egrep Cach
Default Cache Policy: WriteBack, ReadAdaptive, Direct, No Write Cache if Bad BBU
Current Cache Policy: WriteThrough, ReadAdaptive, Direct, No Write Cache if Bad BBU
...
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You need set these parameters:
Default Cache Policy: WriteBack, ReadAdaptive, Cached, Write Cache OK if Bad BBU <<<<<<<<<< !!!!!!!!!!!!!! Current Cache Policy: WriteBack, ReadAdaptive, Cached, Write Cache OK if Bad BB <<<<<<<<<< !!!!!!!!!!!!!!

# /opt/MegaRAID/CmdTool2/CmdTool264 -LDSetProp -CachedBadBBU -L0 -a0
                                     
Set Write Cache OK if bad BBU on Adapter 0, VD 0 (target id: 0) success

Exit Code: 0x00
# /opt/MegaRAID/CmdTool2/CmdTool264 -CfgDsply -aALL | egrep Cach
Default Cache Policy: WriteBack, ReadAhead, Direct, Write Cache OK if Bad BBU
Current Cache Policy: WriteBack, ReadAhead, Direct, Write Cache OK if Bad BBU
Disk Cache Policy   : Disk’s Default
Is VD Cached: No
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