enable disk cache policy for x3650 M3 ServeRaid Adapter M1015
I have to setup two new IBM x3650 M3 machines with 10 SAS drives and the built in ServeRaid M1015 adapted (manufactured by LSI AFAIK). Using the MegaRAID Storage Manager 6.90.0600 that I've downloaded from the IBM website I can setup a RAID 10 with 6 disks just fine (RAID 10 with four disks I've setup for the Windows 2008 R2 OS).
By default the MegaRAID software downloaded from IBM sets Access Policy = Read Write, Disk Cache Policy = Disable, Read Policy = No Read Ahead. Write Policy-IO Policy=Direct IO, Current Write Policy=Write Through and Default Write Policy=Write Through. All parameters can be changed but offer no other options as the one mentioned, except "Disk Cache Policy" can be set to "enabled".
The M1015 does not have a BBU so I guess this is the reason why the only option for example for Write Policy is "Write Through".
However I am wondering whether it is o.k. to set Disk Cace Policy to enabled ? WIth Disk Cache policy disabled I have around 120 MB/s seq write speed (tested with Diskmark) and with Cache policy enabled I have around 350 MB/s. (Read speed is 420 MB/s)
By default the MegaRAID software downloaded from IBM sets Access Policy = Read Write, Disk Cache Policy = Disable, Read Policy = No Read Ahead. Write Policy-IO Policy=Direct IO, Current Write Policy=Write Through and Default Write Policy=Write Through. All parameters can be changed but offer no other options as the one mentioned, except "Disk Cache Policy" can be set to "enabled".
The M1015 does not have a BBU so I guess this is the reason why the only option for example for Write Policy is "Write Through".
However I am wondering whether it is o.k. to set Disk Cace Policy to enabled ? WIth Disk Cache policy disabled I have around 120 MB/s seq write speed (tested with Diskmark) and with Cache policy enabled I have around 350 MB/s. (Read speed is 420 MB/s)
David
Is it OK? Sure, if you don't mind the extra risk of data loss in event of a controller failure, certain types of drive failures, power failure, or a BSOD. If you feel lucky, have a UPS, and back up often, go for it.
ASKER
dlethe, are you considering that the write policy setting is still "Write Through" when you wrote your comment ? Do you know exactly what the "enable" disk cache mean for this controller ?
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