I would like to setup a limited-size RAID 10 array for the OS with write-through enabled for safety (no battery/UPS), and use the rest of the disks in a RAID 0 with write-back enabled for performance (data is replacable). This is with a LSI MegaRAID SAS 9260-4i using the latest firmware 12.15.0-0239

Setting up the RAID 10 works OK like:

megacli -CfgSpanAdd -r10 -Array0[252:0,252:1] -Array1[252:2,252:3] WT RA Direct NoCachedBadBBU -sz500GB -a0 Adapter 0: Created VD 0
Adapter 0: Configured the Adapter!!
Exit Code: 0x00

But then I can't seem to get the RAID 0 added with the rest of the space. i.e.

megacli -CfgLdAdd -r0 [252:0,252:1,252:2,252:3] WB RA Direct CachedBadBBU -a0
Drives are not consistent with configured Array.
Exit Code: 0x03

Or trying to add it as another span instead

megacli -CfgSpanAdd -r0 -Array0[252:0,252:1,252:2,252:3] WT RA Direct NoCachedBadBBU -a0
Invalid input at or near token WT
Exit Code: 0x01

megacli -CfgSpanAdd -r0 [252:0,252:1,252:2,252:3] WT RA Direct NoCachedBadBBU -a0
Invalid input at or near token [252:0,252:1,252:2,252:3
Exit Code: 0x01

Or just guessing

megacli -CfgAllFreeDrv -r0 WB RA Direct CachedBadBBU -a0
No Configurable Disk Available for Configuraiton on Adapter 0.

Is it just not possible to have multiple raid groups on the same disks with MegaRAID? or do I need to somehow create the two virtual disks before configuring them? Probably would be easier with a GUI but trying to do this all remotely via megacli.

  • Just went with raid 5 as a comrpomise – Jeremy May 29 '18 at 21:55

Most hardware RAID controllers can only use complete disks for volumes (I am not aware of any model that can use only part of a disk for this).

Use software RAID if you need this or add a pair of disks for the system volume.

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