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In the MegaRAID SAS Software User Guide it is stated that a Drive Group includes one or more virtual drives. An excerpt from the document is:

"A virtual drive is a partition in a drive group that is made up of contiguous data segments on the drives. A virtual drive can consist of these components:

  • an entire drive group
  • more than one entire drive group
  • a part of a drive group
  • parts of more than one drive group
  • a combination of any two of these conditions."

My first question is the following: How can I create a drive group and inside that group have more than one virtual drive ?

In the User Guide there is just one relevant command, regarding drive groups. The guide says that this command creates a new drive group:

MegaCli –CfgLDAdd -RX[E0:S0,E1:S1,...] [WT | WB] [NORA | RA] [Direct |
Cached] [CachedBadBBU|NoCachedBadBBU] [-szXXX [-szYYY ...]] [-strpszM]
[-Hsp[E0:S0,...]] [-AfterLdX] | -Force [FDE|CtrlBased] [-Cache] [-enblPI
-val] -aN

In my opinion, running this command does not create a drive group.

My second question: Is a RAID Array the same thing as a Drive Group, in MegaRAID ? I am assuming they are the same thing.

What I actually want to achieve is to create a RAID Array , and in that array more than one virtual volumes.

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Drive group is essentially idea/concept. For instance, if you create RAID 1. You have two drives that make up this RAID 1. Two drives are Drive group. On those two drives you can have one or more virtual drives. Virtual drive can be considered as partition on this RAID 1 array / Drive group. If you want single virtual drive with maximum size (size of drive in drive group) you would do something like

megacli -CfgLdAdd -r1 [252:0,252:1] WB RA Direct CachedBadBBU -a0

however if you want to split your Drive Group in two virtual drives you can do it like this

megacli -CfgLdAdd -r1 [252:0,252:1] WB RA Direct CachedBadBBU -sz500GB -a0

megacli -CfgLdAdd -r1 [252:0,252:1] WB RA Direct CachedBadBBU -sz500GB -a0

These commands would create RAID 1 of drives in Enclosure 252, slot 0 and 1 with writeback enabled, readahead enabled, direct I/O cache policy, still use controller cache if battery goes bad (possibly trouble) and size (-sz500GB) as option if you want to use less than maximum space and have multiple virtual drives in drive group

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