Dell PowerVault ME5 Series Storage System CLI Reference Guide

• If the system has no disk groups, you can create either a linear or a virtual disk group. Whichever storage type you choose, the system will use that type for new disk groups. To switch to the other storage type, you must first remove all disk groups by using the remove disk-groups command.
• All disks in a disk group must be the same type (enterprise SAS, for example).

For virtual storage, a disk group of midline SAS disks will be used in the Archive tier. A disk group of enterprise SAS disks will be used in the Standard tier. A disk group of SSDs can be used:

• In the Performance tier (with the Performance tier license).
• As an all-flash array (without the Performance Tier license).
• As read cache. A virtual pool can contain only one read-cache disk group .

When you add a virtual disk group, the system will first prepare the disk group to be added to a virtual pool. During preparation, the disk group status will be VPREP and the disk group cannot be removed. When preparation is complete, the disk group will start initializing. During initialization, the disk group status will be INIT and the disk group will be available to store user data-or the disk group can be removed.

• All virtual disk groups in the same tier in a virtual pool should have the same RAID level, capacity, and physical number of disks. This will provide consistent performance across the tier.
• To replace a single-disk read-cache disk group with a multiple-disk read-cache disk group, simply remove the read cache and re-add it.

add disk-group

[assigned-to a|b|auto]

[chunk-size 64k|128k|256k|512k]

disks disks

[level nraid|raid0|r0|raid1|r1|raid5|r5|raid6|r6|raid10|r10|ADAPT]

[mode online|offline]

[pool a|b]

[spare <disks>]

[spare-capacity <size>[B|KB|MB|GB|TB|KiB|MiB|GiB|TiB]|default]

[stripe-width 8+2|16+2]

type linear|virtual|read-cache

[<name>]

Optional for linear storage. Prohibited for virtual storage. For a system operating in Active-Active ULP mode, this specifies the controller module to own the group. To let the system automatically load-balance groups between controller modules, use auto or omit this parameter. In Single Controller mode, this parameter is ignored; the system automatically load-balances groups in anticipation of the insertion of a second controller in the future.

Optional for linear storage. Prohibited for virtual storage. Prohibited for ADAPT.

For linear storage, this specifies the amount of contiguous data, in KB, that is written to a disk-group member before moving to the next member of the group. For NRAID and RAID 1, chunk-size has no meaning and is therefore not applicable. The default is 512k.

For virtual storage, the system will use one of the following chunk sizes, which cannot be changed:

• RAID 1: Not applicable.
• RAID 5 and RAID 6:
  • With 2,4, or 8 non-parity disks: 512k. For example, a RAID-5 group with 3, 5, or 9 total disks or a RAID-6 group with 4, 6, or 10 total disks.
  • Other configurations: 64k
• RAID 10: 512k

disks <disks>

Specifies the IDs of the disks to include in the group. For disk syntax, see Command syntax. The minimum and maximum numbers of disks supported for each RAID level are:

NRAID: 1 (linear storage only; not fault tolerant)

RAID 0: 2-16 (linear storage only; not fault tolerant)

RAID 1: 2

RAID 5: 3-16

RAID 6: 4-16

RAID 10: 4-16

ADAPT: 12-128

RAID 10 requires a minimum of two RAID-1 subgroups each having two disks. RAID 50 requires a minimum of two RAID-5 subgroups each having three disks. NRAID is automatically used for a read-cache disk group with a single disk. RAID 0 is automatically used for a read-cache disk group with multiple disks.

RAID 10 requires a minimum of two RAID 1 subgroups each having two disks. The system automatically uses NRAID for a read-cache disk group with a single disk, or RAID 0 for a read-cache disk group with multiple disks.

Required for a linear disk group. Required for a virtual disk group. Prohibited for a read-cache disk group. Specifies the RAID level to apply to the member disks.

Optional for a linear group. Prohibited for a virtual or read-cache disk group. Specifies whether the group is initialized online or offline.

• online: After a brief initialization period (seconds), the disk-group state is set toFTOL and I/O operations can be performed on the disk group. Subsequently, an initialization pass across the LBA extent is performed during which the existing data on the member data disks of the disk group is read, parity is generated, and only parity is written to the disk group (the data-area contents are preserved and not zeroed). This pass can take hours to complete on a large disk group. Online mode is the default for a linear disk group. Online mode is always used for a virtual disk group.
• offline: The disk group will be in an unavailable, offline (OFFL) state during the initialization process, during which zeros are written to all data and parity sectors of the LBA extent of the disk group. This can take hours to complete on a large disk group but is faster than online mode. When initialization is complete, the disk group state is set to FTOL and I/O operations can be performed on the disk group.

Required for a virtual or read-cache disk group. Prohibited for a linear disk group. Specifies the name of the virtual pool to contain the disk group. If the pool does not already exist, it will be created.

Optional for a linear disk group. Prohibited for a virtual or read-cache disk group. Prohibited for ADAPT. Specifies the IDs of from 1 to 4 dedicated spares to assign to a RAID 1, 5, 6, or 10 disk group. For disk syntax, see Command syntax. Only global spares are used for virtual disk groups.

Optional. For an ADAPT disk group, this specifies the target spare capacity.

• <size>[B|KB|MB|GB|TB|KiB|MiB|GiB|TiB]: Sets the target spare capacity to a specific size. The unit is optional (B represents bytes). If no unit is specified, GiB will be used, regardless of the current base. Whichever unit is set, internally the value will be rounded down to the nearest GiB. If the value is set to 0, the absolute minimum spare space will be used. If this parameter is omitted, the default setting will be used.

• default: Sets the target spare capacity to the sum of the two largest disks in the disk group, which is sufficient to fully recover fault tolerance after loss of any two disks in the group.

Optional. For an ADAPT disk group, this specifies the stripe width to use.

• 8+2: Each stripe contains 8 data chunks and 2 parity chunks. Including spare capacity equivalent to the 2 largest disks, the minimum disk-group size is 12 disks. This is the default.
• 16+2: Each stripe contains 16 data chunks and 2 parity chunks. Including spare capacity equivalent to the 2 largest disks, the minimum disk-group size is 20 disks. This option has less overhead, but also less redundancy, than the 8+2 option.

Required. Specifies the type of disk group to create.

• linear : A disk group for linear storage.
• virtual : A standard disk group for virtual storage.
• read-cache : A disk group for use as read cache for a virtual pool.

Optional for a virtual or read-cache disk group. Required for a linear disk group. Specifies a name for the new disk group. The name must be unique system-wide. Input rules:

• The value is case sensitive.
• The value can have a maximum of 32 bytes.
• The value can include spaces and printable UTF-8 characters except: " , < \
• A value that includes a space must be enclosed in double quotes.

# add disk-group type linear disks 1.20-21 level r1 spare 1.22 dg1

# add disk-group type linear disks 1.1-12 level adapt ALDG

# add disk-group type virtual disks 1.16-19 level r6 pool a

# add disk-group type virtual disks 2.1-12 level adapt pool b

# add disk-group type read-cache disks 1.18-19 pool b

expand disk-group

remove disk-groups

set disk-group

show disk-groups

show disks