Including disk units in a parity set
When you attach a new disk unit to an existing
IOA that has device parity protection, you can include the disk unit
into an existing parity set with other disk units.
Including disk units
into an existing parity set with PCIe2, PCIe3, and newer generations
of SAS RAID adapters can result in a large performance degradation.
The degradation can occur because the adapter uses firmware in place
of specialized hardware assists when drives are included into an existing
parity set. For this reason, the Include disk operation is no longer
recommended with PCIe2, PCIe3, and newer generations of SAS RAID
adapters. Systems with POWER8® technology
and beyond do not allow the Include disk operation. Alternatives
for adding disk units to the system are to stop parity on the existing
set and then start parity with the additional disks in the set, or
to create a new parity set of three or more disks with the additional
disk units.If you want to
include a disk unit in a parity set and the disk units of that parity
set are in an independent disk pool, the independent disk pool must
be varied off. For all other disk pools, you must restart your system
to dedicated service tools (DST) mode before you can include them
in a parity set.
Adding three or more disk units requires you to create a new parity set. The include function does not work when creating a parity set. To create a parity set, go to Start device parity protection.
For a Small Computer System Interface (SCSI) IOA, the disk units being included must be the same capacity as the other disk units in the parity set. For a Serial Attached SCSI (SAS) IOA, the disk units being included can be the same capacity or larger than the other disk units in the parity set
To include a disk unit in a parity set, follow these steps:
- Select Configuration and Service from your IBM® Systems Director Navigator for i5/OS window.
- Select Disk Units.
- Select the disk unit that you want to include.
- From the Select Actions menu, select Include in Parity Set.
To include a disk unit in a parity set, follow these steps:
- In System i® Navigator, expand My Connections (or your active environment).
- Expand the System i you want to examine,.
- Select the disk units that you want to include.
- Right-click a selected disk unit and select Include in Parity Set.
- From the resulting dialog box, click Include to include the selected disk units in a parity set.