Troubleshooting
Problem
How to diagnose why RAID (Device Parity) Fails to start.
Symptom
In DST or SST customer tries to start parity but gets the error:
Start Device Parity Protection Failed
There are no disk units eligible for the selected operation
due to one or more of the following reasons:
(see below for the reasons)
Cause
When starting RAID there are several layers of code involved.
DSM, slic IO, and the IOA firmware all play a role.
Diagnosing The Problem
While there are several possible causes the one that seems to trip up most customers (and the last one on the possible causes list they are shown) is the disk units are configured. That is they are in the an ASP.
So the 1st question to ask is:
Are the disks the customer wants in a RAID set configured units?
IF YES, then the only way to do this is with the system IPLED in B M
to DST. Forced DST using operator panel function 21 will NOT work.
Even when a system is IPL'd to DST Storage Management (also called Paging) can become active and block the start of RAID. The easiest way to tell if this has happened is to check the number of options that appear when Work With Disk Units is invoked.
When a system is at DST there will only be 2 options:
1. Work with disk configuration
2. Work with disk unit recovery
Whereas, when Storage Management is active, there will be 3 options listed:
1. Display disk configuration
2. Work with disk configuration
3. Work with disk unit recovery.
Resolving The Problem
If Storage Management (Paging) is active, a manual IPL to DST must be performed back to DST to start RAID.
If the Units are not configured, but RAID (Device Parity) still will not start then the possible causes as listed need to be investigated. Product Activity logs can also help. The hardware service provider may need to be engaged to assist as well.
Possible causes:
There are no disk units eligible for the selected operation due to one or more of the following reasons:
o All the device parity capable disk units are already device
parity protected.
o Maximum number of arrays exceeded.
o An IOP is in a condition that makes the disk units attached to
it read/write protected. Examine the 'Product activity log'
for any reference codes that are logged for the IO subsystem
and follow the appropriate procedure for the reference code to
correct the problem, if necessary.
o Not all disk units attached to an advanced function IOP have
reported to the system. Retry the operation.
o All the disk units in a parity set must be the same capacity
with a minimum number of either 3 or 4 units, and a maximum
number up to 18 units (depending upon the type of adapter)
in the resulting parity set.
o The type/model of the disk units is not supported for the
requested operation.
o If starting device parity protection beyond the
limited paging environment, all units in the
array must be non-configured. Otherwise device parity
protection must be started in the limited paging
environment.
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Document Information
Modified date:
18 December 2019
UID
nas8N1021983