FS System: QoS Migration from RAID 5 to RAID 6 Starting Automatically After Unmapping or Modifying LUNs

Asset ID:	1-72-2103614.1
Update Date:	2017-07-17
Keywords:

Solution Type Problem Resolution Sure

Solution 2103614.1 : FS System: QoS Migration from RAID 5 to RAID 6 Starting Automatically After Unmapping or Modifying LUNs

Applies to:

Oracle FS1-2 Flash Storage System - Version 6.2 and later
Information in this document applies to any platform.

Symptoms

The Oracle FS1-2 Flash Storage System automatically initiates a migration from RAID 5 to RAID 6 when a LUN is unmapped or modified in the following circumstance:

RAID 5 LUN was created using software and firmware version 6.1.x.
FS1-2 has been upgraded from 6.1.x to <=6.2.3.
RAID 5 LUN is unmapped or modified.

The following are events you would see in the event log. Although the timestamp for the event "LUN_MAPPING_HOST_DELETED" is after the event "CM_EVT_QOS_MIGRATION_STARTED", the QoS migration started at the time the customer un-mapped this volume.

2016-01-21T13:04:24.657 CM_EVT_QOS_MIGRATION_STARTED INFORMATIONAL ComponentName=/LINUX/RHEL6.3.4/TSM63PRDIF101_TSM63PRDIF102/TSM63PRDIF101_TSM63PRDIF102_vg_tsminst1_stg_02, Source=/CONTROLLER-02

2016-01-21T13:04:33.565 LUN_MODIFIED INFORMATIONAL ComponentName=/LINUX/RHEL6.3.4/TSM63PRDIF101_TSM63PRDIF102/TSM63PRDIF101_TSM63PRDIF102_vg_tsminst1_stg_02
2016-01-21T13:04:36.969 LUN_MAPPING_HOST_DELETED INFORMATIONAL ComponentName=/LINUX/RHEL6.3.4/TSM63PRDIF101_TSM63PRDIF102/TSM63PRDIF101_TSM63PRDIF102_vg_tsminst1_stg_02/10000090FA199D61

Changes

A RAID 5 LUN created using software and firmware version 6.1.x is unmapped or modified after the FS1-2 has been upgraded to <=6.2.3.

Cause

This is an unintended behavior and has been reported.

Solution

The FS1-2 now supports high-capacity hard disk drives up to 8 TB. Recovery time in a RAID 5 LUN for such a large device could present a potential risk of data loss should a second disk failure occur. For that reason, software and firmware version 6.2.x allows creation of RAID 6 LUNs but not RAID 5 LUNs on capacity hard disk drives.

The Oracle FS1-2 Flash Storage System Release Notes Release 6.2 stated the following:

Inhibit Single Parity for Capacity Disk Storage Classes

Beginning with Version 6.2.0, Oracle FS System prevents the creation of volumes with single parity (RAID 5) on the Capacity Disk Storage Classes. All new volumes are created with double parity (RAID 6) for added data protection in the event of a drive failure. Existing volumes created with single parity are not affected.

This is incorrect. Existing volumes with single parity (RAID 5) are affected because an automatic migration is initiated when RAID 5 LUNs created with software and firmware version 6.1.x are unmapped or modified.

The inaccuracy in the Release Notes has been corrected.
As from the release 6.2.7 (refer to <Document 1967797.1> FS System: How to Download Software and Firmware Updates for the FS1-2), for FS1 that created RAID5 type parity on Capacity Disk Volumes on releases below 6.2.x, it will generate a single alert for all the affected volumes. This is covered in our <Document 2191218.1> FS System: A System Alert for "Volumes Require Migration" Appears After Upgrading to Software Version 6.2.0 or Higher.

References

<BUG:22664072> - INCORRECT INFROMATION ABOUT SINGLE PARITY FOR CAPACITY DISK STORAGE CLASSES
<BUG:22601243> - LUN MIGRATION FROM RAID 5S TO RAID 6 AFTER UNMAPPING
<NOTE:2191218.1> - FS System: A System Alert for "Volumes Require Migration" Appears After Upgrading to Software Version 6.2.0 or Higher

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