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Servers - Strip size setting for SSA RAID
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Problem Summary;
IBM SSA RAID Adapter for PC Servers - When configuring a RAID 5 Array, ONLY a 128 block Strip size is supported. The Adapter will hang if a Strip size of 32 blocks is used with 9.1 GB drives.

Problem Description:
Although the ONLY supported RAID 5 Array Strip size is 128 blocks, the IBM SSA RAID Adapter for PC Servers Configuration Utility will improperly allow the user to modify the Strip size from 32 - 128 blocks. When configuring a RAID 5 array using 9.1 GB drives and a Strip size of 32 blocks, the Adapter will no longer respond and in most cases the Operating System will hang and require a re-boot. The problem occurs on all 3 supported platforms - OS2 Warp Server, Windows NT 3.51 / 4.0, and Novell Netware 4.1 using 1800 level firmware / Configuration Utility.

Additional physical indications are that the entire SSA Loop will appear to be open - The second drive LED (Drive Ready LED) will flash on both the first and last drive of the installed configuration.

Drive Enclosure
Recovery Method:

1. Power off the SSA enclosure (3527 / 7133) which contains the drives selected when attempting to build the RAID 5 Array.

This procedure assumes that all of the members of the associated RAID 5 array are located adjacent to each other. If the associated RAID 5 array members (disk drives) are not located adjacent to each other, physically re-arrange them now.

2. Reboot the Server

3. Once the Operating system is up and running, unlatch the drives selected when the RAID 5 Array build was attempted, then power on the associated drive enclosure. Allow approximately 2 minutes for any remaining drives (not disconnected) to sequence up and come on-line.

The following step will need to be repeated once for each drive of the RAID 5 array. For example, if a 4+1 Array build was attempted, the following step would be repeated 5 times.

4. Reconnect 1 of the drives unlatched during the prior step and allow approximately 1 minute for the drive to sequence up and come on-line.

5. Bring up the SSA RAID Adapter Configuration Utility
- Select SSA ADAPTER LIST - press enter twice
- Select RAID 5 ARRAYS - press enter
- If the name of the failed RAID 5 Array build attempt appears, DELETE the Array. However, NO RESOURCES or prior successful arrays may be indicated. ONLY DELETE THE FAILED RAID 5 ARRAY.
- ESC to the prior menu
- Repeat steps 4 and 5 for each drive of the RAID 5 array which failed during the build attempt.

The attached SSA drive enclosure should no longer indicate an open loop condition and be operational.

The resolution for this problem will require a modification to the SSA Configuration Utility which will no longer allow the user to modify the Strip size when building a RAID 5 array and will be available in a future Driver release (Both the Drivers and Configuration Utilities reside on the Driver diskette of the associated platform utilized).

Work Around Solution:
When building a RAID 5 Array, DO NOT alter the Strip size field and use the default which is 128 blocks.
Document ID:  MCGN-3GVPAW
Last Modified:  2000-07-10
Copyright 2000 IBM Corporation
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