Zoning must be configured for tape usage - IBM BladeCenter SAS Connectivity Module, SAS RAID Controller Module

Resolving The Problem

Source

RETAIN tip: H203437

Symptom

When a Serial Attached SCSI (SAS) tape device is attached to a SAS Connectivity Module (NSSM) or SAS RAID Controller Module (RSSM), periodic drop of tape communications is seen.

The SAS switches are in a flat zone where every blade can see every external connected device.

Affected configurations

The system is configured with one or more of the following IBM Options:

• IBM BladeCenter S SAS RAID Controller Module, Option part number 43W3584, replacement part number 43W3630
• IBM BladeCenter SAS Connectivity Module, Option part number 39Y9195, replacement part number 39Y9193

This tip is not system specific.

This tip is not software specific.

Workaround

When using a tape device connected to the NSSM switch, zone the switch so that only one blade can see the tape device at a time.

Note: The external port can be configured for access by only one blade while keeping other blades on separate zones.

For the RSSM, create a zone in which all blades have access to all drives and access to the RAID controller. Separate zones must be configured for the blade-to-tape configuration:

1. A custom zone can be created by entering into the SAS switch portion of the RSSM and creating a user-defined configuration, with one zone have every blade with access to each drive and the RAID controller.
   
2. Create a second zone with the external port used on the RSSM for tape and the blade, which will own the communication. Once this is created, activate the configuration across both RSSMs.
   

The NSSM will need to add a zone to the existing configuration used with the external port to blade being used.

Additional information

The issue occurs as multiple blade operating systems attempt to utilize the tape device at the same time. Tape devices cannot be shared at the same time and need to be zoned separately and utilized as point to point.

If the switch is ever replaced, the zoning information must be re-applied to the switch before going into production.

Failing to do this could cause unexpected results.