Chapter 2
ptx/RAID V2.2.0

ptx/RAID V2.2.0 provides the device driver and administration utilities for a Disk Array Subsystem (DASS) on a SCSI channel. This release will support up to 10.1 TB of data storage on a single NUMA-Q system running DYNIX/ptx V4.6.0. High data availability, capacity, and protection are achieved by configuring disk arrays in the DASS unit with RAID-5 striping and parity-based data reconstruction. RAID-0, RAID-1, and RAID 1/0 functionalities are also supported. Hardware fault protection is increased with the Application Transparent Alternate Path (ATAP) feature.


2.1 System Prerequisites


2.1.1 Supported Configurations

The following configurations are supported:


ATTENTION

DASS units are regarded by DYNIX/ptx V4.6.x as shared devices even if only one host node is connected to them.



2.1.2 Software Requirements

The ptx/RAID Version 2.2.0 with ATAP functionality requires the following software:


2.1.3 Disk Space Requirements

The ptx/RAID V2.2.0 product requires approximately 1.5 MB of free disk space in the root filesystem and 3.5 MB of space in the /usr filesystem for installation.


2.1.4 Hardware Configuration Requirements

The ptx/RAID Version 2.2.0 with ATAP requires the following hardware:


2.2 Changes Since the Previous Release

ptx/RAID V2.2.0 is a minor release containing the following changes:


2.3 Software Installation

To install and configure your system for ptx/RAID, perform the following steps:

  1. Install the ptx/RAID software product following the instructions in the DYNIX/ptx V4.6. and Layered Products Software Installation Release Notes.

  2. Download LIC code version 9.56.03. See Section 1.3 for details.

  3. Open the file /usr/conf/uts/io/scsidisk/scsidisk_space.c. Check that the following parameter is set as shown. The unit of value is seconds.

    int scsidisk_standard_timeout = 150;
  4. Build (configure and compile) the kernel on non-clustered systems as described in the DYNIX System Configuration and Performance Guide. Then reboot the system using the new kernel.

The ptx/RAID software installation is now complete.


2.4 ptx/RAID Caveats and Limitations

The following caveats and limitations apply to CLARiiON DASS devices when connected to NUMA-Q systems:

The ptx/RAID V2.2.0 software does not support the following functions:


2.5 Problem Report Summary

This section describes known problems in ptx/RAID V2.2.0.

The number that appears in the title of each problem report is the problem-tracking-system number assigned to the report. These problem reports will be fixed in a future release unless otherwise noted.

227629
During ptx/RAID failover the system can hang waiting for commands.

In rare cases, during a ptx/RAID failover operation, I/O to the affected DASS may be suspended for several minutes as a result of cascading command timeouts caused by driver-initiated retries. Applications intolerant of these delays may be negatively affected. The resultant behavior is unpredictable and application-specific.

Workaround. Application-dependent. Contact Customer Support for more information.

228457
VTOC for 9 GB CLARiiON disk module wastes disk space.

The CLARiiON RAID VTOC description file rd5_5x9gb contains an error which wastes 101000 sectors of disk space.

Workaround. Partition #9 should start on sector 3686808, not sector 3696908. Move up all of the following partitions accordingly, or add the extra space to the last partition on the disk, or create a new partition at the end of the disk to use the space.

238447
atapctl -c on a cluster node causes other nodes in the cluster to mark the path as dead.

If the atapctl -c rdn command is run on one node in the cluster, an I/O error will occur when other nodes in the cluster try to send data down the now available path. Eventually all other nodes in the cluster will mark the previously active path as dead.

Workaround. Manually recover the dead paths using the atapctl -r rdn command.

238479
The ffutil utility cannot distinguish RAID devices in a multipath configuration when both SPs are on the same SCSI bus.

Workaround. If both SPs are on the same bus, manually deconfigure the RAID devices before running ffutil. The following example shows how to deconfigure RAID devices using devctl.

# devctl -d rd0
devctl: deconfiguring rd0 from scsibus4, scsibus5
devctl: deleted rd0

242732
MAKEDEV.rd creates devices with wrong minor numbers.

MAKEDEV.rd creates device files with incorrect minor numbers, and should not be used. Because devctl automatically creates and modifies device files, there is no need to use MAKEDEV.rd.

Workaround. Use devctl.

243302
raiddisp command does not display LUN numbers.

In both the default RAID-5 configuration and mixed RAID configurations within a DASS unit, the raiddisp command fails to indicate the numbers assigned to the LUNs; instead, it displays asterisks where the LUN numbers should be.

Workaround. Use the Grid Manager utility over a serial connection to display the LUN numbers properly. See the NUMA-Q® Administration Guide for CLARiiON® Disk Arrays for details.

246815
Deconfiguring rd devices on a SCSI bus can hang the bus when reconfiguration is attempted over FC bridge

This problem is seen when all the following conditions exist:

Workaround: Disable TIN on the DASS unit. The procedure for disabling TIN assumes that your system has the following hardware, software, and firmware versions:

249145
raiddown does not work with VTOC installed on a clustered system

Workaround: Use the devdestroy command to remove all VTOCs for all LUNs in a given DASS.

249154
diskid does not display rd serial numbers

Workaround: None.

250596
Deconfiguring rd device with active I/O panics the system

If an rd device is accessed by any means other than a VTOC or ptx/SVM, deconfiguring the rd device while it is open can panic the system.

Workaround: Before deconfiguration, make sure that no raw rd devices are in use.