Write-Caching on JBOD SATA Drive is Erroneously Enabled by Default When Connected to Non-RAID SAS HBAs

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Write-Caching on JBOD SATA Drive is Erroneously Enabled by Default When Connected to Non-RAID SAS HBAs

1. Impact

On certain Sun StorageTek (non-RAID) SAS Host Bus Adapters (HBAs), original versions of the HBA firmware will instruct connected SATA drives to enable write caching when they are first seen by the HBA, which is contrary to standard operating procedure. In some configurations, SATA drives inside a JBOD (disk array) will by default be set with the write cache enabled by the HBA at boot time. Unless the application stack can tolerate this setting (e.g., certain ZFS configurations), data loss may occur if power is removed from the JBOD.

2. Contributing Factors

This issue can occur on the following platforms:

• Sun StorageTek SAS HBA with firmware 1.23.04.219 or earlier (HBA 375-3487-02 or earlier)
• Sun StorageTek ExpressModule SAS Host Bus Adapter with firmware 1.23.04.219 or earlier (HBA 375-3486-01 or earlier)

when connected to one or more JBODs.

Notes:

1. Any Sun StorageTek SAS HBA with a manufacturing part number of 375-3487-04 or higher contains a later version of firmware and is not affected by this issue.

2. The firmware version on an installed SAS HBA in a running system can be detected at runtime during the firmware upgrade procedure (referred to in the "Resolution" section below). Follow the procedure in the upgrade package through the point when the firmware version is displayed. At that point, the decision can be made whether or not to continue on to the actual upgrade step.

3. This issue can occur when all of the following conditions are present:


3. Symptoms

Loss of recently written data may occur.

4. Workaround

To avoid occurrence of this issue, install JBODs containing one or more SATA drives with UPS backup power available.  Until a firmware upgrade can be scheduled, do not power off these JBODs without properly quiescing I/O from the host system.

5. Resolution

This issue is addressed on the following platform:

• Sun StorageTek SAS HBAs with firmware 01.26.00.00 or later
  

The firmware upgrade package can be found at http://www.lsi.com/support/sun/

Note: SG-XPCIE8SAS-E-Z HBAs with part number 375-3487-01 cannot be upgraded with this package, but these parts are not supported with Sun JBOD storage (for other, non-related reasons).

In both cases, the new firmware will disable the write cache on all connected SATA drives at boot time or hotplug time.

To determine the firmware version of the HBA:

The product part number is displayed on the HBA itself. To check in a running system, it must be inferred from the firmware version on a card. Specific instructions (below) can be used to detect the firmware version.

SOLARIS: The firmware revision is a property named 'firmware-version' of the device in the output of 'prtconf -vp'.  Since this output can be difficult to decode, an alternative solution is to use the findHBA script contained in the LSI firmware update package.  This package can be found at http://www.lsi.com/support/sun/.  See the README.solaris file for guidance on how to run the detection utility to detect the firmware version.

OTHER OPERATING SYSTEMS: The firmware version is displayed in the output of the LSI "sasflash" utility.  This utility is contained in the LSI firmware update package, which can be found at http://www.lsi.com/support/sun.  See the README file for guidance on how to run the sasflash utility to detect the firmware version.

This Sun Alert notification is being provided to you on an "AS IS" basis. This Sun Alert notification may contain information provided by third parties. The issues described in this Sun Alert notification may or may not impact your system(s). Sun makes no representations, warranties, or guarantees as to the information contained herein. ANY AND ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT, ARE HEREBY DISCLAIMED. BY ACCESSING THIS DOCUMENT YOU ACKNOWLEDGE THAT SUN SHALL IN NO EVENT BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, PUNITIVE, OR CONSEQUENTIAL DAMAGES THAT ARISE OUT OF YOUR USE OR FAILURE TO USE THE INFORMATION CONTAINED HEREIN. This Sun Alert notification contains Sun proprietary and confidential information. It is being provided to you pursuant to the provisions of your agreement to purchase services from Sun, or, if you do not have such an agreement, the Sun.com Terms of Use. This Sun Alert notification may only be used for the purposes contemplated by these agreements.

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