IBM Spectrum Scale (GPFS): On I/O with file size change on metanode takeover, the file size change may not be committed to disk

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Problem Summary:

A very small timing window exists in which a file size change, resulting from an append that happens on a non-metanode, may not be committed to the disk when that node takes over as metanode, leading to possible undetected data loss. If the data involved uses GPFS encryption (IBM GPFS 4.1.x or later), this may also result in undetected data corruption.

Users affected:

Users having applications which append to the same GPFS file from multiple nodes are potentially affected.

Recommendations: 

1. Any customer using affected IBM GPFS/IBM Spectrum Scale code levels and running applications which append to the same GPFS file from multiple nodes should upgrade to one of the GPFS product levels for which a PTF or efix is available to remedy this issue:

For IBM Spectrum Scale V4.2.0.0 thru V4.2.3.1, apply V4.2.3.2 which can be downloaded from Fix Central at https://www-945.ibm.com/support/fixcentral/swg/selectFixes?parent=Software%20defined%20storage&product=ibm/StorageSoftware/IBM+Spectrum+Scale&release=4.2.3&platform=All&function=all, or request APAR IV96760.

For IBM Spectrum Scale V4.1.1.0 thru V4.1.1.15, request APAR IV96776.

For IBM GPFS V4.1.0.0 thru V4.1.0.8, request APAR IV96776.

2. If you believe that your GPFS file system may be affected by this issue, you should contact IBM Service as soon as possible for further guidance and assistance.