3.7.0 HP StorageWorks HP Scalable NAS File Serving Software release notes for Linux (AG513-96006, October 2009)

DescriptionDefect
Invalid link count can be returned to NFS clients
Linux NFS clients running with Linux 2.4.x kernels will return an invalid link count via the
stat() system call interface if a file with multiple hard links is unlinked by one coincident
with a failover of a Virtual NFS Service. The unlink succeeds correctly in the server and the
correct link count is returned to the client, but the stat() system call on the NFS client will
continue to return the old link count. This situation may cause problems with programs that
unlink files with multiple hard-links and then use the stat() system call interface to verify
that the link count is what is expected.
This problem has not been observed on Linux NFS clients with 2.6.x kernels.
10646
Unmounting exported filesystem requires extra step
Before a PSFS filesystem can be unmounted, all processes must release their references on
the filesystem. The NFS server process retains these references on exported filesystems, and
prevents the filesystem from being unmounted.
To work around this problem, you will need to take the following steps to unmount a PSFS
filesystem that is being exported from an Export Group. (This procedure does not impact
other Export Groups exporting different filesystems via the same server.)
1. Disable the Export Groups that are exporting the filesystem to be unmounted. You will
need to disable the Export Groups on each server from which the filesystem is to be un-
mounted.
2. Run the command exportfs -ua on each server where the filesystem will be unmoun-
ted.
3. Unmount the filesystem from the servers. If you see a “device busy” message, run the
exportfs -ua command again and then repeat the unmount operation.
10742
Client mounts hang indefinitely
The standard Linux NFS implementation has a defect that prevents the successful export of
filesystems or directories that reside on certain devices. The symptom is that client mount
attempts hang indefinitely. The defect is not related to HP Scalable NAS or the PSFS filesystem.
The affected devices have major or minor device numbers greater than 255. To determine
if an exported directory is affected, take the following steps:
• Using df, determine the device on which the directory resides. The first column of output
contains the device name.
• Using ls -l <device_name>, determine the properties of the device. The comma-
separated fifth and sixth columns, (between the user/group information and the timestamp)
contain the major and minor device numbers.
If either number is greater than 255, directories on this filesystem cannot be successfully
exported by NFS.
The minor device number assignment cannot be controlled in any practical manner. It depends
on the order in which devices are discovered by the Linux operating system, and is not
guaranteed to be unchanged across reboots. Under normal circumstances, minor device
numbering is relatively stable across reboots but major changes in attached storage can have
major effects on numbering. The only absolutely guaranteed method to avoid this defect is
to limit the total number of raw devices plus partitions to less than 255, for any given major
device (such as PSD or PSV).
New filesystems intended for export by NFS should be created on devices or volumes with
minor device numbers substantially less than 255. Existing filesystems to be exported by NFS
must be copied from an affected device to one that will not be affected.
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