5. Filesystem/Storage Management
Some applications (e.g. dump and nfsd) try to improve disk I/O performance by distributing I/O requests to multiple processes or threads. However, when using the Completely Fair Queuing (CFQ) I/O scheduler, this application design negatively affected I/O performance. In Red Hat Enterprise Linux 5.5, the kernel can now detect and merge cooperating queues. Additionally, the kernel can also detect if the queues stop cooperating, and split them apart again.
This update introduces GFS2 support for the errors= mount command line option, which may assist in troubleshooting. The default option, errors=withdraw results in the filesystem attempting to withdraw from the cluster if an I/O error or metadata error is encountered. The alternative, errors=panic results in a panic in the same situation. (BZ#518106)
The Common Internet File System (CIFS) has been updated in the kernel. (BZ#500838)
