VERITAS File System 4.1 Release Notes (June 2006)

VERITAS File System 4.1 Release Notes
Software Issues in Base-VXFS
Chapter 124
system has 512 MB of memory, VxFS will require up to 52 MB to store the
VxFS inode cache. Therefore it is necessary to tune the tunables according
to the type of load on the system.
• Tuning Down the Inode Cache
VxFS file systems allocate and release inodes based on the file system load. Generally,
larger inode caches help the file systems to perform better in case of a file server or web
server load. The global tunable, vx_ninode, determines the maximum possible size of the
Base-VXFS inode cache. If the default value of vx_ninode is set to zero, Base-VXFS
automatically tunes the size of the inode cache at boot time, based on the size of the
physical memory on the system. On systems with a RAM size of less than or equal to 1 GB
per CPU, you can manually tune down vx_ninode to a value not less than that of nfile
(nfile is an HP-UX tunable that represents the maximum number of file descriptors).
The vxfsstat command can be used to check the current vx_ninode usage.
• Tuning Down the Buffer Cache
VxFS 4.1 implements a private buffer cache to use exclusively for metadata. The
allocations to this buffer cache vary during system usage based on file system load and the
maximum cache size specified in the global tunable, vxfs_bc_bufhwm. If the value of
vxfs_bc_bufhwm is set to zero, VxFS automatically tunes the maximum size of the
metadata buffer cache at boot time based on the system memory size. On systems with a
RAM size of 1 GB per CPU or less, you can manually tune down the value of
vxfs_bc_bufhwm to a minimum of 6MB.
• Full File System Cannot Be Resized
In some circumstances, the fsadm command cannot resize a 100% full file system due to
lack of space for updating structural information. If a file system is busy or too
fragmented, the resize operation fails.
• Data Integrity Issues with Disks and Disk Arrays with Write-back Caches
Disk drives configured to use a write-back cache, or disk arrays configured with a volatile
write-back cache, exhibit data integrity problems. The problems occur after a power
failure, SCSI bus reset, or other event in which the disk has cached data, but has not yet
written it to non-volatile storage. A workaround for this problem is to disable the
write-back cache.
• The fsadm Command Cannot Truncate a Directory
The fsadm command cannot truncate a directory if it has only one extent that is more
than two blocks in length, even if all the directory entries are deleted.
• Inode Limitation on File Systems Without Large File Support