6.1 HP IBRIX X9000 Network Storage System File System User Guide (TA768-96061, June 2012)

Tuning allocation policy settings
To optimize system performance, you can globally change the following allocation policy settings
for a file system:
• File allocation policy.
IMPORTANT: Certain allocation policies are deprecated. See “File allocation policies”
(page 195) for a list of standard allocation policies.
• Starting segment number for applying changes.
• Preallocation: number of KB to preallocate for files.
• Readahead: number of KB in a file to pre-fetch.
• NFS readahead: number of KB in a file to pre-fetch on NFS systems.
NOTE: Preallocation, Readahead, and NFS readahead are set to the recommended values
during the installation process. Contact HP Support for guidance if you want to change these
values.
On the GUI, open the Modify Filesystem Properties dialog box and select the Allocation tab.
Restore the default file allocation policy:
ibrix_fs_tune -f FSNAME {-h HOSTLIST|-g GROUPLIST} -p -U
Listing allocation policies
Use the following command to list the preferred segments (the -S option) or the allocation policy
(the -P option) for the specified hosts, hostgroups, or file system.
ibrix_fs_tune -l [-S] [-P] [-h HOSTLIST | —g GROUPLIST] [-f FSNAME]
200 Using file allocation