tunefs_sfs(1M)

Synopsis

Description

The options are:

-a maxcontig

Specify the maximum number of contiguous blocks that will be laid out before forcing a rotational delay (see -d below). The default value is one, since most device drivers require an interrupt per disk transfer. Device drivers that can chain several buffers together in a single transfer should set this to the maximum chain length.

-d rotdelay

Specify the expected time (in milliseconds) to service a transfer completion interrupt and initiate a new transfer on the same disk. It is used to decide how much rotational spacing to place between successive blocks in a file.

-e maxbpg

Indicate the maximum number of blocks any single file can allocate out of a cylinder group before it is forced to begin allocating blocks from another cylinder group. Typically this value is set to approximately one quarter of the total blocks in a cylinder group. The intent is to prevent any single file from using up all the blocks in a single cylinder group, thus degrading access times for all files subsequently allocated in that cylinder group. The effect of this limit is to cause big files to do long seeks more frequently than if they were allowed to allocate all the blocks in a cylinder group before seeking elsewhere. For filesystems with exclusively large files, this parameter should be set higher.

-o [s | space | t | time]

Change optimization strategy for the filesystem. s and space are interchangeable, and t and time are interchangeable.

s or space

Conserve space.

t or time

Organize file layout to minimize access time.

Generally one should optimize for time unless the filesystem is over 90% full.

References

Notices