sraw - benchmark raw scsi I/O performance under linux

sraw scsi-device [ bstart [ bstep ] ]

This program was written because of all of the whining on the SCSI channel about poor performance of the scsi drivers. This program basically reads the specified scsi device and measures the throughput. Note that the filesystem *AND* the buffer cache are bypassed by this code, this program was designed to benchmark the naked scsi drivers by themselves without the need to account for the overhead of any other portion of the kernel.

This program does a series of reads of the disk, of consecutive areas on the disk. The device is first queried to determine the sector size for the device, and then the series of reads is begun. About 5.0 Mb is read from the device, and then the performance numbers are reported. Note that since the buffer cache is completely bypassed, there is no need to be concerned about cache hits or anything.

Output of sraw is a set of lines, 4 numbers per line: blocksize, elapsed time, nblocks and throughput (in bytes per second).

bstart

starting block to check different zones on ZBR discs

bstep

factor for sequential stepping, default 1. Use 0 for reading always the same blocks (from cache)

sraw was written by Eric Youngdale.

sraw is available at

ftp://tsx-11.mit.edu/pub/linux/ALPHA/scsi/