Kofax Communication Server 9.1.1 - Manual (Page 78)

Environment Guide Version 3.00.04
78 © Copyright Kofax, Inc. All information is subject to change without notice.
It‟s recommended to use RAID 1+0 (mirrored sets in a striped set). Also possible is RAID 0 for each half of
a tandem system. RAID 5 is not recommended, it performs poorly on random writes.
Example: A HW RAID 1+0 using a RAID controller with 512MB Battery-Backed Write Cache (BBWC) option
and 8 hard disks with individual access times of 7 ms gives random write throughput figures of about 2000
writes per second. Each disk would allow 140 writes per second, so the RAID 1+0 is about 14 times faster,
of which a factor of 4 can be attributed to the striping and a factor of 3.5 to the optimizations done by the
RAID controller.
Hard Disk Performance Measurement
The write throughput of a given system can be measured using the TcDiskTest.exe utility. See chapter
“Using TcDiskTest Tool” above for a general description.
For measuring maximum write throughput use option “-p0” for no extra delay (this is the default). Specify
the drive with “-dc” (drive C) or “-dd” (drive D) and set a block size of 16 kByte using option “-b16”. Then
calculate the test file size, which should be comparable to the planned TCOSS file structure size, in number
of 16k blocks. The default “-i1000000” gives 1 million 16k blocks which results in a test file size of about 16
GB. Option “-e0” leaves the test file on disk after the test, this is useful for running repeated tests. The
option “-t60” lets the test run for 60 seconds, default would be unlimited test duration.
Example: TcDiskTest –dc –b16 –e0 –t60
TcDiskTest starts by creating the test file “C:TcDiskTest.bin” and then reports the number of disk writes per
second every 10 seconds.