#: 13966 S1/General Interest
12-Jan-92 15:13:47
Sb: Hard Disks
Fm: Carl Kreider 71076,76
To: MM/ 1ers
I thought perhaps current and future MM1 owners might be interested in
the results of the testing I've done during the course of the development
of the disk drivers for the MM1.
The following chart shows transfer speed in bytes per second for the
drives I have tested on the MM1 with the dma driver. (The programmed I/O
driver wouldn't get above 25,000 on *any* drive). The test method is to
read some quantity of sectors repeatedly (not the same sectors, though)
until enough time has elapsed to give reasonable granularity. My rule of
thumb is that the test should last at least 100 time intervals (ticks or
seconds). By varying the quantity read, you can get some idea about the
overhead of the operating system and how the performance will vary with
application (copy moves big blocks at a time, while payroll may not).
The most obvious conclusion you can make is that speed is related to
cost. If you know the mechanics of the drives, it is also related to
cache size on the drive and raw data rate used internally on the drive.
It is also related to the speed of the micro on the drive (the ST296
doesn't seem to keep up at 1:1) and of course interleave.
Gulp ST2502 CP340 1:1 CP340 2:1 CP340 4:1 PRO210S ST296 1:1 ST296 2:1
1 110,376 29,537 28,532 26,546 27,235
2 204,600 56,676 44,384 47,127 53,773
4 332,222 99,864 82,241 76,260 97,541
8 500,812 176,602 134,217 110,376 161,319
16 906,876 279,620 195,083 137,518 239,679
32 1,177,348 390,167 250,406 159,783 524,288 57,852 322,638
64 1,636,801 479,349 294,337 172,960 838,860 381,300
128 1,720,740 479,349 294,337 171,196 1,198,372 381,300
256 1,766,022 516,222 310,689 176,602 399,457
512 1,864,135 524,288 316,551 178,481 409,200
Definitions:
Gulp How many sectors are read at once
ST2502 Segate 443MB 16 ms 5.25"
CP340 Conner 40MB ??ms 3.5", 2:1 means interleave of 2
PRO210S Quantum 210MB 15 ms 3.5"
ST296 Segate 85MB 281
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