alen@crash.cts.com (Alen Shapiro) (12/22/89)
I have a Jasmine 180Mbyte Backpack (Fujitsu disk). Every 5.3 minutes,
the drive goes into self-test and isolates itself from the SCSI bus
for 2 to 2.5 seconds (I have written an access timing prog to confirm these
numbers). Jasmine say that the SCSI controller for the drive recallibrates
every 5 minutes since thermal changes in the drive require that it
rediscovers the relative head/disk position. At first they said that this should
not disrupt data-flow to the mac. After I wrote the test program that changed
to "it should not SIGNIFICANTLY disrupt the data-flow". I asked if this was
just preventative head movement so that stiction problems will not occur
to which I got a definite NO.
Although I am not held up for data EVERY 5 minutes - when I am in a
development cycle and get caught by the test, the delay is annoying.
I've had the drive for a month now and the self-test is as regular as clockwork.
I have recently upgraded one of 2 failed Rodime-based backpacks to a
130Mbyte Fuji-based drive (a story in itself). This drive arrived and
immediately on switching-on went into self-test/recalibration, where it
stayed for 6 minutes. Eventually it started the boot process which went
fine. 5 minutes later, the next scheduled self-test took the drive away for
20 minutes. I power cycled the drive and the problem went away.
I have been through this problem each day for 10 days now, each time, as
the drive warms, sucessive self-test episodes get shorter. Each time, if
I power-cycle the drive, the problem goes away until the next time
the drive is left off for an extended period (overnight).
AND NOW THE QUESTION FOR THE NET.
If the self-test is indeed a recalibration and not just stiction
avoidance with a "have I got where I expected to get" test, why
is it necessary to power-cycle the drive to get actual recalibration
to take place?
Does the net think it is reasonable for a drive to isolate itself for
2 seconds every 5 minutes to go do its own thing (best case when nothing
is found to be wrong).
I'm sending the drive back. With these kind of drive technologies though
can I even hope for a fix (to the 2 secs per 5 min thing).
Disclaimer - I have no connection with Jasmine and hope to have even
less connection with them in the future :-(
--alen the lisa slayer
...alen%shappy@crash.cts.com (a mac+ uucp host - what a concept)