KB13@TE.CC.CMU.EDU.UUCP (02/09/87)
Things I think I know about Fujitsu 2361 "Eagles":
System Industries 9751, 9761, 9744 == Fujitsu 2351, 2361, 2344.
SI (and maybe Fujitsu) is discontinuing the 9761.
Several sites have reported high failure rates with these drives (Utah,
Harvard and Hughes Aircraft among them).
We purchased nine SI 9761-C (DEC RA-series emulators) a little over a
month ago and have had one problem, which was traced to a bad board in
the drive. They are connected through an HSC-70 to three 11/780s and
one 8650 in a cluster, but have seen little or no use so far (although
they have all been powered up). VMS version is 4.3 (or higher).
SI has (for at least Hughes Aircraft as well as several customers in the
Pittsburgh area) exchanged an equal-megabyte quantity of Fujitsu 2351
Eagles for failing 2361 drives.
The current revision level of the Head-Disk Assembly for Fujitsu 2361
drives is D0. If this new HDA replaces an older HDA in an existing
drive, then the drive also needs a complete re-calibration. If this is
not done, intermittent tracking and timing errors will keep system
managers awake nights on end.
Early (Rev A) drive failures were due to a problem with the bearings in
the HDA. Seems they seized up and expectable results followed. The
bearing assembly was re-designed and these problems are supposed to have
been eliminated.
Later (Rev B) drive failures were due to a cooling problem with the
boards inside the disk cabinet. A "hot spot" on one of the boards
caused an unusually high board failure rate. Slight modifications to
chip placement and airflow within the cabinet are said to have fixed
this.
Recent (Rev C) failures MAY (I say this because one person told me this)
have been traced to a manufacturing problem involving the incomplete
baking of lubricant onto the platter surface. Prolonged operation of
the drive causes pieces of the lubricant to become airborne inside the
HDA, collecting on one or more heads. This causes a rapidly increasing
number of bad sectors. However, when the drive is turned off and on
again, the heads "clean" themselves on the surface of the disk and the
unit may run for several weeks before enough lubricant accumulates on
the heads for the drive to begin failing again (sound familiar to
anyone?). The Rev D0 HDA is supposed to have a better-baked lubricant
on the disk platters and should not suffer from this problem.
SI is now pushing their 9744 (8") drive as an alternative to the
discontinued 9761. Faster transfer rate (3.0 MB/sec), smaller
form-factor (two drives fit side-by-side in a 19" rack), similar
capacity, similar pricing.
The local SI people have offered us 9744s (soon to be available in "C"
series) as replacements for any of our 9761s that fail.
-Ken Burner
Carnegie-Mellon
Arpa: KB13@TE.CC.CMU.EDU
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