| Title: | Optical Products |
| Moderator: | TAPE::SENEKER |
| Created: | Wed May 04 1988 |
| Last Modified: | Fri Jun 06 1997 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 841 |
| Total number of notes: | 3218 |
I was wondering why the Unix product for OSMS (V1.5) decided to
support dual-picker mode, vs. the OSMS/VMS product which doesn't? (yet?)
HP built this into these machines for a purpose, to speed up the
mechanical presentation of platters to drives, and I'm wondering if
theres some underlying reason its not being utilized.
It looked pretty impressive at HP when I was there, and they had one
of the large libraries running a test with dual-picker enabled, and
another, older library right beside it that didn't have that capability.
It sure seemed like twice the throughput of cartridges getting
into/out of the drives.
Steve
| T.R | Title | User | Personal Name | Date | Lines |
|---|---|---|---|---|---|
| 834.1 | currently not worth it | TAPE::SENEKER | which way to go? | Wed May 21 1997 10:58 | 13 |
The reason the VMS product does not use dual-picker is:
o Performance is only about 10% better when you are swapping all the
time, which means you are not transfering much data and your real
throughput is in the toilet.
o Design review and testing show the possibility of misplaced media
during error recovery which could lead to data integrity issues.
The amount of work to correct this problem is not justifiable based
on the performance gain or the delay it would cause for other areas
of product development.
Rob
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| 834.2 | Great, thanks... | CSC32::S_WASKEWICZ | Wed May 21 1997 11:09 | 5 | |
Thanks for the quick and concise reply. Now I know what to formally
explain to customers who question their libraries functionality.
Thanks again,
Steve
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| 834.3 | also in release notes | TAPE::SENEKER | which way to go? | Wed May 21 1997 12:01 | 18 |
The following text is also in the 3.4 release notes.
6 Known Limitations-Software
The RW531, RW532, RW551, and RW552 are mechanically able
to carry two optical cartridges at time in the robotics
mechanism. This feature allows these jukeboxes to insert a
new cartridge into the drive and to place the cartridge in
the drive back into a storage slot as one operation instead
of two operations. This "exchange" operation is slightly
quicker than two "move" operations. The OSMS software does
not use the "exchange" operation, at this time, because
the overall improvement impact to system throughput is
not sufficient to warrant the risk to data integrity. This
feature may be added in the future when the risk to data
integrity can be shown to be as good or better than the
present implementation using the "move" operations.
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