SSC LOCATE Command Question

Gerry_Houlder at notes.seagate.com Gerry_Houlder at notes.seagate.com
Wed Jan 12 14:22:46 PST 2000


* From the T10 Reflector (t10 at t10.org), posted by:
* Gerry_Houlder at notes.seagate.com
*
Some work on this issue has already been started for Direct Access Devices. This
consists of defining new commands that have 8 byte LBA fields and 4 byte
transfer length fields. See documents 99-259 (by George Penokie) and 00-125 (by
Gerry houlder).Both are available from T10 web site (www.t10.org). Neither
document tries to address Sequential Access Devices because they were written by
people that don't typically work with that device type.

Perhaps you could read these two proposals and come up with a related proposal
directed at Sequential Access Device commands that need bigger address field. Is
LOCATE the only command affected or are there more?





Paul_A_Suhler at notes.Seagate.COM on 01/12/2000 03:25:06 PM

To:   t10 at t10.org
cc:    (bcc: Gerry Houlder)

Subject:  SSC LOCATE Command Question



* From the T10 Reflector (t10 at t10.org), posted by:
* Paul_A_Suhler at notes.seagate.com
*
The BLOCK ADDRESS field of the LOCATE command can specify up to 2^32 blocks.
With the large capacity tapes becoming available (e.g., LTO and Super DLT), a
200 GB tape could exceed this number of blocks if enough of the blocks were
small.  Granted, this would be a pathological case, but it would be a perfectly
legal one.

I can't find any discussion of this issue in the T10/T11.3/SSC working group
minutes from 1999.  Has it ever been discussed?  Is there a workaround?

(I could imagine using the BT bit to implement a vendor unique interpretation of
the block address as a relative address, and then issuing multiple LOCATEs, but
that's pretty horrible and we wouldn't want to do it.)

Thanks,

Paul

=-=-=-=

Paul Suhler
Seagate Removable Storage Solutions
714-641-2485


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