This message is from the T13 list server.
Keep in mind that the ATA 'streaming feature set' is still not widely
available.
Thank You !!!
-----------------------------------------------------------------
Jim Hatfield
Seagate Technology LLC
e-mail: [EMAIL PROTECTED]
s-mail: 389 Disc Drive; Longmont, CO 80503 USA
voice: 720-684-2120
fax....: 720-684-2711
==========================================
"Sheffield,
Robert L"
<robert.l.sheffie To
[EMAIL PROTECTED]> <[EMAIL PROTECTED]>
Sent by: cc
[EMAIL PROTECTED] <[email protected]>
rg Subject
No Phone Info RE: [t13] WRITE LONG, SCT Write
Available Long, and WRITE WRONG EXT
06/09/2005 11:25
AM
This message is from the T13 list server.
Ah... I see. I had assumed the Streaming Command Set was for tape
devices - but it looks like it's consistent with the characteristics of
block storage devices. I guess in SAT we could specify that if the
non-packet device supports the Streaming Command Set the SATL may
support a TB bit of one using the READ STREAM EXT or READ STREAM DMA EXT
command.
Thanks,
Bob
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of
[EMAIL PROTECTED]
Sent: Thursday, June 09, 2005 7:20 AM
To: Sheffield, Robert L
Cc: [email protected]
Subject: RE: [t13] WRITE LONG, SCT Write Long, and WRITE WRONG EXT
This message is from the T13 list server.
Bob,
The ability to recover whatever data is available after an error
uncorrectable by ECC is provided by the ATA Streaming Command Set. You
can
set the time limit and ask for the partially correct data. See the Read
Stream and Write Stream commands.
Best Regards,
Daniel J. Colegrove
Hitachi Global Storage Technologies
[EMAIL PROTECTED]
(702) 614-6119
"Sheffield, Robert L" <[EMAIL PROTECTED]>
Sent by: [EMAIL PROTECTED]
06/08/2005 05:47 PM
To
"Elliott, Robert \(Server Storage\)" <[EMAIL PROTECTED]>, <[email protected]>
cc
Subject
RE: [t13] WRITE LONG, SCT Write Long, and WRITE WRONG EXT
Along the thread of being helpful to SCSI-to-ATA Translation (SAT):
There's a related capability I think should be addressed ahead of the
Read/Write Long capabilities.
The SCSI SBC-2 standard defines the TB bit in the Read/Write error
recovery mode page as follows:
A transfer block (TB) bit set to zero specifies that the device server
shall not transfer a logical block to the
data-in buffer if the logical block is not recovered within the recovery
limits specified. A TB bit set to one
specifies that the device server shall transfer a logical block to the
data-in buffer before returning CHECK
CONDITION status if the logical block is not recovered within the
recovery
limits specified. The data returned
in this case is vendor-specific. The TB bit does not affect the action
taken for recovered data.
The net effect is the ability of a SCSI disk drive to transfer a block
of
data read from the media, even though there were
uncorrectable/unrecoverable errors. Presumably (though not specified)
the
disk would return data that matches the orignially written data except
for
the bits/bytes affected by the media defect. Without a comparable
feature
in the ATA command set, the only way SAT device can SATisfy (sorry) the
required behavior for a TB set to one is to manufacture the data - which
doesn't really meet the spirit of what the TB feature was intended to
accomplish.
Perhaps this could be done with some form of read/write long (or wrong),
but the problem with those commands is the ECC algorithm applied is
vendor-specific, and the host application needs to comprehend the
vendor-specific aspects of the device ECC algorithm in order to reliably
"plant" bad ECC that can be distinguished from an actual bad block. I'd
like to see a standard ATA command that allows retrieval of whatever
good
information can be extracted from a bad block that isn't dependent on
vendor-specific aspects of the ECC algorithm applied (i.e. doesn't
transfer the ECC bytes).
Bob
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of
Elliott, Robert (Server Storage)
Sent: Wednesday, June 08, 2005 5:11 PM
To: [email protected]
Subject: [t13] WRITE LONG, SCT Write Long, and WRITE WRONG EXT
ATA offers quite a few ways to perform WRITE LONG and READ LONG
functionality.
1. ATA-3 defined WRITE LONG (command codes 32h and 33h) and READ LONG
(command codes 22h and 23h), including a note that "The committe is
considering removing READ LONG and WRITE LONG commands in a future ATA
standard." The commands are obsolete in ATA-4.
2. The SCT (SMART Command Transport) technical report defines a way to
implement WRITE LONG and READ LONG commands through SMART log pages
(supporting 48-bit LBAs).
Command: SMART READ LOG, SMART WRITE LOG, READ LOG EXT, or WRITE LOG EXT
Log address: E0h (Writes) or E1h (Reads)
SCT Function code: 0001h (Read Long) and 0002h (Write Long)
Those log addresses are marked "Reserved" in ata7v1r4b.
3. Proposal e02126, defining new WRITE WRONG EXT and READ WRONG EXT
commands, has apparently been resurrected.
Any chance of converging on one method? If WRITE WRONG continues, then
a
SCSI equivalent would be helpful for the SCSI-to-ATA Translation (SAT)
project.
Since these commands each address a single logical block, it's unclear
how
well they will work with long physical sectors, where the ECC bytes are
shared by more than one logical block.
--
Rob Elliott, [EMAIL PROTECTED]
Hewlett-Packard Industry Standard Server Storage Advanced Technology
https://ecardfile.com/id/RobElliott
