This message is from the T13 list server.
Hale,
> Now the "real" question... Does any of this O/Q stuff matter? Doesn't
> SATA have something that replaces all this old PATA O/Q stuff?
I asked that same question several emails ago. There was discussions of
SATA-II having this. Best of my knowledge SATA-II wasn't going to add
functionallity though.....guess i need to go do some more reading.........
Gary Laatsch
[EMAIL PROTECTED]
----- Original Message -----
From: "Hale Landis" <[EMAIL PROTECTED]>
To: "T13 List Server" <[EMAIL PROTECTED]>
Sent: Monday, June 16, 2003 9:40 AM
Subject: [t13] generic problems with O/Q and the EXT commands
> This message is from the T13 list server.
>
>
> As I asked in the previous email, I don't see a proposal for the
> WRITE DMA QUEUED FUA command. But looking at the ATA/ATAPI-7
> description (both the general description of O/Q and the command
> description) I don't see a problem. Basically this command is a O/Q
> command (so it does not abort the outstanding command queue) but it
> is a command that is not allowed to release (so it executes like an
> non-O/Q command). Yes, that may be a big performance problem but that
> is the price you pay.
>
> HOWEVER, there is a big problem if the host is dumb and has
> outstanding O/Q commands, read and/or write, that access the same
> sectors that another O/Q command accesses (including the WRITE DMA
> QUEUED FUA command). Again, unless I missed something, I think
> ATA/ATAPI-x has nothing to say about the action and/or data integrity
> of O/Q commands that access the same sectors. I think when O/Q was
> added for hard disk drives T13 assumed this was the host's problem.
>
> But the O/Q EXT commands have yet another problem (that I have asked
> about before). If these commands are used with really large transfer
> lengths (remember that and EXT command can tranfer up to 65536
> secotors or about 33Mbytes of data) these commands have a real
> performance problem in that only one release/service cycle is allowed
> (and that must be before any data is tranferred). The ATAPI DMA O/Q
> option of the PACKET command allows a device to release/service
> multiple times (before and during the data transfer). O/Q EXT
> commands should allow the same for hard disk drives.
>
> Now the "real" question... Does any of this O/Q stuff matter? Doesn't
> SATA have something that replaces all this old PATA O/Q stuff?
>
> Hale
>
>
>
> *** Hale Landis *** www.ata-atapi.com ***
>
>
>
