lphillips@lpami.wimsey.bc.ca (Larry Phillips) (07/13/89)
In <19640@louie.udel.EDU>, PROVERO@wsmr-simtel20.army.mil (Josh Rovero) writes: >On another note, what exactly *IS* MaxTransfer for in the mountlists? CLtd >doesn't say anything about this parameter in any of their docs, and the info >in the WB 1.3 manual is not exactly enlightening. Any help would be >appreciated. MaxTransfer is a limiting factor that tells the file system the largest size of a read or write request that the driver can handle. The file system, if it gets a larger request from a program, will break it up into smaller units before asking the driver to read. Leaving MaxTransfer out of the Mountlist tells the file system that reads or writes of any size are allowed, and any limtations of the controller/drive are handled in the driver itself. -larry -- Real Amiga hackers write printer drivers using Metascope. +----------------------------------------------------------------------+ | // Larry Phillips | | \X/ lphillips@lpami.wimsey.bc.ca or uunet!van-bc!lpami!lphillips | | COMPUSERVE: 76703,4322 | +----------------------------------------------------------------------+
PROVERO@wsmr-simtel20.army.mil (Josh Rovero) (07/14/89)
I, like others, would like to see some amplifying information on the
SCSIdirect standard. I have read scsidisk.(h|i), noted the similarities to
what the adaptec 4000 series manual says are the command formats, but am
still unclear how to use the standard.
Does anyone know if CLtd will be supporting the SCSIdirect standard?
On another note, what exactly *IS* MaxTransfer for in the mountlists? CLtd
doesn't say anything about this parameter in any of their docs, and the info
in the WB 1.3 manual is not exactly enlightening. Any help would be
appreciated.
Thanks in advance,
Josh Rovero PRovero@wsmr-simtel20.army.mil
KK1D@WD4MIZ packet radio
-------steveb@cbmvax.UUCP (Steve Beats) (07/14/89)
In article <19640@louie.udel.EDU> PROVERO@wsmr-simtel20.army.mil (Josh Rovero) writes: >I, like others, would like to see some amplifying information on the >SCSIdirect standard. I have read scsidisk.(h|i), noted the similarities to >what the adaptec 4000 series manual says are the command formats, but am >still unclear how to use the standard. > In a nutshell, SCSIDirect allows you to send SCSI commands directly to the device with minimal interference from the device driver itself. You should format the SCSI part of the command exactly as the devices programming manual tells you to. The rest is pretty much self explanatory from the scsidisk.(h|i) files themselves. It is important to set up data direction and length because some device drivers need to know this before the command phase is started (they aren't SCSI event driven in the true sense of the word). >Does anyone know if CLtd will be supporting the SCSIdirect standard? I don't know if the do/will, but they certainly should! >On another note, what exactly *IS* MaxTransfer for in the mountlists? CLtd >doesn't say anything about this parameter in any of their docs, and the info >in the WB 1.3 manual is not exactly enlightening. Any help would be >appreciated. > MaxTransfer is an ungodly kluge that I was forced to put into the filing system to help device driver writers who don't know how to break up an IORequest if it's too large for one SCSI read. The normal SCSI read command can only transfer 256 blocks in one go. A read request for more than 256 blocks can break some device drivers (boo, hiss). FFS often makes requests for more than 256 blocks, hence the need for MaxTransfer to limit these requests to more manageable sizes. MaxTransfer is not required for any of the Commodore hard disk drivers. >Josh Rovero PRovero@wsmr-simtel20.army.mil > KK1D@WD4MIZ packet radio > Steve Beats