X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=Documentation%2Fcciss.txt;h=f74affe5c8297f58b4d36dfac566e7411899f2c5;hb=refs%2Fheads%2Fvserver;hp=7d8f67e5c8377a0309a7126deeaf5c6a1f7e2d5a;hpb=5273a3df6485dc2ad6aa7ddd441b9a21970f003b;p=linux-2.6.git diff --git a/Documentation/cciss.txt b/Documentation/cciss.txt index 7d8f67e5c..f74affe5c 100644 --- a/Documentation/cciss.txt +++ b/Documentation/cciss.txt @@ -14,28 +14,35 @@ This driver is known to work with the following cards: * SA 6400 * SA 6400 U320 Expansion Module * SA 6i - * SA 6422 - * SA V100 + * SA P600 + * SA P800 + * SA E400 + * SA P400i + * SA E200 + * SA E200i + * SA E500 -If nodes are not already created in the /dev/cciss directory +If nodes are not already created in the /dev/cciss directory, run as root: -# mkdev.cciss [ctlrs] - -Where ctlrs is the number of controllers you have (defaults to 1 if not -specified). +# cd /dev +# ./MAKEDEV cciss Device Naming: -------------- -You need some entries in /dev for the cciss device. The mkdev.cciss script +You need some entries in /dev for the cciss device. The MAKEDEV script can make device nodes for you automatically. Currently the device setup is as follows: Major numbers: 104 cciss0 105 cciss1 - 106 cciss2 - etc... + 106 cciss2 + 105 cciss3 + 108 cciss4 + 109 cciss5 + 110 cciss6 + 111 cciss7 Minor numbers: b7 b6 b5 b4 b3 b2 b1 b0 @@ -45,7 +52,7 @@ Minor numbers: | +-------------------- Logical Volume number -The suggested device naming scheme is: +The device naming scheme is: /dev/cciss/c0d0 Controller 0, disk 0, whole device /dev/cciss/c0d0p1 Controller 0, disk 0, partition 1 /dev/cciss/c0d0p2 Controller 0, disk 0, partition 2 @@ -73,7 +80,7 @@ the /proc filesystem entry which the "block" side of the driver creates as the SCSI core may not yet be initialized (because the driver is a block driver) and attempting to register it with the SCSI core in such a case would cause a hang. This is best done via an initialization script -(typically in /etc/init.d, but could vary depending on distibution). +(typically in /etc/init.d, but could vary depending on distribution). For example: for x in /proc/driver/cciss/cciss[0-9]* @@ -117,16 +124,42 @@ from the adapter, informing the SCSI mid layer may not be necessary. Note that the naming convention of the /proc filesystem entries contains a number in addition to the driver name. (E.g. "cciss0" -instead of just "cciss" which you might expect.) This is because -of changes to the 2.4 kernel PCI interface related to PCI hot plug -that imply the driver must register with the SCSI mid layer once per -adapter instance rather than once per driver. +instead of just "cciss" which you might expect.) Note: ONLY sequential access devices and medium changers are presented as SCSI devices to the SCSI mid layer by the cciss driver. Specifically, physical SCSI disk drives are NOT presented to the SCSI mid layer. The physical SCSI disk drives are controlled directly by the array controller -hardware and it is important to prevent the OS from attempting to directly +hardware and it is important to prevent the kernel from attempting to directly access these devices too, as if the array controller were merely a SCSI controller in the same way that we are allowing it to access SCSI tape drives. +SCSI error handling for tape drives and medium changers +------------------------------------------------------- + +The linux SCSI mid layer provides an error handling protocol which +kicks into gear whenever a SCSI command fails to complete within a +certain amount of time (which can vary depending on the command). +The cciss driver participates in this protocol to some extent. The +normal protocol is a four step process. First the device is told +to abort the command. If that doesn't work, the device is reset. +If that doesn't work, the SCSI bus is reset. If that doesn't work +the host bus adapter is reset. Because the cciss driver is a block +driver as well as a SCSI driver and only the tape drives and medium +changers are presented to the SCSI mid layer, and unlike more +straightforward SCSI drivers, disk i/o continues through the block +side during the SCSI error recovery process, the cciss driver only +implements the first two of these actions, aborting the command, and +resetting the device. Additionally, most tape drives will not oblige +in aborting commands, and sometimes it appears they will not even +obey a reset command, though in most circumstances they will. In +the case that the command cannot be aborted and the device cannot be +reset, the device will be set offline. + +In the event the error handling code is triggered and a tape drive is +successfully reset or the tardy command is successfully aborted, the +tape drive may still not allow i/o to continue until some command +is issued which positions the tape to a known position. Typically you +must rewind the tape (by issuing "mt -f /dev/st0 rewind" for example) +before i/o can proceed again to a tape drive which was reset. +