X-Git-Url: http://git.samba.org/samba.git/?a=blobdiff_plain;f=Documentation%2Fcciss.txt;h=e65736c6b8bc890448c81de9ade727cee9f43ca4;hb=bb641ab496d5b8eb835ae1933926fdf23feb5260;hp=68a711fb82cf8d9d612363ff04bb71719ef6729f;hpb=033d974405276c22609c45d50167dd11df20aa82;p=sfrench%2Fcifs-2.6.git

diff --git a/Documentation/cciss.txt b/Documentation/cciss.txt
index 68a711fb82cf..e65736c6b8bc 100644
--- a/Documentation/cciss.txt
+++ b/Documentation/cciss.txt
@@ -20,15 +20,23 @@ This driver is known to work with the following cards:
 	* SA P400i
 	* SA E200
 	* SA E200i
+	* SA E500
 
-If nodes are not already created in the /dev/cciss directory, run as root:
+Detecting drive failures:
+-------------------------
 
-# cd /dev
-# ./MAKEDEV cciss
+To get the status of logical volumes and to detect physical drive
+failures, you can use the cciss_vol_status program found here:
+http://cciss.sourceforge.net/#cciss_utils
 
 Device Naming:
 --------------
 
+If nodes are not already created in the /dev/cciss directory, run as root:
+
+# cd /dev
+# ./MAKEDEV cciss
+
 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:
@@ -79,7 +87,7 @@ 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]*
@@ -133,3 +141,32 @@ 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.
+