path: root/Documentation/blockdev
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Diffstat (limited to 'Documentation/blockdev')
1 files changed, 15 insertions, 0 deletions
diff --git a/Documentation/blockdev/cciss.txt b/Documentation/blockdev/cciss.txt
index 89698e8df7d4..c00c6a5ab21f 100644
--- a/Documentation/blockdev/cciss.txt
+++ b/Documentation/blockdev/cciss.txt
@@ -169,3 +169,18 @@ 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.
+There is a cciss_tape_cmds module parameter which can be used to make cciss
+allocate more commands for use by tape drives. Ordinarily only a few commands
+(6) are allocated for tape drives because tape drives are slow and
+infrequently used and the primary purpose of Smart Array controllers is to
+act as a RAID controller for disk drives, so the vast majority of commands
+are allocated for disk devices. However, if you have more than a few tape
+drives attached to a smart array, the default number of commands may not be
+enought (for example, if you have 8 tape drives, you could only rewind 6
+at one time with the default number of commands.) The cciss_tape_cmds module
+parameter allows more commands (up to 16 more) to be allocated for use by
+tape drives. For example:
+ insmod cciss.ko cciss_tape_cmds=16
+Or, as a kernel boot parameter passed in via grub: cciss.cciss_tape_cmds=8

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