SCSI disk driver module spin-up problem (1.3.67)

Daniel Deckers (fh5y076@public.uni-hamburg.de)
Wed, 21 Feb 1996 23:39:03 +0100 (MET)

The scsi disk driver does not spin up drives when compiled as a module (this
problem has been around for a while). A quick fix would be as follows:

--- linux-1.3.67/drivers/scsi/sd.c
+++ linux-1.3.67/drivers/scsi/sd.c
@@ -970,3 +970,2 @@
/* Spin up drives, as required. Only do this at boot time */
- if (!MODULE_FLAG){
do{
@@ -1043,4 +1042,2 @@
}
- }; /* !MODULE_FLAG */
-

This has the disadvantage(?) of having sd_mod try to spin up any drive
behaving as though it were spun down each time sd_mod is reloaded.

I wonder if it might not be more useful to only spin up drives when they are
actually needed, be it at mount time or even only upon actual access. This
might be especially useful for drives used mainly as backup storage (e.g. to
keep source trees that only need to be accessed every other week)...

I expect that if support for spinning down scsi drives were to be added to
the kernel, such an approach would have to be taken anyways. The scsi-idle
patch available at sunsite, if it worked properly, would have basically
provided this -- is anyone still working on this one? I haven't seen any
replies to Martin Neuwirther volunteering to implement scsi power save
support into the kernel...

Any comments?

Yours,
Dan

[copies of this mail go to Eric Youngdale and Martin Neuwirther.]

-- 
Daniel_Deckers@public.uni-hamburg.de



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