[179] in linux-scsi channel archive
Re: SCSI disk SPIN-UP on pwr-up ?
daemon@ATHENA.MIT.EDU (Rob Janssen)
Fri May 19 12:36:40 1995
To: linux-scsi@vger.rutgers.edu
Reply-To: pe1chl@wab-tis.rabobank.nl
Date: 19 May 95 13:07:11 DS
From: rob@sys3.pe1chl.ampr.org (Rob Janssen)
In <blevinD8s9xG.8Aq@netcom.com> blevin@netcom.com (Bryan Levin) writes:
>On many unix workstations, the scsi disks only spin up with a scsi command.
>As such, most hard drives (I've encountered) don't spin up until told to do
>so.
>However, on my linux system (with pcmcia 'new media bus toaster scsi-2 card')
>I can't get my external scsi drives to spin up. Should they (with 1.2.8
>kernel)?
>I have no problem doing I/O with drives that DO spin-up automatically at
>pwr-up (some are already jumpered to auto-spin up - but some don't have any
>docs or have NO jumpers!)
Hmmm strange... I have yet to encounter a disk that cannot spin-up
automatically at power-up. But probably they exist, especially when
you get your disks from systems that want no spin-up.
(special firmware version?)
>So, is the kernel supposed to send this scsi command? I scanned the source
>code but only found 1 occurence of "spin up", and it looks like it "should"
>spin up, but I am not a linux kernel hacker ;-)
I checked that part in hd.c and there may be a problem with it.
At the start of the function sd_init_onedisk a comment says:
/* We need to retry the READ_CAPACITY because a UNIT_ATTENTION is considered
a fatal error, and many devices report such an error just after a scsi
bus reset. */
But then, code has been inserted below that (and before the READ_CAPACITY)
that does not re-try the operation.
Probably the TEST_UNIT_READY fails with an error, and the disks are not
spun up.
Who added this spin-up code? Did it work?
Rob
