Re: SCSI /dev/sg question

Kurt Garloff (garloff@suse.de)
Mon, 30 Aug 1999 16:21:56 +0200


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On Sun, Aug 29, 1999 at 05:34:48PM -0700, gokhan sozmen wrote:
> >But what do you want to achieve by sending SCSI commands via sg to the
> >adapter?=20
>=20
> Useful in certain situations. For example with
> most hardware RAID adapters the adapter creates=20
> virtual SCSI disks (called containers) and=20
> hides the details from the host.
>=20
> In such a system, if these virtual disks are
> not initialized (i.e. during virgin installation,=20
> you will not see any SCSI devices in /proc/scsi
> nor will there be a mapping of the driver to
> a /dev/sg file. However to create these virtual
> disks you have to send ioctl commands to the
> driver - hence the problem.

You need special tools to set up your SCSI config. I don't think, your
Hardware RAID will be configurable by SCSI commands sent to it.

If you have a hardware RAID, it should provide you the possibility to have
config data exchanged in some way. Maybe by providing a device which you can
IOCTL or talk to (and I would use a char device rather then simulate a SCSI
device), but preferably by a /proc/scsi/myraid/? interface.

I didn't look how the RAIDs in Linux do it, BTW. Have a look at the DAC960,
eata, gdth, megaraid, pci2xx drivers.

Regards,
--=20
Kurt Garloff <garloff@suse.de> Wuppertal, FRG
PGP2 key: See mail header, key servers Linux kernel development
SuSE GmbH, N=FCrnberg, FRG SCSI drivers: tmscsim(DC390), DC395

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