From mboxrd@z Thu Jan  1 00:00:00 1970
From: Vladislav Bolkhovitin <vst@vlnb.net>
Subject: Re: [RFC v2 16/21] tcm: Add PSCSI subsystem plugin
Date: Thu, 04 Nov 2010 16:14:51 +0300
Message-ID: <4CD2B1CB.6070004@vlnb.net>
References: <1285195867-11728-1-git-send-email-nab@linux-iscsi.org> <4CD01EE2.20705@panasas.com>
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To: Boaz Harrosh <bharrosh@panasas.com>
Cc: "Nicholas A. Bellinger" <nab@linux-iscsi.org>, linux-scsi <linux-scsi@vger.kernel.org>, linux-kernel <linux-kernel@vger.kernel.org>, FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>, Mike Christie <michaelc@cs.wisc.edu>, Christoph Hellwig <hch@lst.de>, Hannes Reinecke <hare@suse.de>, James Bottomley <James.Bottomley@suse.de>, Jens Axboe <axboe@kernel.dk>

Boaz Harrosh, on 11/02/2010 05:23 PM wrote:

[...]

>> +	 * Some pseudo SCSI HBAs do not fill in sector_size
>> +	 * correctly. (See ide-scsi.c)  So go ahead and setup sane
>> +	 * values.
>> +	 */
>> +	if (!sd->sector_size) {
>> +		switch (sd->type) {
>> +		case TYPE_DISK:
>> +			sd->sector_size = 512;
>> +			break;
>> +		case TYPE_ROM:
>> +			sd->sector_size = 2048;
>> +			break;
>> +		case TYPE_TAPE: /* The Tape may not be in the drive */
>> +			break;
>> +		case TYPE_MEDIUM_CHANGER: /* Control CDBs only */
>> +			break;
>> +		default:
>> +			printk(KERN_ERR "Unable to set sector_size for %d\n",
>> +					sd->type);
>> +			return NULL;
> 
> What about sector-less devices? OSD, Scanners, printers ...

[...]

>> +	/*
>> +	 * For TYPE_TAPE, attempt to determine blocksize with MODE_SENSE.
>> +	 */
>> +	if (sd->type == TYPE_TAPE) {
> 
> Just as a future note:
> One of the things I'm missing from LIO is the notion of SCSI_TYPE or SCSI
> class. So things like this can be done in a plugin manner as per TYPE
> Like in the Kernel we have the ULDs for that.

This is exactly how it is done in SCST.

Also SCST well handles sector-less devices.

Vlad