Re: [PATCH][RFC 21/23]: iSCSI target driver

Vladislav Bolkhovitin
2008-12-12T19:26:23Z

Nicholas A. Bellinger wrote:
> On Wed, 2008-12-10 at 22:01 +0300, Vladislav Bolkhovitin wrote:
>> This patch contains iSCSI-SCST target driver. This driver is a heavily
>> modified forked with all respects IET
>> (http://iscsitarget.sourceforge.net). Modifications were aimed to make a
>> clearer, more reviewable and maintainable code as well as to fix many
>> problems and make many improvements. See
>> http://scst.sourceforge.net/target_iscsi.html for more details.
>>
>> It has split user/kernel space architecture, where all management,
>> sessions creation, parameters negotiation, etc. made in user space and
>> data are transferred in the kernel space. Such architecture for iSCSI
>> processing was many times acknowledged as the right one. Particularly,
>> in-kernel iSCSI initiator (open-iscsi) has such architecture.
>>
>
> Just as with the Open/iSCSI Initiator, IMHO I believe the split
> architecture design is difficult both to improve, debug and maintain,
> and provides *ZERO* additional benefit in the context of traditional
> iSCSI target mode for doing login and connection/session setup in
> userspace.
>
> Also, I appericate that you spent alot of time porting over IET code to
> your engine, but during our previous discussion you did not seem
> terribly interested in validation against core-iscsi-dv
> (http://linux-iscsi.org/index.php/Core-iscsi-dv) to test RFC-3720
> interopt and stability. Because the Core-iSCSI Initiator supports every
> possible parameter combination up to ErrorRecoveryLevel=0 defined in
> RFC-3720, the Core-iSCSI-Dv tests can run badblocks (or any too) to
> check data integrity for *EVERY* possible traditional iSCSI key
> combination and functionality for your iSCSI-SCST work, and any type of
> serious iSCSI-SCST production deployments.

The fact that nobody so far cared to do all those complicated and time
consuming rather academic tests doesn't mean that iSCSI-SCST won't pass
them. IET/iSCSI-SCST have been used for a long time in very different
setups, including xBSD and Solaris initiators on non-x86 architectures,
without any problems.

Vlad