RE: Request for review of Linux iSCSI driver version 4.0.0.1

[Roman Zippel <zippel@linux-m68k.org>]

Hi,

On Mon, 1 Dec 2003, Naveen Burmi wrote:

> In linux kernel there is a rare occurrence of data corruption. This data can
> be buffer cache data as well as raw I/O data. Don't know the actual root
> cause of the problem, but the fix that we put under macro
> "PREVENT_DATA_CORRUPTION" is capable of resolving this problem.

You probably mean the page cache and it's normal that a page can be
modified, while it's written out.

> On iSCSI target, 5428-2, upon detecting the CRC data error by the QlogicFC
> card it generates  the sense data with sense key as HARDWARE ERROR
> and Additional sense data as LOGICAL UNIT COMMUNICATION FAILURE.
> Upon receving this sense data iSCSI initiator driver is not retrying this
> command and failing the command to the upper layers of SCSI subsystem.
> But linux SCSI subsystem does not perform any error recovery for this kind of
> sense data.

The answer from the target is weird, why does it react with a scsi error
to an iSCSI transport problem?
At ERL0 the target should just drop the packet and/or close the
connection. Recovery of such case would require ERL1, where the target
could request to retransmit the corrupted data pdu or send a CHECK
CONDITION (but also with a different sense data).

bye, Roman