Johns Daniel <[EMAIL PROTECTED]> wrote:
> Essentially, this means there will be two SCSI
> controllers on a SCSI daisy chain. Is this allowed?
Yes, if they access drives on the SCSI bus, those drives support
multi-initiator, the two host adapter support other side initiated
recovery (SCSI RESET) and a protocol is maintained between the
two hosts through e.g. Ethernet for data/metadata synchronization.
If you want to add communication via SCSI between the two host
adapters, you need one of those to also support target mode
operations.
Neither target mode, remote initiated recovery nor metadata
synchronization are available on today's Linux, so maybe if you
state exactly your problem we will be able to help.
Target mode and remote initiated recovery support should be
quickly implementable (and I heard of some attempts at target
mode already, e.g. for IP over SCSI, alas I couldn't find
the implementation itself). For metadata synchronization
(such as: host A has just created a new file, has just
extended this file by N blocks, etc), even if take-over
recovery (HA feature) is not needed, you will need to heavily
change the VFS and/or buffer cache.
I know of no Linux project in this metadata synchronization area,
be it for performance (disk sharing) or reliability (takeover)
which intends to *really work* and fast (NO file serving
approach, only metadata exchange).
And have a nice new year :)
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