[Scst-devel] Finer grain locking in scst_sysfs

[<sha...@ka...>]

We are using SCST in a clustered SSD storage using FC and iSCSI 
connectivity.
We are seeing problems when we attempt to perform multiple volume mappings.
By problems I mean 2 things:
1. I/O is quiesced during these operations
2. Initiators get unit attentions due to the mapping changes which cause 
a lot of noise

I reviewed the implementation of scst_sysfs and this seems to be by 
design, since during these operations both SCST mutex is taken and IO is 
quiesced.

Are there any plans to introduce a finer grain locking/quiesce to these 
operations?
An example would be that during mapping of volume V to host H1, host H2 
which is already mapped to V should not be affected. Another even more 
severe example would be if host H2 would have been mapped to volume V2 
which is not related to the new mapping.

Regards,
Shahar Salzman