[CentOS] openfiler (was: using CentOS as an iSCSI server?)

Clint Dilks clintd at scms.waikato.ac.nz
Tue Oct 20 22:28:10 UTC 2009


John R Pierce wrote:
> absolutely CRITICAL to any SAN implementations is that the storage 
> controller (iscsi target, be it openfiler or what) remain 100% rock 
> solid tsable at all times.
>
> you can NOT REboot a shared storage controller without shutting all 
> client  systems down first (or at least unmounting all SAN volumes)
>
> its non-trivial to implement a high availability  (active/standby) 
> storage controller with iscsi.    very hard, in fact. 
>
>   
Dell have recently announced a product that may help a lot with this 
they call it Virtualized ISCSI devices see 
http://www.cns-service.com/equallogic/pdfs/WP910_Virtualized_iSCSI_SANs.pdf

> commercial SANs are fully redundant, with redundant fiberchannel cards 
> on each client and storage controller, redundant fiberchannel switches, 
> redundant paths from the storage controllers to the actual drive arrays, 
> etc.   many of them shadow the writeback cache storage so if one 
> controller fails the other one has any write cached blocks and can post 
> them to the disk spindles transparently to maintain complete data 
> coherency.    Trying to achieve this level of 0.99999 uptime/reliability 
> with commodity hardware and software is not easy.
>
>
>
>
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>   



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