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

John R Pierce pierce at hogranch.com
Tue Oct 20 23:04:49 UTC 2009


nate wrote:
> Network RAID – only available from HP
>   

Fantasy ideas (eg, I've only thought of this and never tried it). YMMV, 
caveat emptor, objects in mirror may be closer than they appear, etc etc.

1) two ISCSI servers, each with identical storage. each offers the same 
sized iscsi target to the host. the host uses mdraid 1 to mirror these.

2) two ISCSI servers, each with identical storage, configured as 
active-standby cluster, using conventional cluster management software. 
active 'master' replicates block storage to 'slave' using DRBD.



with 1) there's questions of how well the mdraid will recover from 
situations where one storage server is offline for some period. I'd feel 
much warmer about this if there was block checksumming and time stamping 
in the raid ala ZFS.

with 2) there's write fencing issues I'd be uncomfortable with, on a 
fenced write, you'd not want to acknowlege operation committed until the 
drbd slave has flushed its buffers.





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