Hi all,

Ok, this might be to stir some things up again but I would like to make this more clear.
I have been reading this and other threads regarding ZFS on SAN and  
how well ZFS can recover from a serious error such as a cached disk  
array goes down or the connection to the SAN is lost. What I am  
hearing (Miles, ZFS-8000-72) is that sometimes you can end up in an  
unrecoverable state that forces you to restore the whole pool. I have  
been operating quite large deployments of SVM/UFS VxFS/VxVM for some  
years and while you sometimes are forced to do a filesystem check and  
some files might end up in lost+found I have never lost a whole  
filesystem. This is despite whole arrays crashing, split-brain  
scenarios etc. In the previous discussion a lot of fingers was pointed  
at hardware and USB connections, but then some people mentioned  
loosing pools located SAN in this thread.
We are currently evaluating if we should begin to implement ZFS in our  
SAN. I can see great opportunities with ZFS but if we have a higher  
risk of loosing entire pools that is a serious issue. I am aware that  
the other filesystems might not be in a correct state after a serious  
failure, but as stated before  that can be much better than restoring   
a multi terabyte filesystem from yesterdays backup.
So, what is the opinion, is this an existing problem even when using  
enterprise arrays? If I understand this correctly there should be no  
risk of loosing an entire pool if DKIOCFLUSHWRITECACHE is honored by  
the array?
If it is a problem, will the worst case scenario be at least on pair  
with UFS/VxFS when 6667683 is fixed?
Grateful for any additional information.

Regards

Henrik Johansson
http://sparcv9.blogspot.com
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