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From: Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl>
To: Ivan Voras <ivoras@freebsd.org>
Subject: Re: iSCSI vs. SMB with ZFS.
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> With a network file system (either SMB or NFS, it doesn't matter), you
> need to ask the server for *each* of the following situations:
> 	* to ask the server if a file has been changed so the client can use
> cached data (if the protocol supports it)
> 	* to ask the server if a file (or a portion of a file) has been locked
> by another client

not really if there is only one user of file - then windows know this, but 
change to behaviour you described when there are more users.

AND FINALLY the latter behaviour fails to work properly since windows XP 
(worked fine with windows 98). If you use programs that read/write share 
same files you may be sure data corruption would happen.

you have to set
locking = yes
oplocks = no
level2 oplocks = no

to make it work properly but even more slow!.

> This basically means that for almost every single IO, you need to ask
> the server for something, which involves network traffic and round-trip
> delays.
Not that. The problem is that windows do not use all free memory for 
caching as with local or "local" (iSCSI) disk.