[zfs-discuss] ZFS over multiple iSCSI targets

[James Andrewartha]

Tuomas Leikola wrote:
> On Mon, Sep 8, 2008 at 8:35 PM, Miles Nordin <carton at ivy.net> wrote:
>>    ps> iSCSI with respect to write barriers?
>>
>> +1.
>>
>> Does anyone even know of a good way to actually test it?  So far it
>> seems the only way to know if your OS is breaking write barriers is to
>> trade gossip and guess.
> 
> Write a program that writes backwards (every other block to avoid
> write merges) with and without O_DSYNC, measure speed.
> 
> I think you can also deduce driver and drive cache flush correctness
> by calculating the best theoretical correct speed (which should be
> really slow, one write per disc spin)
> 
> this has been on my TODO list for ages.. :(

Does the perl script at http://brad.livejournal.com/2116715.html do what you
want?

-- 
James Andrewartha