On 4 Feb 2010, at 16:35, Bob Friesenhahn wrote:
> On Thu, 4 Feb 2010, Darren J Moffat wrote:
>>> Thanks - IBM basically haven't test clearcase with ZFS compression
therefore, they don't support currently. Future may change, as such my customer cannot
use compression. I have asked IBM for roadmap info to find whether/when it will be
supported.
>>
>> That is FUD generation in my opinion and being overly cautious. The whole
point of the POSIX interfaces to a filesystem is that applications don't actually
care how the filesystem stores their data.
>
> Clearcase itself implements a versioning filesystem so perhaps it is not
being overly cautious. Compression could change aspects such as how free space is
reported.
I'd also like to echo Bob's observations here. Darren's FUDFUD is
> based on limited experience of ClearCase, I expect ...
I do know how ClearCase works and it works *above* the POSIX layer in
ZFS - at the VFS layer (and higher). [I've debugged Solaris crash dumps
with the clear case kernel modules loaded in them in the past].
By FUD I don't mean it is wrong, but without information about a bug or
observed undesirable behaviour it is coming across as Fear that there
could be problems. Basically we need more data.
What I was pointing out is that because of the layer that ClearCase
works there should be no problems - I'm not saying there aren't any just
that I don't see where they would be.
If there are problems with ZFS then bugs should be logged, leaving
statements like "ISV x doesn't support using feature f of ZFS" is harm
full to the ISV's product and to ZFS when there is no bug logged or data
about why there is a problem.
--
Darren J Moffat
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