[Beowulf] network filesystem

Joe Landman landman at scalableinformatics.com
Mon Mar 5 23:48:48 EST 2007


Mark Hahn wrote:
>> Our developers  had  that issue  of inconsistent  file system  view in 
>> RHEL
>> based systems, some of it is solved by disabling dir list caching, 
>> another
>> by using noac,
> 
> well, developers should be smart enough to know what FS they're using,
> and how it's intended to behave.  turning off AC is a nice option, but 
> smarter is to leave it on and not try to cause race conditions.

... or to catch them and fix them ...

> (I expect that such race-friendly behavior will fail on some other 
> non-NFS filesystems, though probably harder to trigger.)
> 
>> what the other was doing was writing simultaneously to  the
>> same file partitioned over several nodes, I told this is probably not the
>> right way to do file writing. apparently he used to do it in Sun 
>> Solaris and
>> it worked flawlessly.
> 
> I would spank any developer who said "but it works on platform X"!
> developers must be aware of the spec, not merely what they can get away 
> with somewhere, sometime.  of course, this is the thinking behind apps 
> having "supported" platforms - just a fancy way of saying
> "no, we don't know what standards-conformance we need, or how we violate 
> the standard, but here's a few places we haven't yet noticed any 
> bad-enough bugs".

*sigh*  If only we could "spank" them.  In ISV circles, there is a meme 
running about that Linux == RHEL*.  So they code everything to that, and 
not to the LSB.

Note:  this is one thing that the Windows folks sorta kinda do right. 
There is a "spec" to some degree, and everyone can kinda sorta write to 
it.

Then again, when you completely dominate something, you can dictate to 
users.  We have a long standing IE problem with rendering forms in 
tables, everyone else can do it right, and the code checks out as w3c 
compliant ... oh, never mind, not worth trying to get IE to talk standards.

Standards only work when all players follow them.  They also need to be 
simple enough to follow.  Making a standard impossible to follow helps 
no end user.



-- 

Joseph Landman, Ph.D
Founder and CEO
Scalable Informatics LLC,
email: landman at scalableinformatics.com
web  : http://www.scalableinformatics.com
phone: +1 734 786 8423
fax  : +1 734 786 8452 or +1 866 888 3112
cell : +1 734 612 4615

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