And for some really ancient history (at least 10 years ago), I believe
this bit of documentation
actually resulted from one of the developers acidently running the set
of tests in their home directory on nfs and getting errors. So at least
at that time it didn't even take a crash to make something fail across nfs
vs local disk. I don't think we have done any testing on remote file
systems on purpose since then.
Kathey Marsden wrote:
I have always told users they have to have their databases on a local
disk to ensure data integrity and that a system crash for an NFS
mounted database could cause fatal corruption, but had a user this
morning take me to task on this and ask me to explain exactly why. I
gave my general response about not being able to guarantee a sync to
disk over the network, but want to have a more authoritative reference
for why you cannot count on an NFS mounted disk although I did find
several places where the sync option "favors data integrity" which
certainly doesn't sound like a guarantee. Does anyone know a good
general reference I can use on this topic to support my "you gotta use a
local disk" mantra.
Also I think our documentation on this topic should be a bit stronger.
Currently we just say it may not work and probably should be clearer
that data corruption could occur. I will file an issue to beef up the
language based on the conversation in this thread.
http://db.apache.org/derby/docs/10.5/devguide/cdevdvlp40350.html
Thanks
Kathey
