Back in February of this year, there was a thread on this list
entitled "Open files disappear", which detailed I/O errors reported by
the 'blogbench' benchmark when running on AFS. The archive is at https://lists.openafs.org/pipermail/openafs-info/2009-February/030928.html
I discovered a similar problem yesterday, whilst testing some
modifications to the cache manager. After a fair amount of sleuthing
(blow by blow details in the [email protected] chatroom),
a group of us managed to get to the bottom of this. What is happening
is that blogbench is renaming a file on top of a file which it already
has open, which causes the fileserver to remove the open file. When we
do a normal remove of a file which is still open, AFS's silly-rename
support moves it to one side until all of the processes on the local
machine have closed the file. Silly rename hasn't been implemented for
files which get clobbered by a rename, hence the errors.
Whether the rename occurs whilst files are still open seems to be down
to a timing issue in the benchmark itself - the faster the machine, or
the larger the number of available processors, the more likely this is
to occur.
RT #124973 is tracking this issue - my intention is to implement the
missing silly rename support.
Cheers,
Simon.
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