[OpenAFS] limit amount of uncommitted cache manager data?

Adam Megacz megacz@cs.berkeley.edu
Mon, 24 Sep 2007 10:01:41 -0700

I've noticed that when writing really large files with something like
"cat .. | gzip > /afs/file" on a machine with a very large cache
manager cache, several hundred megabytes of data can accumulate
locally before being written back when close() is called.  In some
cases, this can lead to write() calls being quite fast, but the final
close() call takes an hour or more to return.  We (hcoop) would like
to avoid this situation if possible.

I assume that this amount of "unwritten" data cannot exceed the size
of the cache -- and I guess if this happens, the application is
blocked until enough StoreData's have happened to free up cache space.
Is there any way to get the CM to start this throttling earlier on?
Say, for example, when the amount of unwritten data reaches 50MB?
Unfortunately setting the cache size to 50MB is not an option -- this
machine performs other tasks as well.

  - a

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