[OpenAFS-devel] Large-Cache Initialization (Proposal)

[Sam Hartman]

>>>>> "Derek" == Derek Atkins <warlord@MIT.EDU> writes:

    Derek> "Patrick J. LoPresti" <patl@curl.com> writes:
    >> 1) What Linux kernel do you recommend for file servers?  I am
    >> interested in stability first, performance second.  The options
    >> are 2.2.x versus 2.4.x, and SMP versus non-SMP.  (I know,
    >> perhaps Solaris would be a better choice.  But I need to work
    >> within our existing infrastructure.)

    Derek> For a _server_ I would recommend Linux 2.2.x SMP, although
    Derek> quite honestly it probably doesn't matter that much.  The
    Derek> Linux servers are all user-space.

    >> 2) If I want to create a 1G or 2G cache on the clients, is
    >> there any reasonable way to do it right now (e.g., increasing
    >> the chunk size or whatever it's called)?  If not, what is the
    >> largest reasonable cache size for Linux systems?

    Derek> Um, good question.  I don't know.  I tried to build a 3G
    Derek> cache and got frustrated.  If you're willing to let it sit
    Derek> for a long period of time, it should eventually complete
    Derek> the task of initializing the cache.  Future reboots should
    Derek> be much faster than the first-time cache creation (you're
    Derek> not performing N creat(2) operations in the same
    Derek> directory).  So, basically, start AFS with as big a cache
    Derek> as you want, but be willing to have your machine totally
    Derek> dedicated to the task of cache-initialization for a day or
    Derek> more.

Increasing the chunksize will certainly help.  Try a chunksize of say
20 (1m chunks) or so if you have lots of large files.  If you have
lots of small files, it is not clear we have a solution until Derek
finishes his work.