[gpfsug-discuss] AFM prefetch and eviction policy question
Chris Kempin
quixote at us.ibm.com
Fri Jun 21 13:06:35 BST 2019
Ryan:
1) You will need to just regularly run a prefetch to bring over the latest
files .. you could either just run it regularly on the cache ( probably
using the --directory flag to scan the whole fileset for uncached files )
or, with a little bit of scripting, you might be able to drive the
prefetch from home if you know what files have been created/changed by
shipping over to the cache a list of files to prefetch and have something
prefetch that list when it arrives.
2) As to eviction, just set afmEnableAutoEviction=no and don't evict. is
there a storage constraint on the cache that would force you to evict?
I was using AFM in a more interactive application, with many small files
and performance was not an issue in terms of "fast" access to files, but
things to consider
What is the network latency between home and cache?
How big are the files you are dealing with? If you have very large files,
you may want multiple gateways so they can fetch in parallel.
How much change is there in the files?
How many new/changed files a day are we talking about?
Are existing files fairly stable?
Regards,
Chris
Chris Kempin
IBM Cloud - Site Reliability Engineering
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://gpfsug.org/pipermail/gpfsug-discuss_gpfsug.org/attachments/20190621/54fc70d0/attachment-0002.htm>
More information about the gpfsug-discuss
mailing list