[gpfsug-discuss] AFM with clones

[Simon Thompson (IT Research Support)]

Hi,

We are looking at providing an AFM cache of a home which has a number of cloned files. From the docs:
https://www.ibm.com/support/knowledgecenter/en/STXKQY_5.0.0/com.ibm.spectrum.scale.v5r00.doc/bl1ins_afmandafmdrlimitations.htm

·         We can see that “The mmclone command is not supported on AFM cache and AFM DR primary filesets. Clones created at home for AFM filesets are treated as separate files in the cache.”

So it’s no surprise that when we pre-cache the files, they space consumed is different.

What I’m not clear on is what happens if we update a clone file at home? I know AFM is supposed to only transfer the exact bytes updated, does this work with clones? i.e. at home do we just get the bytes updated in the copy-on-write clone, or do we accidentally end up shipping the whole file back?

(note we are using IW mode)

Thanks

Simon
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