[gpfsug-discuss] Compression details

[Shaun Anderson]

I've had the question come up about how SS will handle file deletion as well as overhead required for compression using zl4.


The two questions I'm looking for answers (or better yet, reference material documenting) to are:


1)

-    How is file deletion handled?


Is the block containing the compressed file decompressed, the file deleted, and then recompressed? Or is metadata simply updated showing the file is to be deleted? Does Scale run an implicit 'mmchattr --compression no' command?


2)

-    Are there any guidelines on the overhead to plan for in a compressed environment (lz4)?  I'm not seeing any kind of sizing guidance.  This is potentially going to be for an exisitng ESS GL2 system.


Any assistance or direction is appreciated.


Regards,

?
SHAUN ANDERSON
STORAGE ARCHITECT
O 208.577.2112
M 214.263.7014


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