I copied the same 478 mp3 files of 2–7MiB each (for a total of 1940MiB) to datasets with different recordsizes and compression set:
I don't understand why larger recordsizes show more logicalreferenced space, and why that "overhead" (for lack of a better term) gets compressed away by even zle compression.
The best I can think of is "partial-record overhead", where 800K worth of data in a 1M record would waste 200K on zeroes. But all documentation says that this never happens, because partial records are stored truncated (down to ashift granularity).
So what's happening here?!
Code:
NAME RECSIZE REFER LREFER COMPRESS
safe/test/none-1M 1M 2.09G 2.09G off
safe/test/zle-1M 1M 1.87G 2.09G zle
safe/test/lz4-1M 1M 1.86G 2.09G lz4
safe/test/none-512K 512K 1.98G 1.98G off
safe/test/lz4-512K 512K 1.86G 1.98G lz4
safe/test/none-64K 64K 1.88G 1.88G off
safe/test/lz4-64K 64K 1.85G 1.88G lz4
safe/test/none-4K 4K 1.90G 1.88G off
safe/test/lz4-4K 4K 1.89G 1.88G lz4
The best I can think of is "partial-record overhead", where 800K worth of data in a 1M record would waste 200K on zeroes. But all documentation says that this never happens, because partial records are stored truncated (down to ashift granularity).
So what's happening here?!