Hello Dan, Tuesday, April 17, 2007, 10:59:53 PM, you wrote:
DM> Robert Milkowski wrote: >> Hello Dan, >> >> Tuesday, April 17, 2007, 9:44:45 PM, you wrote: >> >>>>> How can this work? With compressed data, its hard to predict its >>>>> final size before compression. >>>> Because you are NOT compressing the file only compressing the blocks as >>>> they get written to disk. >> >> DM> I guess this implies that the compression only can save integral numbers >> of >> DM> blocks. >> >> Can you clarify please? >> I don't understand above.... DM> If compression is done block-wise, then if I compress a 512-byte block to 2 DM> bytes, I still need a 512-byte block to store it. DM> Similarly, if I compress 1000 blocks to 999.001 blocks, I still need 1000 DM> blocks to store them. DM> This is not a significant problem, I'm sure, but it's worth remembering. DM> Many tiny files probably don't benefit from compression at all, rather than DM> "only a little". Yep, that's true. As smallest block in zfs is 512... But there's one exception - if you're creating small files (and also large one) fill with 0s then you will gain storage even if each file is less than 512B as no data block is allocated then :) -- Best regards, Robert mailto:[EMAIL PROTECTED] http://milek.blogspot.com _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
