another question about zfs compression numbers

Patrick M. Hausen hausen at
Wed Apr 4 07:41:00 UTC 2018

Hi all,

> Am 04.04.2018 um 09:21 schrieb Eugene M. Zheganin <eugene at>:
> I'm just trying to understand these numbers:
> file size is 232G, it's actual size on the lz4-compressed dataset is 18G, so then why is the compressratio only 1.86x ? And why logicalused is 34.2G ? On one hand, 34.2G exactlyfits to the 1.86x compresstaio, but still I don't get it. dataset is on raidz, 3 spans across 5 disk vdevs, with total of 15 disks if it matters:

A sparse file, possibly? The ZFS numbers refer to blocks. "Skipping" zeroes at the
VFS layer is not taken into account as fas as I know. Seriously, how should it?
If I'm not mistaken, ZFS will never get to see these empty blocks.

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