The fragmentation info does not describe the fragmentation of the data
on pool but the fragmentation of the free space. A high fragmentation
value will result in high data fragmentation only when you write or
modify data.
https://utcc.utoronto.ca/~cks/space/blog/solaris/ZFSZpoolFragmentationMeaning
So the best and only way to reduce data fragmentation is not to fill up
a pool say over 70-80%.
You should also know that CopyOnWrite filesystems where a complete
datablock ex 128k is written newly even if you change a "house" to a
"mouse" in a textfile are more vulnerable to fragmentation than older
filesystems. This is the price for the crash resitency where a power
outage during a write cannot lead to a corrupted filesystem like with
older filesystems where it can happen that the data is modified "infile"
while the according metadata update is not happening. ZFS
over-compensates this with its advanced rambased read and write caches.
A "defrag tool" is not available for ZFS.
Gea
Am 23.06.2017 um 16:13 schrieb Artyom Zhandarovsky:
there any way to decrease fragmentation of dr_tank ?
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