Re: WAL & ZFS

I've read all the info I could find re running PG on ZFS: turn off full page writes, turn on lz4, tweak recordsize so as to take advantage of compression, etc. One thing I haven't seen is whether a separate volume for WAL would benefit from a larger recordsize. Or any other tweaks???

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Scott Ribe
scott_ribe@elevated-dev.com
https://www.linkedin.com/in/scottribe/

Phoronix has tested ZFS against Ext3, Ext4 and XFS. ZFS was consistently performing worse than all other file systems. Here is the test with Oracle:

https://blog.docbert.org/oracle-on-zfs/

Here are several articles that caution against ZFS:

https://forums.servethehome.com/index.php?threads/very-slow-zfs-raidz2-performance-on-truenas-12.33094/

https://serverfault.com/questions/791154/zfs-good-read-but-poor-write-speeds

https://www.phoronix.com/scan.php?page=article&item=ubuntu1910-ext4-zfs&num=3

And finally, this: https://storytime.ivysaur.me/posts/why-not-zfs/

I would consider Linux ZFS only for toy databases that do not hold any serious data.

-- 
Mladen Gogala
Database Consultant
Tel: (347) 321-1217
https://dbwhisperer.wordpress.com