Performance degradation of ZFS?

[Yasuhiro KIMURA]

From: Lars Liedtke <liedtke at punkt.de>
Subject: Re: Performance degradation of ZFS?
Date: Mon, 21 Jan 2019 13:18:58 +0100

> might your Pool run out of capacity? Note: ZFS performance goes down
> from about 85% to 90% upwards.

Though I can't remember exactly, capacity of pool was less than 40%
according to the output of 'zpool list zroot'.

From: Steve O'Hara-Smith <steve at sohara.org>
Subject: Re: Performance degradation of ZFS?
Date: Mon, 21 Jan 2019 12:35:24 +0000

> 	How is the pool configured ? How full is it ? How well is the data
> striped (are some vdevs fuller than others) ? Are any of the drives showing
> trouble ? Do you run a regular scrub ? What does zpool status show ?

I created old pool by using installer of 11.0-RELEASE with automatic
ZFS configuration. It used only 1 HDD and therefore wasn't striped at
all. AFAIK the drive didn't show any trouble. As for scrub I used
daily periodic jobs by setting 'daily_scrub_zfs_enable="YES"'. So pool
was scrubed every 35 days. And as far as I remember there was no case
that 'zpool status' showed scrub repaired any errors. Since I used
regular upgrade steps that are written in /usr/src/Makefile when
upgrading from 11.0 to 11.1 and from 11.1 and 11.2, I used same zroot
pool about 2 years and 2 months. And because I'm using same hardware
after clean install of 12.0-RELEASE, hardware is not the reason of
performance change.

---
Yasuhiro KIMURA