Re: ZFS + mysql appears to be killing my SSD's

From: Pete Wright via freebsd-stable <>
Date: Tue, 06 Jul 2021 23:01:25 UTC

On 7/5/21 7:51 AM, Alan Somers wrote:
> If you're using 4K sectors anyway, then GELI does not create any extra
> write amplification.   But if you're extra paranoid and you use the "-T"
> option to "geli attach", then GELI will block TRIM commands.  That could
> hurt SSD lifetime.  But I don't think "-T" is the default.  You are using
> 4K sectors, right?  ZFS's ashift is set to 12?
> -Alan

i also wonder if this could be a TRIM related issue.  according to 
zpoolprops(8) TRIM is not enabled by default on pools - but it also has 
this note (see autotrim):

"Be aware that automatic trimming of recently freed data blocks
can put significant stress on the underlying storage devices.
This will vary depending of how well the specific device handles
these commands.  For lower end devices it is often possible to
achieve most of the benefits of automatic trimming by running an
on-demand (manual) TRIM periodically using the zpool trim

I wonder if adjusting the autotrim feature will address these issues - i 
manually enable autotrim for my pools and have seen no bad effects under 
quite of bit of bursty i/o.  if it is enabled i wonder if the ssd you 
are using doesn't play nice with autotrim and should stay disabled?


Pete Wright