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

On 07/07/2021 00:01, Pete Wright wrote:

> 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
> command."
> 
> 
> 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?

I was thinking this too - the autotrim stuff came in with OpenZFS, but I 
had trim enabled previously (I believe we had our own implementation on 
FreeBSD ZFS, is that right?). But I am wondering if a schduled trim 
might be a better option. Though the question arises as to 'how often' 
in that case.

-pete.