Re: Effect of using SATA 2.x and 3.x in zfs mirrored config

----- Original Message -----
> From: "Steve O'Hara-Smith" <steve@sohara.org>
> To: "Dale Scott (dalescott@shaw)" <dalescott@shaw.ca>
> Cc: "freebsd-questions" <freebsd-questions@freebsd.org>
> Sent: Thursday, June 2, 2022 3:07:32 PM
> Subject: Re: Effect of using SATA 2.x and 3.x in zfs mirrored config

> On Thu, 2 Jun 2022 07:34:51 -0600 (MDT)
> Dale Scott <dalescott@shaw.ca> wrote:
> 
>> Looking in dmesg, I see one of the drives is using SATA 3 (600MB/s
>> transfer), and the other is using SATA 2 (300MB/s transfer). Will mixing
>> SATA 2 and SATA 3 drives cause any technical issues? Is there any reason
>> why I should use SATA 2 for both drives?
> 
>	No reason at all to do so, but it probably wouldn't hurt either, I
> doubt the drives can exceed SATA 2 speeds for long if at all.
> 
>	ZFS won't know or care what underpins the devices. I've even
> mirrored a laptop SSD with an iSCSI accessed zvol on a NAS - it worked fine
> (I didn't try disaster recovery, that would take some thinking about) the
> main aim was to make a weekly scrub worthwhile.
> 
> --
> Steve O'Hara-Smith <steve@sohara.org>


Thanks for vote of confidence in ZFS. Since JBOD works I wasn't expecting trouble, but it was still a surprise to learn the drives were using different protocols. My larger concern was, if there was a reason why using the same protocol was "better", whether moving the SATA cable to a different port would trigger issues with ZFS, and I would need to learn much more about ZFS than I do now. 

Cheers,
Dale