Samsung 840 Pro SSD and quirks

[Jason Wolfe]

We run the Samsung 843T drives, which are basically 840s with extra flash
for over provisioning.  We have directly from Samsung that they are in fact
4k drives, which led to the quirk addition for the 843T in r270305.
 Anyway, just wanted to round the thread out with some confirmation.

Jason

On Tue, Sep 2, 2014 at 8:07 AM, Steven Hartland <killing at multiplay.co.uk>
wrote:

> Thanks for the confirmation Borja I was a little confused why
> our two results differed.
>
> For a 12 disk system you'll likely need two SAS2 controllers,
> or at least 12 SAS lines otherwise you will hit controller
> throughput issues as a 840 can pretty much saturate a single
> SAS2 lane on its own.
>
> At that point you'll also start to see other issues.
>
> I'd strongly suggest moving to stable/10, if you haven't already,
> particularly if you have large amount of RAM in the system
> otherwise you will become CPU bound on ARC hash lookups.
>
>    Regards
>    Steve
>
> ----- Original Message ----- From: "Borja Marcos" <borjam at sarenet.es>
> To: "Steven Hartland" <killing at multiplay.co.uk>
> Cc: "FreeBSD-scsi" <freebsd-scsi at freebsd.org>
> Sent: Tuesday, September 02, 2014 3:48 PM
> Subject: Re: Samsung 840 Pro SSD and quirks
>
>
>
>
> On Sep 1, 2014, at 5:44 PM, Steven Hartland wrote:
>
>  We saw a noticable performance increase on 4k on our 8TB 840
>> array but I too couldn't find any concrete information either.
>>
>> If anyone has this info and can confirm either way that would
>> be great.
>>
>
> I stand corrected. I have done some benchmarks with just two Samsung SSDs
> (zpool with two disks, no mirroring) and indeed I get better performance
> with 4 KB blocks.
>
> I did my original tests with 12 disks and some other bottleneck was hiding
> the performance difference.
>
> In both cases, anyway, Trim was working unless the system lies.
>
>
>
>
>
> Thanks!
>
>
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