Re: Lun size and performance with flash disks : rh7

Hello Mark, Stefan
Thank you.
The good approach is always test and compare. Have a nice weekend
Thierry

Le jeu. 25 juin 2020 à 15:10, Mark W. Farnham <mwf_at_rsiz.com> a écrit :

> +42 (Thanks Stephan, for keeping this clear.)
>
> AND this benchmark is important for any actual configuration: Even if some
> vendor expands the limits of a single bus to their SSD LUN beyond the speed
> (latency and bandwidth) of SSD or any future persistent memory, it is still
> very likely connected to something on the host computer that is much faster
> as multiple separate channels from the persistent memory into your computer
> RAM.
>
> The plumbing is complicated with many layers of competing latency and
> bandwidth. This is a good reason to think good thoughts about Kevin Closson
> for the end to end actual performance RESULT from the stack for Oracle via
> his SLOB.
>
> BORING is good, be a SLOBber.
>
> mwf
>
> -----Original Message-----
> From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org]
> On Behalf Of Stefan Koehler
> Sent: Thursday, June 25, 2020 6:30 AM
> To: tgascard_at_gmail.com; ORACLE-L
> Subject: Re: Lun size and performance with flash disks : rh7
>
> Hello Thierry,
> first counter question for storage vendor would be: Can you please provide
> a benchmark (with raw data if possible) that proves your statement?
>
> I mean it is always important to check what they are referring/comparing
> to. Comparing one SSD/Flash LUN to some old rusty spindle disks ... well
> yes ... in this case SSD/Flash might always be faster and you are happy
> anyway.
>
> However if you compare one SSD LUN vs. ten SSD LVM striped LUNs with +15K
> IOPS or so ... well then the picture is different.
>
> This topic is pretty easy to verify. Just run your workload (e.g. SLOB
> benchmark) on a file system backed by one big SSD LVM LUN and on file
> system backed by ten striped LVM SSD LUNs and monitor with iostat -xk 1
> <LUNs> .... you gonna see the difference for sure.
>
> Based on my experience with a lot of performance benchmarks - multiple
> striped (SSD) LUNs make an impact on systems with big I/O load :-)
>
> Best Regards
> Stefan Koehler
>
> Independent Oracle performance consultant and researcher
> Website: http://www.soocs.de
> Twitter: _at_OracleSK
>
> > thierry gascard <tgascard_at_gmail.com> hat am 25. Juni 2020 um 08:51
> geschrieben:
> >
> > Hello ,Storage vendors claim that we do not care anymore about io queue
> per lun on scsi.Two years ago I made test on ssd , and have multiple luns
> on data rather than a big one improve performance. Does anyone have
> feedback about it ?
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