RE: Lun size and performance with flash disks : rh7

+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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