Re: IO performance
- From: Mladen Gogala <gogala.mladen@xxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Sat, 24 Oct 2015 15:02:52 -0400
On 10/24/2015 02:23 AM, Cee Pee wrote:
Hi
I have a clarification about the IO performance. Let's say we find
that the IO performance is sub par at certain times in a day from
performance charts. With the storage all in one big SAN these days,
how do people really improve the IO performance. I would think that IO
characteristics of a SAN is 'uniform', so what would be the options to
improve IO performance.
CP.
Well, you can always get a bigger SAN. There are monsters out there in
the SAN world which offer so huge IO capacity that it would be very hard
to saturate them. An example is EMC (Dell?) XtremIO all-flash SAN. Also,
there are boxes which can be smart and use algorithm called "Bloom
filter" to eliminate the blocks that are definitely not needed to
satisfy your query, thereby greatly reducing the work that CPU has to do
in order to return the query rows. This system has "storage nodes" which
employ the Bloom filter technique and return the reduced data to the
"compute nodes". In its latest incarnation (X5-2), those machines can
be concatenated to a single logical server, thereby building gigantic
databases. X5-2 can also optionally be all-flash. Pythian measured it to
be capable of 263 GB/sec IO speeds:
http://www.pythian.com/blog/exadata-x5-a-practical-point-of-view-of-the-new-hardware-and-licensing/
Bottom line: there is a price tag for the IO throughput. The more IOPS
your storage can do, the more it costs. At the very top of the food
chain are monsters like XtremIO or Exadata X5. The next level down are
high end Hitachi VSP and EMC VMAX (formerly "Symmetrix") as well as the
high end IBM XIV arrays, all the way to cheapo NAS storage at the
bottom end, which typically supports CIFS and NFSv4 and no FC
connections, with all SAS disks, typically 10k RPM. IO tuning is
typically done with a check book. Between those two extreme ends, there
is a whole world of SAN devices like NetApp, 3Par and VNX, which offer
different levels of IO performance, depending on the model and price.
--
Mladen Gogala
Oracle DBA
http://mgogala.freehostia.com
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