"Your mileage will vary" and "it depends" are always 100% accurate, but
that does not make them useful.
Its generally correct to advise testing, but benchmarking memory access
is a big task, and anyone holding a title like "architect" should expect
to substantiate.
On 3/31/17 13:52, Dimensional DBA wrote:
The information about going from 1600MHZ to 1066MHZ is in the Intel and HW documentation relative to Intel architecture.
I have benchmarked systems with a variety of different applications java, python, perl, databases etc.
The “your milage will vary” is of course very accurate. The performance differential to the app in some cases was very low and in other cases was up to 40% differential.
Depends on your app and what the app is doing.
*Matthew Parker*
*Chief Technologist*
*Dimensional DBA*
*425-891-7934 (cell)*
*D&B *047931344**
*CAGE *7J5S7**
*Dimensional.dba@xxxxxxxxxxx <mailto:Dimensional.dba@xxxxxxxxxxx>*
*View Matthew Parker's profile on LinkedIn* <http://www.linkedin.com/pub/matthew-parker/6/51b/944/>
www.dimensionaldba.com <http://www.dimensionaldba.com/>
*From:*Tim Gorman [mailto:tim.evdbt@xxxxxxxxx]
*Sent:* Friday, March 31, 2017 12:33 PM
*To:* Amir.Hameed@xxxxxxxxx; Dimensional DBA; 'ORACLE-L'
*Subject:* Re: Memory speed question
Amir,
I'd recommend pushing hard for concrete information: a KB or support documentation from Cisco. Lacking substantiation, it's just an opinion.
Don't allow hearsay, opinions, and myths to propagate without challenge. Be respectful, be polite, but be firm.
Hope this helps...
-Tim
On 3/31/17 13:08, Hameed, Amir wrote:
For that we will need to buy memory and then add it to the host
which is what we are trying to avoid. We have also asked our data
center to check with Cisco and the response we got was that
“mileage will vary”.
*From:* Dimensional DBA [mailto:dimensional.dba@xxxxxxxxxxx]
*Sent:* Friday, March 31, 2017 3:01 PM
*To:* Hameed, Amir <Amir.Hameed@xxxxxxxxx>
<mailto:Amir.Hameed@xxxxxxxxx>; 'ORACLE-L'
<oracle-l@xxxxxxxxxxxxx> <mailto:oracle-l@xxxxxxxxxxxxx>
*Subject:* RE: Memory speed question
It is simplest to run a benchmark and you will see that your app
will notice a difference if you have a low latency app.
It also limits the overall amount of work that can be accomplished
on that blade.
*Matthew Parker*
*Chief Technologist*
*Dimensional DBA*
*425-891-7934 (cell)*
*D&B *047931344
*CAGE *7J5S7
*Dimensional.dba@xxxxxxxxxxx <mailto:Dimensional.dba@xxxxxxxxxxx>*
*View Matthew Parker's profile on LinkedIn*
<http://www.linkedin.com/pub/matthew-parker/6/51b/944/>
www.dimensionaldba.com <http://www.dimensionaldba.com/>
*From:*oracle-l-bounce@xxxxxxxxxxxxx
<mailto:oracle-l-bounce@xxxxxxxxxxxxx>
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] *On Behalf Of *Hameed, Amir
*Sent:* Friday, March 31, 2017 11:55 AM
*To:* 'ORACLE-L'
*Subject:* Memory speed question
We have a four-node ESX farm/cluster where each node is loaded
with 512G of physical memory. These ESX nodes are Cisco UCS
blades. We are looking into adding more memory to each of these
ESX hosts to increase the footprint to 750G/node. One of the data
center architects had informed us last year that per Cisco, the
sweet-spot of memory footprint on these blades is 512GB, after
that the memory access speed would drop from 1600MHZ to 1066MHZ (a
drop of ~ 30%). Because all of our VMs host application tiers and
they run a lot of JVM processes, we are concerned that a drop of
30% will negatively impact our applications’ performance. However,
our data center has been telling us that the drop will not be
noticed by the application which I find hard to believe. We also
do not want to add another ESX host because of licensing cost.
I was wondering if anyone is running their ESX hosts with memory
over 512G/host and if they observed any issue with memory speed.
Thank you,
Amir
