[Beowulf] NFS over RDMA performance confusion

Ellis H. Wilson III ellis at cse.psu.edu
Thu Sep 13 06:42:17 PDT 2012


On 09/13/2012 09:23 AM, Vincent Diepeveen wrote:
> On Sep 13, 2012, at 3:02 PM, Ellis H. Wilson III wrote:
>> On 09/13/2012 08:52 AM, Vincent Diepeveen wrote:
>>> the actual data goes through RDMA here and maybe through TCP using
>>> mysql.
>>
>> I'm almost certain this isn't going through mysql, or this is an
>> incredibly strange version of IOzone.  This is just "mimicking"
>> database
>> accesses by doing smallish record direct I/O.
>>
>> Am I correct in my thinking here?
>
> from email some time ago posted on this list:
>
> " Oracle and
> Nexenta are both sending me ZFS based boxes to test and I hope to
> compare
> the performance and stability of these with the Netapp (formally lsi
> engenio) E540"
>
> He got one or more machines from Oracle and the dude is benchmarking
> MySQL...

I'll wait for somebody with IOzone expertise to speak to this, but I'm 
99% sure IOzone cannot push data through any SQL implementation.  It's 
just a raw I/O benchmark to my knowledge.  Maybe there is some esoteric 
way to force everything through SQL, but I'm unaware of that so this is 
why I asked if I was correct in my understanding of IOzone.

Nevertheless, I recognize and agree he is attempting to get a feel for 
how MySQL is going to perform storage-wise by doing this, and that's 
totally fine as a first pass, but I do not think this is going through 
MySQL, which makes your concerns about things being pushed over TCP/IP 
not yet tenable.

Best,

ellis


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