openstack team mailing list archive

[Chander Kant <ck@xxxxxxxxxx>]

On Wed, Oct 24, 2012 at 4:19 PM, Sina Sadeghi <sina@xxxxxxxxxx> wrote:

>  The guys from Zmanda presented some evaluation of swift at the summit,
> might be useful here
>
> http://www.zmanda.com/blogs/?p=947 they've written a blog but it doesn't
> have all the findings which they presented at the summit.
>
> Maybe Chander would be willing to share? I've CC'd him in.
>


Sure. We have published a new blog related to the summit, including a link
to our presentation slides:

http://www.zmanda.com/blogs/?p=971
http://www.zmanda.com/pdf/how-swift-is-your-Swift-SD.pdf

We plan to publish more performance results within next few weeks.

-Chander





>
> --
> *Sina Sadeghi*
> Lead Cloud Engineer
>
> *Aptira Pty Ltd*
> 1800 APTIRA
> aptira.com <http://www.aptira.com>
> Follow @aptira <https://twitter.com/#/aptira>
>
>  On 25/10/12 08:03, Alejandro Comisario wrote:
>
> Wow nice, i think we have a lot to look at guys.
> I'll get back to you as soon as we have more metrics to share regarding
> this matter.
> Basically, we are going to try to add more proxies, since indeed, the
> requests are to small (20K not 20MB)
>
>  Thanks guys !
> -----------
> Alejandrito
>
>   On Wed, Oct 24, 2012 at 5:49 PM, John Dickinson <me@xxxxxx> wrote:
>
>> Smaller requests, of course, will have a higher percentage overhead for
>> each request, so you will need more proxies for many small requests than
>> the same number of larger requests (all other factors being equal).
>>
>> If most of the requests are reads, then you probably won't have to worry
>> about keystone keeping up.
>>
>> You may want to look at tuning the object server config variable
>> "keep_cache_size". This variable is the maximum size of an object to keep
>> in the buffer cache for publicly requested objects. So if you tuned it to
>> be 20K (20971520)--by default it is 5424880--you should be able to serve
>> most of your requests without needing to do a disk seek, assuming you have
>> enough RAM on the object servers. Note that background processes on the
>> object servers end up using the cache for storing the filesystem inodes, so
>> lots of RAM will be a very good thing in your use case. Of course, the
>> usefulness of this caching is dependent on how frequently a given object is
>> accessed. You may consider an external caching system (anything from
>> varnish or squid to a CDN provider) if the direct public access becomes too
>> expensive.
>>
>> One other factor to consider is that since swift stores 3 replicas of the
>> data, there are 3 servers that can serve a request for a given object,
>> regardless of how many storage nodes you have. This means that if all 3500
>> req/sec are to the same object, only 3 object servers are handling that.
>> However, if the 3500 req/sec are spread over many objects, the full cluster
>> will be utilized. Some of us have talked about how to improve swift's
>> performance for concurrent access to a single object, but those
>> improvements have not been coded yet.
>>
>> --John
>>
>>
>>
>> On Oct 24, 2012, at 1:20 PM, Alejandro Comisario <
>> alejandro.comisario@xxxxxxxxxxxxxxxx> wrote:
>>
>> > Thanks Josh, and Thanks John.
>> > I know it was an exciting Summit! Congrats to everyone !
>> >
>> > John, let me give you extra data and something that i've already said,
>> that might me wrong.
>> >
>> > First, the request size that will compose the 90.000RPM - 200.000 RPM
>> will be from 90% 20K objects, and 10% 150/200K objects.
>> > Second, all the "GET" requests, are going to be "public", configured
>> through ACL, so, if the GET requests are public (so, no X-Auth-Token is
>> passed) why should i be worried about the keystone middleware ?
>> >
>> > Just to clarify, because i really want to understand what my real
>> metrics are so i can know where to tune in case i need to.
>> > Thanks !
>> >
>> > ---
>> > Alejandrito
>> >
>> >
>> > On Wed, Oct 24, 2012 at 3:28 PM, John Dickinson <me@xxxxxx> wrote:
>> > Sorry for the delay. You've got an interesting problem, and we were all
>> quite busy last week with the summit.
>> >
>> > First, the standard caveat: Your performance is going to be highly
>> dependent on your particular workload and your particular hardware
>> deployment. 3500 req/sec in two different deployments may be very different
>> based on the size of the requests, the spread of the data requested, and
>> the type of requests. Your experience may vary, etc, etc.
>> >
>> > However, for an attempt to answer your question...
>> >
>> > 6 proxies for 3500 req/sec doesn't sound unreasonable. It's in line
>> with other numbers I've seen from people and what I've seen from other
>> large scale deployments. You are basically looking at about 600
>> req/sec/proxy.
>> >
>> > My first concern is not the swift workload, but how keystone handles
>> the authentication of the tokens. A quick glance at the keystone source
>> seems to indicate that keystone's auth_token middleware is using a standard
>> memcached module that may not play well with concurrent connections in
>> eventlet. Specifically, sockets cannot be reused concurrently by different
>> greenthreads. You may find that the token validation in the auth_token
>> middleware fails under any sort of load. This would need to be verified by
>> your testing or an examination of the memcache module being used. An
>> alternative would be to look at the way swift implements it's memcache
>> connections in an eventlet-friendly way (see
>> swift/common/memcache.py:_get_conns() in the swift codebase).
>> >
>> > --John
>> >
>> >
>> >
>> > On Oct 11, 2012, at 4:28 PM, Alejandro Comisario <
>> alejandro.comisario@xxxxxxxxxxxxxxxx> wrote:
>> >
>> > > Hi Stackers !
>> > > This is the thing, today we have a 24 datanodes (3 copies, 90TB
>> usables) each datanode has 2 intel hexacores CPU with HT and 96GB of RAM,
>> and 6 Proxies with the same hardware configuration, using swift 1.4.8 with
>> keystone.
>> > > Regarding the networking, each proxy / datanodes has a dual 1Gb nic,
>> bonded in LACP mode 4, each of the proxies are behind an F5 BigIP Load
>> Balancer ( so, no worries over there ).
>> > >
>> > > Today, we are receiving 5000 RPM ( Requests per Minute ) with 660 RPM
>> per Proxies, i know its low, but now ... with a new product migration, soon
>> ( really soon ) we are expecting to receive about a total of 90.000 RPM
>> average ( 1500 req / s ) with weekly peaks of 200.000 RPM ( 3500 req / s )
>> to the swift api, witch will be 90% public gets ( no keystone auth ) and
>> 10% authorized PUTS (keystone in the middle, worth to know that we have a
>> 10 keystone vms pool, connected to a 5 nodes galera mysql cluster, so no
>> worries there either )
>> > >
>> > > So, 3500 req/s divided by 6 proxy nodes doesnt sounds too much, but
>> well, its a number that we cant ignore.
>> > > What do you think about this numbers? does this 6 proxies sounds
>> good, or we should double or triple the proxies ? Does anyone has this size
>> of requests and can share their configs ?
>> > >
>> > > Thanks a lot, hoping to ear from you guys !
>> > >
>> > > -----
>> > > alejandrito
>> > > _______________________________________________
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>> >
>>
>>
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