[Seaside] saving an image while serving

Sebastian Sastre sebastian at flowingconcept.com
Mon Apr 18 12:45:07 UTC 2011

Great story Janko

On Apr 18, 2011, at 6:33 AM, Janko Mivšek wrote:

> Hi guys,
> Let me support Nevin claims strongly with my the same experiences with
> image based persistency. Anyone just enough pragmatic and with a bit of
> probability calculus can soon discover, how right Nevin is.
> I know that from my experience, ok, with VisualWorks images, which
> snapshot every hour. One such sole image hosts 50+ sites and in last 8
> years without any loss of data. We have just few crashes (around 2-4 per
> year) because of DOS attacks, and that's all.
> It is true that there is 1 hour window to loose data and that we had
> luck loosing nothing during those few (mostly nightly) crashes, but when
> I compare that with horror stories of friends using, say MySql...
> Of course such image is backup every hour, every night - just plain
> usual safety measures therefore.
> Best regards
> Janko
> On 18. 04. 2011 00:21, Nevin Pratt wrote:
>> On 4/17/11 12:13 PM, Sebastian Sastre wrote:
>>> The only realistic way we see for that is by scaling horizontally.
>>> Many many worker images will do. And if people needs more, well... you
>>> simply add more.
>> True.  If you need more, that is.  But...
>> ...just how much data per second do you think you'll send down, say, a
>> T1 internet link, anyway?  And if your website keeps everything in
>> memory (because the image is all in memory), and does not need to do any
>> disk I/O, just how fast of a computer do you think you'll need to send
>> that much data per second down a T1 link to the internet?
>> Sheesh, a Mac Mini will overdrive a T1, as long as the Mac Mini doesn't
>> have to do any disk I/O to a database.
>> In my experience, the bottleneck is usually the pipe to the internet
>> (unless you are using Java interfaced to, say, Oracle, that is-- in
>> which case you *will* probably need a massive hardware infrastructure
>> behind that little old T1 internet pipe).
>> But otherwise, it is surprising how simple the hardware can be.
>> We get several thousand visitors every day, and about a million page
>> views a month.  And, we don't even have a T1-- just a little old 256K
>> pipe to the internet.  And, we run it on an old-generation Mac Mini--
>> about 3 generations old.  And, Alexa says 54% of the sites on the
>> internet are slower than ours.
>> And, our bottleneck is still the pipe to the internet.  Not the
>> hardware.  And not the software.
>> Go figure.
>> Nevin
> -- 
> Janko Mivšek
> Aida/Web
> Smalltalk Web Application Server
> http://www.aidaweb.si
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