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Hi Huatao,
huatao wrote:
>
> Hello lvs-users,
> It's my first time to write to this list, nice to meet you all!
> I've got some questions:
> One is when failover takes place, will the requests during the failover
> course lose?
Yes, unfortunately. And this is very nasty for persistent setups
in an e-commerce environment. Take for example a simple e-com site
providing some subjects to buy. You can browse and view all their
goodies. At a certain point you want to buy something. Ok, it is
common nowadays that people can buy over the Internet with CC. Obviously
this is done f.e. with SSL. SSL needs persistency enabled in the
lvs-configuration. Imaging having 1000 users (conn ESTABLISHED)
that are entering their VISA information when the database server
crashes and the healthcheck takes out the server; or even more simple
when the server/service itself crashes. Ok, all already established
connections (they have a persistent template in the kernel space)
are lost and these 1000 users have to reauthenticate. How does this
look from a clients point of view which has no idea about the technology
behind a certain site.
To summarize: Yes, you loose the information in the kernel space about
the templates. Good thing: The design for a possible synchronisation
of the masqerading table from one director to another one is done the
implementation not.
> The other is how to benchmark failover, that is how long the services
> provided by LVS will be unavailable during the failover course.
This is up to different things: Your failover software used, the switch
setup and learning delay (extremely stupid feature of cisco switches) and
your setup.
HTH and best regards,
Roberto Nibali, ratz
--
mailto: `echo NrOatSz@xxxxxxxxx | sed 's/[NOSPAM]//g'`
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