Persistence vs SH scheduler

[Joseph Mack NA3T]

On Fri, 2 Jun 2006, Martijn Grendelman wrote:

> Hi,
>
> I was justing browsing the HOWTO, when I stumbled upon this recent piece of 
> text:
>
>
> Apr 2006: No-one has tried this, but it seems that the -SH scheduler could 
> replace persistence without the failover problems of persistence. The -SH 
> scheduler schedules according to the client IP, meaning that all of a 
> client's connection requests will be sent to the same IP. The -SH scheduler 
> has been around for a while, but it seems that no-one has known what it did.

It's nice to know that someone reads the HOWTO :-)

> When I first started to toy around with LVS, I did just what is written here: 
> i tried to use the SH scheduler for "session affinity" at L7.
>
> However, I had problems, that I posted to this list:
>
> http://www.in-addr.de/pipermail/lvs-users/2004-March/011171.html

when I realised that I didn't know what the SH scheduler 
did, I looked through all the postings with "SH" and 
"scheduler" to find that no-one else knew a whole lot 
either.

hmm - It seems that the packets get scrambled ocassionally,
presumably a consequence of the code having never been 
tested.

> I never found a solution, and I finally decided that SH wasn't going to work, 
> and I set up an Msession server for "session clustering" and used the RR 
> scheduler. This setup works perfectly and is still in use today.
>
> However, since Msession is hopelessly outdated, and its successor (Mcache) 
> doesn't seem to get off the ground, and I haven't found any workable (open 
> source) alternatives, I would really like have another look at LVS 
> persistence of some sort.
>
> The question is: has anything changed in the SH scheduler in the past two 
> years, that could possibly have fixed the problems I ran into? I suspect, 
> since only No-one has tried using it, there's not a big chance of that ;-)

AFAIK, nothing has happened to the SH scheduler since the 
day it was released. Unless you want to spelunk the code to 
find out what's going on, the SH scheduler is basically 
unsupported and apparently not ready for production.

Sorry

Joe

-- 
Joseph Mack NA3T EME(B,D), FM05lw North Carolina
jmack (at) wm7d (dot) net - azimuthal equidistant map
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