[Opensim-users] Urban legends (Was :Configuring a multi-hosted grid)

[Thomas Ringate]

Melanie,

If I understand you correctly, sharing the cache between the three servers 
that are on OSgrid does not present any issue.  I could contaminate the 
cache if I copy it from my standalone grid back into the shared cache of the 
three OSgrid servers.  Do I understand that correctly?

Tom



-----Original Message----- 
From: Melanie
Sent: Friday, August 22, 2014 7:57 PM
To: opensim-users at opensimulator.org
Subject: Re: [Opensim-users] Urban legends (Was :Configuring a multi-hosted 
grid)

You can share cache between simulators that use the same central
services, for instance any simulators you use that are on OSGrid.
Don't share caches between services, as the asset ids are not valid
between services and you may wind up creating items that work only
on your own sims and from users' caches, but fail visually in
mysterious ways when taken off-sim.

There is some (yellow) spew occasionally, it's trivial to catch and
prevent in code, if you're so inclined. We have been ignoring it
ever since the cache was written, with no ill effects.

Melanie

On 23/08/2014 01:51, Thomas Ringate wrote:
> I've been running a shared cache now for a couple of years.  I even copy
> them in a round robin fashion between my four servers so they are nearly
> identical.  I turned off the clean up so anything that has been put in 
> them
> for about the last 10 months is still there.
>
> As you can tell I do not have a clue how the cache is used or how it 
> really
> works.  Since every item in is it indexed using the UUID and the first 
> three
> digits of the UUID place them in individual folders, I have not noticed 
> any
> folder being all that large.
>
> The reason I do this is because three of my servers are on OSgrid, the
> fourth is where I do my scripting using two standalones which are mirror
> images of the 64 regions I host on OSgrid.  One standalone is a normal set
> of regions and the other is a single varregion.
>
> I found I had much better success of having things appear on my 
> standalones
> once I consolidated all of the caches, but it is still far from being
> optimal.
>
> Now I am wondering if doing this is causing a performance hit on the three
> servers that host regions for OSgrid???
> What do the experts think?
>
> I could merge those cache into the one on the standalone server and have 
> one
> master region clean each servers cache to some appropriate level.  I like
> the idea of a shared cache on each server.  It eliminates redundancy and
> eliminates requests by different regions for the same object.
>
> I was surprised to hear it is not used for assets.  Why is it named
> "asset-cache"?
>
>
> -----Original Message----- 
> From: Justin Clark-Casey
> Sent: Friday, August 22, 2014 6:54 PM
> To: opensim-users at opensimulator.org
> Subject: Re: [Opensim-users] Urban legends (Was :Configuring a 
> multi-hosted
> grid)
>
> Yeah, I've tried a shared cache before and it seems to be okay.  It's a 
> bit
> messy because multiple simulators may
> attempt to clean up the cache at the same time, which results in quite a 
> few
> seeing messy "file not found" warnings,
> though these should not be harmful.
>
> It's hard to know how to get around this problem without making the cache
> yet another process or doing messy things like
> designating only one simulator to actually clean up files.  I also think 
> the
> cache needs a facility to limit by size
> (like every other cache in the known universe :).
>
> On 22/08/14 15:28, Jeff Kelley wrote:
>> At 8:09 AM -0500 22/8/14, Marcus Llewellyn wrote:
>>
>> You can indeed give each instance its own asset cache directory. My
>> rationale for not doing so is that where simulators
>> share content, this should reduce requests to the asset service, 
>> resulting
>> in less network traffic, and also a modest
>> speed up when regions are first started in some circumstances.
>>
>> Because an asset may have been cached already by another simulator.
>>
>>
>>
>> My only concern has been that a single asset cache that has multiple
>> copies of Flotsam managing it might at some point
>> encounter some sort of conflict or collision. So far, I've noticed 
>> nothing
>> of the sort, though. In practice, a single
>> asset cache has been working fine for me.
>>
>> So shared cache is a better option, until we discover a drawback.
>>
>>
>>
>> -- Jeff
>>
>>
>> _______________________________________________
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>> Opensim-users at opensimulator.org
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>>
>
>
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