[nycbug-talk] Jail Performance

George Georgalis george
Wed Jan 5 00:00:34 EST 2005

On Tue, Jan 04, 2005 at 11:10:19PM -0500, Pete Wright wrote:
>On Tue, Jan 04, 2005 at 11:01:22PM -0500, Louis Bertrand wrote:
>> On Tue, 4 Jan 2005, Pete Wright wrote:
>> > Hey nycbugers,
>> > 	I've been kicking around some ideas regarding jailing
>> > in an "enterprise" environment.  While jails do have the obvious
>> > benefit of added security; one thing that interests me are the
>> > possibilities of using jails to assist with server and app.
>> > management in distrubited envrionments.  The basic idea I am
>> > thinking of is creating jails for specific applications that
>> > get loaded to a farm of servers via PXE-TFTP.  One would netboot
>> > a server, and then dist a jail to that system after boot.  Seems
>> > simple enough...but what about performance.  Has anyone noticed
>> > any significant performance bottlenecks w/in jails.  I would not
>> > expect any, and have not seen any either.  But maybe there is
>> > something I'm missing?
>> >
>> Just a quick thought, and note that I really have no idea what I'm
>> talking aobut, but didn't you just describe IBM's VM operating
>> system for mainframes?  I think they run multiple independent
>> instances of Linux, each in its own virtual machine (hence the name).
>yes it is sorta similar to partitioning hardware on IBM or Sun gear,
>altho what I was thinking about was having a central repository of 
>system images, bundled with a specific app (say an apache tomcat
>server) that can be distributed to a group a machines.  The idea is 
>to make administration easier and allow more flexibility on how one
>can provision a group of servers.

sounds like a good idea, less the ramp up time which no doubt be
recoverable after a few image mods.

Speaking from second hand info, and I've been paying a lot of attention
to these things, I don't think you'll see a performance hit. There is
another layer of abstraction with a jail but the "cpu" doesn't really
go through it, device IO does. I expect you'll see well under 1% cpu
degrade, probably closer to 0.1%, and maybe 1% IO degrade. +/- 3% on all
that. ;-) but seriously, I think any performance hit you'll see with a
jail will be squelched by the reality of HW cost and Moore's Law, for
that last 1% you need to buy new hardware every 6 months and if you're
doing that, you'll have a nice, actual, cluster in no time. :)

// George

George Georgalis, systems architect, administrator Linux BSD IXOYE
http://galis.org/george/ cell:646-331-2027 mailto:george at galis.org

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