[K12OSN] New Building's LTSP Server
news at siddall.name
Mon Apr 18 17:22:58 UTC 2011
On 04/18/2011 12:29 PM, Joseph Bishay wrote:
> On Mon, Apr 18, 2011 at 9:30 AM, Jeff Siddall <news at siddall.name> wrote:
>> Personal opinions:
>> You are definitely going to need more than 2 GB RAM. CPU seems less
>> important. I am running a quad core Phenom II, 8 GB with about 20
>> clients total, 10 or so being steadily used.
> Is there a link to your specific type of machine so I can learn more
> about pricing / specs?
Nope, I build all my machines from scratch. If you are looking at using
desktop PC parts (ie: <$2,000 systems) it is the best way to optimize
performance. You get exactly what you want, nothing you don't.
Have a look at some parts like these as a starting point:
6 core 3.2 GHz CPU: about $200:
16 GB DDR3: about $225:
50 GB RevoDrive: about $205 each:
Add a motherboard of your choosing and case/PS for another $200 and you
have a pretty quick server for less than $1000. If you need bulk
storage throw in a 2TB drive but if possible keep root and home dirs on
>> No performance issues
>> except it is easy for the GigE to get saturated if there are clients
>> playing video. Video is killer for LTSP. If you don't install flash
>> your life will be better :)
> Unfortunately as this is an elementary school, as much as I'd love to
> not have flash, I know it will be 100% required :)
Yeah, maybe look at adding an extra NIC and splitting your clients or
doing a MLT. Someone else posted detailed instructions on splitting the
>> I would avoid SCSI drives. Not because they are bad, but because your
>> money could probably be better spent elsewhere. Modern SATA drives
>> perform great. Also, definitely go with RAID1. Not only will it buy
>> you survivability but you get 2X the read performance. Software raid
>> works fine. Avoid RAID5. If you can afford it try SSDs. They will
>> vastly increase the random IO ability of your system which is especially
>> important for LTSP.
> Would you say that the much higher cost of SSD and their read/write
> lifespan limits are still better than SCSI?
The lifespan will probably be less for a SSD but they have been making
those for a lot of years now so I don't think you will have problems in
the short term.
As for performance, the RevoDrive I referenced above will blow the doors
off _any_ platter drive at _any_ price -- SCSI or otherwise.
Even if you want to stick with platter drives SATA still performs well.
I did an rsync to my RAID1 array of relatively slow WD RE2 GP drives
and was getting sustained _write_ speeds of well over 200 MB/s. Not too
Either way, the killer for platters is random IO and a SCSI drive can't
get the heads to a chunk of data any quicker than a SATA drive with the
same speed/platter configuration.
> I've been running RAID1 so I'd continue to do that for sure.
>> You might be better off building two
>> smaller servers for the same price. You might also run into scaling
>> issues with file handles and whatnot with a large number of logged-in
>> clients. Google for people who ran into that and the resolution they
> I have been thinking about this but this would be entirely new for me
> so I'm a bit hesitant. I also need to be able to sync the /home
> directories of a small sub-set of users when they log out with another
> remote server so I'm not sure if one location has a all-in-one LTSP
> server and the other has a different multi-server configuration if it
> will easily work or not.
If you have to sacrifice things like SSD and RAM to get to two servers
there probably isn't much benefit -- especially if you keep bandwidth
intensive stuff like flash on the clients.
>> Localapps for pig apps like Firefox may help save your server performance.
> This may be the cleanest solution as 90% of the time people will be
> running Firefox.
Definitely do that if you can. Everyone will be happier.
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