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[vox] [fwd] Re: Major Linux school deployments
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[vox] [fwd] Re: Major Linux school deployments

Seen on the Schoolforge mailing list:

----- Forwarded message from Dean Montgomery -----

Date: Tue, 13 Oct 2009 08:15:46 -0700 (PDT)
From: Dean Montgomery
Subject: Re: [school-discuss] Major Linux school deployments

----- "Jordan Erickson" wrote:
> WOW. What are the server specs? I *have* to assume you aren't running
> 236 clients *at the same time* from this single server.

Yes 236 clients *at the same time*, on one server : )

* Dual Quad-Core AMD Opteron (top and /proc/cpuinf show 8 CPUs)
* 4x 1G NIC ports configured as a 802.3ad bond to the core switch.
* 4 drives in raid10
* 8G RAM

When a diskless client boots NFS starts caching files in RAM so the
next diskless station that boots the files transfer directly from
server RAM to the client.  The same server caching happens for
Firefox, OpenOffice, GoogleEarth etc.  The results are that diskless
workstations have no seek time, they boot/run faster than computers
with a disk installed.

Generally Dansguardian/Squid take up more resources on the server
compared to running diskless clients.

Below are 3 system-monitor pictures of the server that runs the 236
clients.  You will notice a network peak around 7AM when all the
clients etherwake in the morning.  We install preload on the clients
to prefetch KDE OpenOffice Firefox etc into RAM.


Another benefit to having all the data stored centrally in the school
is a very cool off-site backup system that Freddie and Brent built for
our district.  It takes about 8 hours to do a FULL backup of our 117
linux/bsd servers every night.  The backup stores 200+ days of
incremental backups.  Teachers can now ask "please restore file XYZ
from September 9 2009".  When a school server was stolen it took us
1/2 day to restore the backups and have them running again.  A full
server restore from backup takes 1-2 hours.

Using the rsync backup in our biggest school:
* ~1520 students
* ++ staff
* 236 diskless clients
* transfers about 1.5G per day for it's backup.
* takes 8 hours at night ( this is in parallel with 117 other schools,
  allot less time if it were on it's own )

rsync scans each file and only sends the difference of the files.
rsync does not send files that already have been backed up.

Note because we do a parallel backup of 117 servers at night it takes
a bit longer.  If you were doing off-site rsync backup of only one or
two servers, rsync is very fast.  For example our simple firewall
boxes only take about 2 minutes to do a full off-site backup.

So all student data & all staff data plus all Linux/BSD OS +
OS-customizations get full backups every night.  Windows computers
only get My Documents backed up *IF* the MyDoc folder is mapped to the
server's samba share.  We all know how many hours are wasted when a
Windows C drive dies.  When any server drive dies on the RAID, a site
tech powers off the server, replaces the drive and powers it up in
with about 10 minutes down time.

Another benefit is uptime.  I've seen over 400 days uptime on the
school servers.  We now shut them down during the summer so it is hard
to tell how long they will actually run for.

Dean Montgomery
Network Support Tech./Programmer
dmonty [[ sd73 ]] bc ]] ca
School District #73

----- End forwarded message -----
[[=@ ]]=.

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