Re: [school-discuss] Major Linux school deployments

[Dean Montgomery <dmonty@xxxxxxxxxx>]

----- "Jordan Erickson" <jerickson@xxxxxxxxxxxxxxxxxxxxx> 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.
http://www.sd73.bc.ca/district-operations/tmp-images/

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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.

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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@xxxxxxxxxx
School District #73