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Obsolete:Lopar cluster

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This page contains historical information. It may be outdated or unreliable.

The Lopar cluster was hosted in rack space provided by Lost Oasis near Paris.


"lo" comes from Lost Oasis. "PAR" is the generic code airports near Paris.


See caching servers out of Florida for rationale and performance.
  • Hardware
    • 3 x 600MHz Celeron 1U machines with 20GB HDD – HP Web Hosting Server Appliance sa1100 - specs: [1]
    • 2 serial ports, 2 NICs, no graphics card
    • Debian
    • use PC133 ECC unregistered DIMMs, 256 MiB max per DIMM, 4 slots per machine (possibility of using registered RAM? probably only if all DIMMs are registered)
    • ennael: 768 MiB RAM (original 128 MiB DIMM faulty and removed on January 12, 2005; 256 MiB DIMM installed on Sunday 16, 2005); chloe, bleuenn: 640 MiB RAM (128 in original machine + 2 × 256 upgrade)
    • On the way, waiting to be installed: sophie and florence (same specs, 128 MiB RAM, waiting for 768 MiB extension each).
  • Network connectivity
    • Dexlan 5-port 100base-TX Ethernet switch (port 1=uplink, ports 2-4=squids, port 5=free); all cables straight;
    • names are chloe (, bleuenn (, and ennael (;
    • addresses and may also be used to connect other machines (laptop for maintenance...);
    • IP block :
      • they now grant us /28 but we haven't yet redone the setup
    • Network :
    • Netmask :
    • Broadcast :
    • Gateway :
    • DNS:
  • null-modem serial cables run from ttyS1 on one machine to ttyS0 on another; setting is 19200 bps;
    • getty running on ttyS0 on each machine, to allow communication using minicom;
    • order (caller to listener) is chloe → ennael → bleuenn → chloe;
    • BIOS, grub and kernel all configured for serial console; BIOS and grub accessible through serial console;
    • as a consequence, any remote rebooting should be made by logging into the preceding machine in the ring and running minicom onto the machine to be rebooted;
  • rack space provided by Lost Oasis inside the Telecity colocation in Aubervilliers near the northern city limits of Paris.
  • Contact: Med or Submarine.

Network specificities

Obsolete information

The network provider that gives us rack space and bandwidth for free pays a lot for transit to certain destinations. Because of this, they throttle those destinations with a maximum traffic going out of our host, at the level of the last router.

The symptoms for this are long ping times from the affected networks.

It especially looks like anything going through OpenTransit.net is throttled to approximatively 5 Mbits/s.

Normally, this throttling does not concern any network in France. However, on Sunday, January 16 evening, networking problems caused ALL traffic, including French traffic, to go through OpenTransit and thus to be throttled.

As of January 20, all traffic restrictions were lifted. The provider will warn us if we use too much transit.

Obsolete status

See Ielo's page for network status. ->traffic graph

From broadband connections in France, at off-peak times, the download speed for large files is around 80 kiB/s when not in cache and 235 kiB/s when in cache.

Countries and content concerned

fr:, en:, commons and upload (all wikis) were cached for Belgium, France, Luxembourg, Switzerland and the United Kingdom. Germany removed due to insufficient servers.