[Beowulf] Building new cluster - estimate

Paulo Afonso Lopes pal at di.fct.unl.pt
Thu Aug 7 09:09:15 EDT 2008

> Chris Samuel wrote:
>> ----- "Robert G. Brown" <rgb at phy.duke.edu> wrote:
>>> And even on Linux machines, NFS has been, well, "functional"
>>> is a good way to describe it.
>> It actually seems to work pretty well these days, our
>> general config is:
>> 1) No automounter
>> 2) Hard mounts (so jobs just hang if they loose contact)
>> 3) NFS over TCP (NFS over UDP is sooo 1990's :-))
>> 4) Jumbo frames (9000 byte MTUs) on the NFS network
>> 5) NFS file server has hardwired fsid's to prevent stale file handles
>> a reboot
>> 6) Debian, not RHEL on the server
>> 7) XFS for /home on the server
> Speaking of jumbo frames, I'm seeing a problem on a Broadcom 57xx
chipset on CentOS 4.3, 2.6.9-67 kernel (yeah, I know) and a tg3 driver.
>   I can't make the thing recognize the ability to use jumbo frames.
> Anyone got a fix?

Are you sure the chip does support jumbo? E.g., BCM5721 integrated in HP
DL145-G2 does not, while BCM5703X integrated in IBM x335 does support it.

While we're on that subject, I'm going to wire the HPs to a different
switch; I have the ideia that when started using them both connected to
the same SMC8624T switch, funny things happened with the eth1 jumbo
interfaces on the IBMs... (I'm keeping eth0 on 1500)

Anyone has had this behaviour? Is mixing (jumbo and 1500-sized) on the
same "segment" standard, or is it a chip/switch/whatever issue?



Paulo Afonso Lopes                        | Tel: +351- 21 294 8536
Departamento de Informática               | 294 8300 ext.10763
Faculdade de Ciências e Tecnologia        | Fax: +351- 21 294 8541
Universidade Nova de Lisboa               | e-mail: pal at di.fct.unl.pt
2829-516 Caparica, PORTUGAL

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