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20030902: LDM feeds from the University of Michigan (fwd)



>From:  Perry Samson <address@hidden>
>Organization:  University of Michigan
>Keywords:  200309021820.h82IKnLd025587 LDM IDD Linux

Hi Perry,

Steve Emmerson asked me to respond to your inquiry about our view of
you upgrading your IDD relay node to a Linux box (exchange included
below).

The fraction of Unidata sites using Linux as their IDD node
has grown over the years to be almost comparable to the numbers
using Sun SPARC.  The only drawback we can identify with using
Linux is the limit on the LDM queue size that it imposes (3 GB).
Since the great majority of IDD relay and leaf node sites are
running LDMs with queues smaller than 2 GB, this limitation
should not be considered a "show stopper".  The primary top level
IDD relay nodes operated by the UPC, on the other hand, are
all Sun SPARC machines, and we are using LDM queues in excess
of 2 GB (6 GB on thelma.ucar.edu, and 4 GB on atm.geo.nsf.gov).
So, our "official" position on moving to Linux is fairly neutral,
but no alarms were set off by the inquiry.

As a last comment, we have been experimenting with FreeBSD for
the PC IDD nodes that we operate, and we like it a lot.  My
observation over the past couple of years is that FreeBSD is
measurably faster than Linux running on the exact same hardware,
and it is more secure than Linux.  The drawback with FreeBSD
is that there are not nearly as many sites using it as are
using Linux, so getting help from peers is not nearly as easy.

Cheers,

Tom

>Date: Tue, 2 Sep 2003 13:34:15 -0400
>From: Perry Samson <address@hidden>
>Subject: Re: LDM feeds from the University of Michigan
>
>       Steve,
>
>       Such an offer would be sweet.  I'm confident our
>       students will be rise to the occasion (and drag their
>       faculty along in the process) but having some overseeing
>       hands for at least a while would be invaluable.
>
>       Having caused this chaos our department is also exploring
>       the pros and cons of moving to a bigger machine running
>       Linux (from the current Sun).  Would this be viewed as a
>       plus or minus by the UPC?
>
>       Perry
>
>
>
>>Hi Perry,
>>
>>>Date: Sat, 30 Aug 2003 10:35:15 -0400
>>>From: Perry Samson <address@hidden>
>>>To: address@hidden
>>>Subject: LDM feeds from the University of Michigan
>>
>>The above message contained the following:
>>
>>>     I'd like to clarify a previous message about the University
>>>     of Michigan's participation in the LDM system.  The significant
>>>     change is we moving from having a dedicated staff person oversee
>>>     LDM to having the LDM maintenance performed by our students.
>>>
>>>     That said, we also want to be honest that our students are new
>>>     to the process.  Over the short term we therefore recommend you
>>>     consider alternative feeds while our students learn the ropes.
>>
>>I've been corresponding with Thomas about the possibility of the UPC
>>remotely helping to keep your LDM system running.  As a well-connected,
>>relay node, it would seem in everyone's interest to keep you up.
>>
>>No promises, of course -- and please don't spread this around just yet.
>>
>>What do you think?
>>
>>Regards,
>>Steve Emmerson
>>LDM Developer
>
>
>- -- 
>  _____________________________________________________________________
>|   Prof. Perry J. Samson                                            |
>|   Associate Chair for Academic Affairs                             |
>|   Department of Atmospheric, Oceanic and Space Sciences            |   
>|--------------------------------------------------------------------|
>|   1539 Space Research Building       734-763-6213  [office]        |
>|   University of Michigan             734-763-5376  [fax]           |
>|   Ann Arbor, Michigan  48109-2143                                  |
>|____________________________________________________________________|
>
>------- End of Forwarded Message
>
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