Hello--
As part of my research in file systems, I have written an NFS
tracing program (based largely on tcpdump, but with the ability to
capture more information) and a bunch of PERL scripts for scanning
through the traces and finding useful info. It has been very useful
to my work, and from my conversations with other people, I think it
might be a useful tool to other people. I'd like to document and
bundle up the tools I have and/or add some new tools that make them
useful in a general context. However, I don't really know what
functionality other people are looking for.
Here's where you can help. I'm trying to put together a wish list of
NFS analysis tools -- what tools would you like that you haven't got?
Some ideas people have already suggested:
- Load pattern analysis.
If your network is like ours, then 3am is not a good time to
do backups. Everyone thinks the system is idle in the middle
of the night, so they all schedule their big jobs to run in
the small hours of the morning...
- Hot file/directory spotting.
Watch for files that get read a lot by lots of clients, but
not written. (maybe they can be replicated, possibly closer
to the clients)
- Hot client spotting.
For servers with multiple interfaces on different subnets,
figure out which clients are soaking up all the bandwidth and
spread them out between the subnets to balance the load.
These are pretty mundane. Tell me what you really want...
Thanks,
-Dan
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On Thu, 10 Apr 2003, Daniel Ellard wrote:
> Here's where you can help. I'm trying to put together a wish list of
> NFS analysis tools -- what tools would you like that you haven't got?
Some network related information to pinpoint problems with the network.
For example, look at retransmits (there is only a system wide counter
available right now): if a server has lots of retransmits pretty equal
distributed among clients, this might indicate a problem with network
connection of the server or the network in general; if the retransmits
happen mostly to a reduced number of clients, the clients are most likely
at fault.
When retransmitting, lowering rsize/wsize might reduce retransmissions,
while lowering the maximum transfer bandwidth. So, if some client has
problems with retransmissions, check if another client which is behaving
well has a lower rsize/wsize - if so, suggest lowering it to the same
value also on the troubled client... (this probably means keeping track of
a lot of data, so I don't know how feasible it is).
Another thing which might be useful is a measure of time for replies, to
diagnose the "Can't get request slot" messages. If the server replies
quickly it means the return path to the client is broken (that might mean
even the network connection of the server, as the reply is seen before it
gets in the transmit queue of the network driver). But if the server
replies too slow, then the server is overloaded.
--
Bogdan Costescu
IWR - Interdisziplinaeres Zentrum fuer Wissenschaftliches Rechnen
Universitaet Heidelberg, INF 368, D-69120 Heidelberg, GERMANY
Telephone: +49 6221 54 8869, Telefax: +49 6221 54 8868
E-mail: [email protected]
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response times should probably also be built into nfsstat -m (as on other
clients).
-----Original Message-----
From: Bogdan Costescu [mailto:[email protected]]
Sent: 14 April 2003 13:48
To: Daniel Ellard
Cc: [email protected]
Subject: Re: [NFS] NFS trace wish list?
On Thu, 10 Apr 2003, Daniel Ellard wrote:
> Here's where you can help. I'm trying to put together a wish list of
> NFS analysis tools -- what tools would you like that you haven't got?
Some network related information to pinpoint problems with the network.
For example, look at retransmits (there is only a system wide counter
available right now): if a server has lots of retransmits pretty equal
distributed among clients, this might indicate a problem with network
connection of the server or the network in general; if the retransmits
happen mostly to a reduced number of clients, the clients are most likely
at fault.
When retransmitting, lowering rsize/wsize might reduce retransmissions,
while lowering the maximum transfer bandwidth. So, if some client has
problems with retransmissions, check if another client which is behaving
well has a lower rsize/wsize - if so, suggest lowering it to the same
value also on the troubled client... (this probably means keeping track of
a lot of data, so I don't know how feasible it is).
Another thing which might be useful is a measure of time for replies, to
diagnose the "Can't get request slot" messages. If the server replies
quickly it means the return path to the client is broken (that might mean
even the network connection of the server, as the reply is seen before it
gets in the transmit queue of the network driver). But if the server
replies too slow, then the server is overloaded.
--
Bogdan Costescu
IWR - Interdisziplinaeres Zentrum fuer Wissenschaftliches Rechnen
Universitaet Heidelberg, INF 368, D-69120 Heidelberg, GERMANY
Telephone: +49 6221 54 8869, Telefax: +49 6221 54 8868
E-mail: [email protected]
-------------------------------------------------------
This sf.net email is sponsored by:ThinkGeek
Welcome to geek heaven.
http://thinkgeek.com/sf
_______________________________________________
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https://lists.sourceforge.net/lists/listinfo/nfs
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Welcome to geek heaven.
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