I started with nfs-iostat.py, Realized that nfsiostat that ships with CentOS seems to be the same python script. Output is identical and if you diff the two scripts they're almost identical.
Under the impression that RTT (round trip time) is the same as latency.
But in either case the RTT figures given are averaged since the last reboot if you run it with no arguments, and if you run it with arguments of "1 1" it's not clear what you're actually getting.
I'm looking for something I can run once a minute that will tell me the latency of the NFS mounts in real time.
----- Original Message ----- From: "Andrey Borzenkov" andrey.borzenkov@ts.fujitsu.com To: "Randy Rue" rrue@fhcrc.org Cc: toasters@teaparty.net Sent: Wednesday, February 1, 2012 10:08:14 PM Subject: RE: nfsiostat and client NFS connections
Hmm ... but nfsiostat does not really display latency, unless you have some customized version. You want nfs-iostat.py for it: http://communities.netapp.com/thread/13445
--- With best regards
Andrey Borzenkov Senior system engineer Service operations
-----Original Message----- From: Randy Rue [mailto:rrue@fhcrc.org] Sent: Thursday, February 02, 2012 8:31 AM To: Borzenkov, Andrey Cc: toasters@teaparty.net Subject: Re: nfsiostat and client NFS connections
I appreciate your feedback.
I'm attempting to get some real-time view of current latency for NFS mounts, but have figured out that running nfsiostat returns the average since boot. Running it with multiple iterations in one call seems to return transient data, but running a single 1 second iteration doesn't.
Our ultimate goal is to capture instantaneous latency figures from several clients, post the average of those latencies and the single worst figure into an RRD database, and give a graph showing average and worst case. Can you suggest a way to do this with nfsiostat, or a better way with some other tool?
----- Original Message ----- From: "Andrey Borzenkov" andrey.borzenkov@ts.fujitsu.com To: "Randy Rue" rrue@fhcrc.org, toasters@teaparty.net Sent: Wednesday, February 1, 2012 7:33:02 PM Subject: RE: nfsiostat and client NFS connections
You do not say how you process results nor how you run nfsiostat.
nfsiostat (just like iostat, vmstat, ...) reports delta for measurement interval. The very first line is always totals since kernel boot. Usually nfsiostat is run with interval argument ("nfsiostat 60" will give you stats every minute). If you invoke it every minute you have to compute delta yourself.
There are other ways to collect information in form easier to postprocess than nfsiostat free form text output. Sadc + sadf to produce CSV, XML or other formats (which are part of the same sysstat package), collectl (can maintain RRD database) etc.
________________________________________ From: toasters-bounces@teaparty.net [toasters-bounces@teaparty.net] On Behalf Of Randy Rue [rrue@fhcrc.org] Sent: Thursday, February 02, 2012 02:33 To: toasters@teaparty.net Subject: nfsiostat and client NFS connections
Hello All,
Trying to troubleshoot performance problems on our v3170. This is not specifically a NetApp question but if nothing else, the tool I'm using appears to have been written by a NetApp engineer, does that count?
Running nfsiostat on a handful of impacted clients on another network and uploading the results to a timestamped log file served on a web server so I can reach them. I have a script that parses those pages, takes the last timestamped entry from each file (one file for each client), and tallies up a) the average RTT time for all mounts to the vFiler and b) the worst single instance.
Now that I have it all working, the numbers don't believe like I think they should. The clients are adding an entry to each file every minute. I can see that from the timestamps before each entry. But the numbers don't change. Or they change by a few hundredths of a ms. My gather script returns an average that varies only by .01ms or so, and my "worst" figure has been steady for an hour now.
We're running nfsiostat with no arguments. Am I getting real time readings or some average? If average, since when? Is there a way to get real-time?
Hope to hear from you,
Randy Rue
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