Perl OnTAP SDK: Realtime NFS Latency - The Practical Administrator

Since most of my Virtual Infrastructure runs on NFS datastores I like to keep a very close eye on what’s going on inside the NetApp. I generally use Cacti for long term monitoring of the status of the datastores and the NetApp as a whole.

However, when I want to see what’s going on in less than five minute increments, Cacti is pretty much useless. I wrote this script a while ago so that if I feel that latency is becoming a problem, I can check it right away and see it in frequent intervals.

Most often I use this script when Nagios starts to chirp at me. I use a slightly modified version of this script with Nagios and have it alert when latency gets out of hand. I then use this script to get a good look at what’s going on.

The OnTAP SDK is almost as entertaining to work with as VMware’s…

#!/usr/bin/perl -w
#
# na-realtime-nfs-latency.pl - written by Andrew Sullivan, 2009-06-23
#
# Please report bugs and request improvements at http://practical-admin.com/blog/?p=758
#
# I wanted a way to see the realtime nfs latency as reported by a NetApp 
# appliance.  This perl script uses the OnTAP SDK to query the NetApp for
# the performance stats and display back the latency and operations performed.
#
# The latency is found by measuring the total latency and total ops at two 
# intervals.  The first set of values is subtracted from the second, and then
# the ops are divided into the total latency giving us average latency.
#
# Examples:
#   This will query the appliance every 15 seconds to display the latency.  I don't
#   provide a password because it will ask for one if it's not provided.
#     na-realtime-nfs-latency.pl --hostname toaster --username not_root --interval 10
#
#   Same as above, but with the abbreviated options
#     na-realtime-nfs-latency.pl -H toaster -u not_root -i 10
#
# TODO:
#   Modify to work for all versions of NFS, not just 3
#

# I placed the NetApp perl modules into my perl lib directory, however,
# if you haven't done this, you will probably need to specify where they
# are using a lib declaration
#use lib "NetApp";
use NaServer;
use NaElement;

use Getopt::Long qw(:config no_ignore_case);

main( );

sub main {
	my $opts = parse_options();
	my $server = get_filer( $opts-&gt;{ 'hostname' }, $opts-&gt;{ 'username' }, $opts-&gt;{ 'password' } );

	# print a nice header 
	printf '%14s %10s %14s %10s', "Read Latency", "Read Ops", "Write Latency", "Write Ops";
	print "n" . "-" x 14 . " " . "-" x 10 . " " . "-" x 14 . " " . "-" x 10 . "n";
	
	# initialize the first data set
	my $first = get_latency( $server );
	
	while (1) {
		# zeroize the counters
		my $nfs_read_latency = 0;
		my $nfs_write_latency = 0;
		my $nfs_read_ops = 0;
		my $nfs_write_ops = 0;

		# wait the specified amount 
		sleep $opts-&gt;{ 'interval' };

		# gather the second set of values
		my $second = get_latency( $server );
		
		# check to make sure we don't divide by zero
		if ($second-&gt;{'avg_read_latency_base'} &gt; $first-&gt;{'avg_read_latency_base'}) {
			$nfs_read_ops = $second-&gt;{'avg_read_latency_base'} - $first-&gt;{'avg_read_latency_base'};
			$nfs_read_latency = ($second-&gt;{'read_latency'} - $first-&gt;{'read_latency'}) / $nfs_read_ops;
		}
		
		if ($second-&gt;{'avg_write_latency_base'} &gt; $first-&gt;{'avg_write_latency_base'}) {
			$nfs_write_ops = $second-&gt;{'avg_write_latency_base'} - $first-&gt;{'avg_write_latency_base'};
			$nfs_write_latency = ($second-&gt;{'write_latency'} - $first-&gt;{'write_latency'}) / $nfs_write_ops;
		}

		# print the data
		printf '%11.2f ms %10i %11.2f ms %10i', $nfs_read_latency / 1000, $nfs_read_ops, $nfs_write_latency / 1000, $nfs_write_ops;
		print "n";
		
		# shift our values
		$first = $second;

	}
}

### Supporting subroutines ###

#
# Prints the usage information
#
sub print_usage {
	print &lt;&lt;EOL
  Missing or incorrect arguments!

  na-realtime-nfs-latency.pl --hostname|-H  
            --username|-u  
          [ --password|-p  ]
          [ --interval|-i  ]

  na-realtime-nfs-latency.pl --help|-h

  It is not necessary to supply a password during the command line
  call.  If it is not provided, it will be asked for.

EOL

}

#
# Defines and parses the options from the command line, also
# checks to make sure that options are valid.  Will prompt for
# a password if one is not provided.
#
sub parse_options {
	
	my %options = (
		'hostname' =&gt; '',
		'username' =&gt; '',
		'password' =&gt; '',
		'interval' =&gt; 30,
		'help'     =&gt; 0
	);
	
	GetOptions( %options,
		'hostname|H=s',
		'username|u=s',
		'password|p:s',
		'interval|i:i',
		'help|h'
	);
	
	if (! $options{ 'hostname' } || ! $options{ 'username' } || $options{ 'help' }) {
		print_usage();
		exit(1);
	}

	if (! $options{ 'password' }) {
		print "Enter password: ";
		if ( $^O eq "MSWin32" ) {
			require Term::ReadKey;

			Term::ReadKey-&gt;import( qw(ReadMode) );
			Term::ReadKey-&gt;import( qw(ReadLine) );
			ReadMode('noecho');

			chomp( $options{ 'password' } = ReadLine(0) );

			ReadMode('normal');

		} else {
			system("stty -echo") and die "ERROR: stty failedn";
			
			chomp ( $options{ 'password' } =  );
			
			system("stty echo") and die "ERROR: stty failedn";
			
		}

		print "n";
	}
	
	return %options;
}

#
# Creates the NaServer object
#
sub get_filer {
	my ($hostname, $username, $password) = @_;
	
	my $s = NaServer-&gt;new($hostname, 1, 7);
	$s-&gt;set_style(LOGIN_PASSWORD);
	$s-&gt;set_admin_user($username, $password);
	$s-&gt;set_transport_type(NA_SERVER_TRANSPORT_HTTP);
	
	return $s;
}

# 
# Queries the NetApp and returns a hash of responses
#
sub get_latency {
	my $server = shift;
	my $return = {};
	
	my $request = build_request();
	my $result = $server-&gt;invoke_elem( $request );
	
	foreach ($result-&gt;child_get('instances')-&gt;child_get('instance-data')-&gt;child_get('counters')-&gt;children_get()) {
		my $name = $_-&gt;child_get_string('name');
		$name =~ s/nfsv[2|3|4]_//;
		
		$return-&gt;{ $name } = $_-&gt;child_get_string('value');
	}
	
	return $return;
}

# 
# creates the NaElement tree for querying latency
#
sub build_request {
	my $request = NaElement-&gt;new('perf-object-get-instances');
	$request-&gt;child_add_string('objectname', 'nfsv3');
	
	my $counters = NaElement-&gt;new('counters');
	
	$counters-&gt;child_add_string('counter', 'nfsv3_read_latency');
	$counters-&gt;child_add_string('counter', 'nfsv3_write_latency');
	$counters-&gt;child_add_string('counter', 'nfsv3_avg_read_latency_base');
	$counters-&gt;child_add_string('counter', 'nfsv3_avg_write_latency_base');

	$request-&gt;child_add( $counters );
	
	return $request;
}

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#!/usr/bin/perl -w

# na-realtime-nfs-latency.pl - written by Andrew Sullivan, 2009-06-23

# Please report bugs and request improvements at http://practical-admin.com/blog/?p=758

# I wanted a way to see the realtime nfs latency as reported by a NetApp

# appliance. This perl script uses the OnTAP SDK to query the NetApp for

# the performance stats and display back the latency and operations performed.

# The latency is found by measuring the total latency and total ops at two

# intervals. The first set of values is subtracted from the second, and then

# the ops are divided into the total latency giving us average latency.

# Examples:

# This will query the appliance every 15 seconds to display the latency. I don't

# provide a password because it will ask for one if it's not provided.

# na-realtime-nfs-latency.pl --hostname toaster --username not_root --interval 10

# Same as above, but with the abbreviated options

# na-realtime-nfs-latency.pl -H toaster -u not_root -i 10

# TODO:

# Modify to work for all versions of NFS, not just 3

# I placed the NetApp perl modules into my perl lib directory, however,

# if you haven't done this, you will probably need to specify where they

# are using a lib declaration

#use lib "NetApp";

use NaServer;

use NaElement;

use Getopt::Long qw(:config no_ignore_case);

main( );

sub main {

my $opts = parse_options();

my $server = get_filer( $opts->{ 'hostname' }, $opts->{ 'username' }, $opts->{ 'password' } );

# print a nice header

printf '%14s %10s %14s %10s', "Read Latency", "Read Ops", "Write Latency", "Write Ops";

print "n" . "-" x 14 . " " . "-" x 10 . " " . "-" x 14 . " " . "-" x 10 . "n";

# initialize the first data set

my $first = get_latency( $server );

while (1) {

# zeroize the counters

my $nfs_read_latency = 0;

my $nfs_write_latency = 0;

my $nfs_read_ops = 0;

my $nfs_write_ops = 0;

# wait the specified amount

sleep $opts->{ 'interval' };

# gather the second set of values

my $second = get_latency( $server );

# check to make sure we don't divide by zero

if ($second->{'avg_read_latency_base'} > $first->{'avg_read_latency_base'}) {

$nfs_read_ops = $second->{'avg_read_latency_base'} - $first->{'avg_read_latency_base'};

$nfs_read_latency = ($second->{'read_latency'} - $first->{'read_latency'}) / $nfs_read_ops;

}

if ($second->{'avg_write_latency_base'} > $first->{'avg_write_latency_base'}) {

$nfs_write_ops = $second->{'avg_write_latency_base'} - $first->{'avg_write_latency_base'};

$nfs_write_latency = ($second->{'write_latency'} - $first->{'write_latency'}) / $nfs_write_ops;

}

# print the data

printf '%11.2f ms %10i %11.2f ms %10i', $nfs_read_latency / 1000, $nfs_read_ops, $nfs_write_latency / 1000, $nfs_write_ops;

print "n";

# shift our values

$first = $second;

}

### Supporting subroutines ###

# Prints the usage information

sub print_usage {

print <<EOL

Missing or incorrect arguments!

na-realtime-nfs-latency.pl --hostname|-H

--username|-u

[ --password|-p ]

[ --interval|-i ]

na-realtime-nfs-latency.pl --help|-h

It is not necessary to supply a password during the command line

call. If it is not provided, it will be asked for.

EOL

}

# Defines and parses the options from the command line, also

# checks to make sure that options are valid. Will prompt for

# a password if one is not provided.

sub parse_options {

my %options = (

'hostname' => '',

'username' => '',

'password' => '',

'interval' => 30,

'help' => 0

);

GetOptions( %options,

'hostname|H=s',

'username|u=s',

'password|p:s',

'interval|i:i',

'help|h'

);

if (! $options{ 'hostname' } || ! $options{ 'username' } || $options{ 'help' }) {

print_usage();

exit(1);

}

if (! $options{ 'password' }) {

print "Enter password: ";

if ( $^O eq "MSWin32" ) {

require Term::ReadKey;

Term::ReadKey->import( qw(ReadMode) );

Term::ReadKey->import( qw(ReadLine) );

ReadMode('noecho');

chomp( $options{ 'password' } = ReadLine(0) );

ReadMode('normal');

} else {

system("stty -echo") and die "ERROR: stty failedn";

chomp ( $options{ 'password' } = );

system("stty echo") and die "ERROR: stty failedn";

}

print "n";

}

return %options;

}

# Creates the NaServer object

sub get_filer {

my ($hostname, $username, $password) = @_;

my $s = NaServer->new($hostname, 1, 7);

$s->set_style(LOGIN_PASSWORD);

$s->set_admin_user($username, $password);

$s->set_transport_type(NA_SERVER_TRANSPORT_HTTP);

return $s;

}

# Queries the NetApp and returns a hash of responses

sub get_latency {

my $server = shift;

my $return = {};

my $request = build_request();

my $result = $server->invoke_elem( $request );

foreach ($result->child_get('instances')->child_get('instance-data')->child_get('counters')->children_get()) {

my $name = $_->child_get_string('name');

$name =~ s/nfsv[2|3|4]_//;

$return->{ $name } = $_->child_get_string('value');

}

return $return;

}

# creates the NaElement tree for querying latency

sub build_request {

my $request = NaElement->new('perf-object-get-instances');

$request->child_add_string('objectname', 'nfsv3');

my $counters = NaElement->new('counters');

$counters->child_add_string('counter', 'nfsv3_read_latency');

$counters->child_add_string('counter', 'nfsv3_write_latency');

$counters->child_add_string('counter', 'nfsv3_avg_read_latency_base');

$counters->child_add_string('counter', 'nfsv3_avg_write_latency_base');

$request->child_add( $counters );

return $request;

}

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