This article is going to show the basic configuration of snmptrapd and it’s traphandle command.

Assumptions:
snmptrapd is running on a linux host named “test-centos”;
The host sending snmptrap messages in this example is named “test-zfs-host”

Now first we’re going to set snmptrapd up on the snmptrap server side:

###Server side
[root@test-centos snmp]# cat /etc/snmp/snmptrapd.conf
#traphandle default /bin/mail -s “snmpdtrapd messages” <put your mail address here>
traphandle default /root/lognotify
authCommunity log,execute,net public

[root@test-centos snmp]# service snmptrapd restart

[root@test-centos snmp]# cat /root/lognotify
#!/bin/bash
read host
read ip
vars=

while read oid val
do
if [ "$vars" = "" ]
then
vars=”$oid = $val”
else
vars=”$vars, $oid = $val”
fi
done
echo trap: $host $ip $vars >/var/tmp/snmptrap.out

And to test whether snmptrapd is working as expected:

###On client side
snmptrap -v2c -c public test-centos:162 “” SNMPv2-MIB::sysDescr SNMPv2-MIB::sysDescr.0 s “test-zfs-host test-zfs-host.ip this is a test snmptrap string”

And after running this command, you can have a check of /var/tmp/snmptrap.out on the snmptrapd server side(test-centos):

[root@test-centos ~]# cat /var/tmp/snmptrap.out

PS:
If you’re using sun zfs head, you can set snmptrap destinations in zfs BUI(configuration -> SNMP), here’s the snapshot(click to see the larger image):

On zfs’s aksh, I can check memory usage with the following:

test-zfs:> status memory show
Memory:
Cache 719M bytes
Unused 15.0G bytes
Mgmt 210M bytes
Other 332M bytes
Kernel 7.79G bytes

So now I want to collect this memory usae information automatically for SNMP’s use. Here’s the steps:

cpan> o conf prerequisites_policy follow
cpan> o conf commit

Since the host is using proxy to get on the internet, so in /etc/wgetrc:

http_proxy = http://www-proxy.us.example.com:80/
ftp_proxy = http://www-proxy.us.example.com:80/
use_proxy = on

Now install the Net::SSH::Perl perl module:

PERL_MM_USE_DEFAULT=1 perl -MCPAN -e ‘install Net::SSH::Perl’

And to confirm that Net::SSH::Perl was installed, run the following command:

perl -e ‘use Net::SSH::Perl’ #no output is good, as it means the package was installed successfully

Now here goes the perl script to get the memory usage of sun zfs head:

[root@test-centos ~]# cat /var/tmp/mrtg/zfs-test-zfs-memory.pl
#!/usr/bin/perl
use strict;
use warnings;
use Net::SSH::Perl;
my $host = ‘test-zfs’;
my $user = ‘root’;
my $password = ‘password’;

my $ssh = Net::SSH::Perl->new($host);
$ssh->login($user,$password);
my ($stdout,$stderr,$exit) = $ssh->cmd(“status memory show”);
$ssh->cmd(“exit”);
if($stderr){
print “ErrorCode:$exit\n”;
print “ErrorMsg:$stderr”;
} else {
my @std_arr = split(/\n/, $stdout);
shift @std_arr;
foreach(@std_arr) {
if ($_ =~ /.+\b\s+(.+)M\sbytes/){
$_=$1/1024;
}
elsif($_ =~ /.+\b\s+(.+)G\sbytes/){
$_=$1;
}
else{}
}
foreach(@std_arr) {
print $_.”\n”;
}
}
exit $exit;

PS:
If you get the following error messages during installation of a perl module:

[root@test-centos ~]# perl -MCPAN -e ‘install SOAP::Lite’
CPAN: Storable loaded ok
CPAN: LWP::UserAgent loaded ok
Fetching with LWP:
ftp://ftp.perl.org/pub/CPAN/authors/01mailrc.txt.gz
LWP failed with code[500] message[LWP::Protocol::MyFTP: connect: Connection timed out]
Fetching with Net::FTP:
ftp://ftp.perl.org/pub/CPAN/authors/01mailrc.txt.gz

Trying with “/usr/bin/links -source” to get
ftp://ftp.perl.org/pub/CPAN/authors/01mailrc.txt.gz
ELinks: Connection timed out

Then you may have a check of whether you’re using proxy to get on the internet(run cpan > o conf init to re-configure cpan; later you should set /etc/wgetrc: http_proxy, ftp_proxy, use_proxy).

The following error messages occurred while running yum list or yum update on a centos/rhel host:

[root@test-centos ~]# yum list
Loaded plugins: rhnplugin, security
This system is not registered with ULN.
ULN support will be disabled.
Segmentation fault

As always, I did a strace on this:

[root@test-centos ~]# strace yum list
open(“/var/cache/yum/el5_ga_base/primary.xml.gz”, O_RDONLY) = 6
lseek(6, 0, SEEK_CUR) = 0
read(6, “\37\213\10\10\0\0\0\0\2\377/u01/basecamp/www/el5_”…, 8192) = 8192
— SIGSEGV (Segmentation fault) @ 0 (0) —
+++ killed by SIGSEGV +++

And here’s the error messages from /var/log/messages:

[root@test-centos ~]# tail /var/log/messages
Jan 6 07:07:44 test-centos kernel: yum[5951]: segfault at 3500000000 ip 000000350cc79e0a sp 00007fff05633b78 error 4 in libc-2.5.so[350cc00000+14e000]

After some googling, I found the yum “Segmentation fault” was caused by the conflict between zlib and yum. To resolve this problem, we need use the older version of zlib. Here’s the detailed steps:

[root@test-centos ~]# cd /usr/lib
[root@test-centos lib]# ls -l libz*
-rw-r–r– 1 root root 125206 Jul 9 07:40 libz.a
lrwxrwxrwx 1 root root 22 Aug 2 07:10 libz.so -> /usr/lib/libz.so.1.2.7
lrwxrwxrwx 1 root root 22 Aug 2 07:10 libz.so.1 -> /usr/lib/libz.so.1.2.7
-rwxr-xr-x 1 root root 75028 Jun 7 2007 libz.so.1.2.3
-rwxr-xr-x 1 root root 99161 Jul 9 07:40 libz.so.1.2.7

[root@test-centos lib]# rm libz.so libz.so.1
rm: remove symbolic link `libz.so’? y
rm: remove symbolic link `libz.so.1′? y
[root@test-centos lib]# ln -s libz.so.1.2.3 libz.so
[root@test-centos lib]# ln -s libz.so.1.2.3 libz.so.1

After these steps, you should now able to run yum commands without any issue.

Also, after using yum, you should change back zlib to the newer version, and here’s the steps:

[root@test-centos ~]# cd /usr/lib
[root@test-centos lib]# rm libz.so libz.so.1
rm: remove symbolic link `libz.so’? y
rm: remove symbolic link `libz.so.1′? y
[root@test-centos lib]# ln -s libz.so.1.2.7 libz.so
[root@test-centos lib]# ln -s libz.so.1.2.7 libz.so.1

On zfs storage 7000 series BUI, you may found the following statistic:

This may seem quite weird as you can see that, NFSv3(3052) + iSCSI(1021) is larger than Disk(1583). As iops for protocal NFSv3/iSCSI finally goes to Disk, so why iops for the two protocals is larger than Disk iops?

Here’s the reason:

Disk operations for NFSv3 and iSCSI are logical operations. These logical operations are then combined/optimized by sun zfs storage and then finally go to physical Disk operations.

PS:

You may also wonder why Disk iops can be as high as 1583. As this number is the sum of all disk controllers of the zfs storage system. Here’s some ballpark numbers for HDD iops:

• create iSCSI Target Group

Open zfs BUI, navigate through “Configuration” -> “SAN” -> “iSCSI Targets”. Then create new iSCSI Target by clicking plus sign. Give it an alias, and then select the Network interface(may be bond or LACP) you want to use. After creating this iSCSI target, drag the newly created target to the right side “iSCSI Target Groups” to create one iSCSI Target Group. You can give that iSCSI target group an name too. Note down the iSCSI Target Group’s iqn, this is important for later operations.(Network interfaces:use NAS interface)

• create iSCSI Initiator Group

Before going on the next step, we need first get the iSCSI initiator IQN for each hosts we want LUN allocated. On each host, execute the following command to get the iqn for iscsi on linux platform(You can edit this file before read it, for example, make iqn name ended with` hostname` so it’s easier for later operations on LUN<do a /etc/init.d/iscsi restart after your modification to initiatorname.iscsi>):

[root@test-host ~]# cat /etc/iscsi/initiatorname.iscsi
InitiatorName=<your host’s iqn name>

Now go back to zfs BUI, navigate through “Configuration” -> “SAN” -> “Initiators”. On the left side, click “iSCSI Initiators”, then click plus sign on it. Enter IQN you get from previos step and give it an name.(do this for each host you want iSCSI LUN allocated). After this, drag the newly created iSCSI initiator(s) from left side to form new iSCSI Initiator Groups on the right side(drag two items from the left to the same item on the right to form an group).

• create shared LUNs for iSCSI Initiator Group

After this, we need now create LUNs for iSCSI Initiator Group(so that shared lun can be allocated, for example, oracle RAC need shared storage). Click on diskette sign on the just created iSCSI Initiator Group,select the project you want the LUN allocated from, give it a name, and assign the volume size. Select the right target group you created before(you can also create a new one e.g. RAC in shares).

• scan shared LUNs from hosts

Now we’re going to operate on linux hosts. On each host you want iSCSI LUN allocated, do the following steps:

iscsiadm -m discovery -t st -p <ip address of your zfs storage>(use cluster’s ip if there’s zfs cluster)
iscsiadm -m node -T <variable, iSCSI Target Group iqn> -p <ip address of your zfs storage> -l
service iscsi restart

After these steps, you host(s) should now see the newly allocated iSCSI LUN(s), you can run fdisk -l to confirm.

Good luck!