Note: This is from http://www.richweb.com/cpu_info

A hyperthreaded processor has the same number of function units as an older, non-hyperthreaded processor. It just has two execution contexts, so it can maybe achieve better function unit utilization by letting more than one program execute concurrently. On the other hand, if you’re running two programs which compete for the same function units, there is no advantage at all to having both running “concurrently.” When one is running, the other is necessarily waiting on the same function units.

A dual core processor literally has two times as many function units as a single-core processor, and can really run two programs concurrently, with no competition for function units.

A dual core processor is built so that both cores share the same level 2 cache. A dual processor (separate physical cpus) system differs in that each cpu will have its own level 2 cache. This may sound like an advantage, and in some situations it can be but in many cases new research and testing shows that the shared cache can be faster when the cpus are sharing the same or very similar tasks.

In general Hyperthreading is considered older technology and is no longer supported in newer cpus. Hyperthreading can provide a marginal (10%) for some server workloads like mysql, but dual core technology has essentially replaced hyperthreading in newer systems.

A dual core cpu running at 3.0Ghz should be faster then a dual cpu (separate core) system running at 3.0Ghz due to the ability to share the cache at higher bus speeds.

The examples below details how we determine what kind of cpu(s) are present.

The kernel data Linux exposes in /proc/cpuinfo will show each logical cpu with a unique processor number. A logical cpu can be a hyperthreading sibling, a shared core in a dual or quad core, or a separate physical cpu. We must look at the siblings, cpu cores and core id to tell the difference.

If the number of cores = the number of siblings for a given physical processor, then hyperthreading is OFF.

/bin/cat /proc/cpuinfo | /bin/egrep ‘processor|model name|cache size|core|sibling|physical’

Example 1: Single processor, 1 core, no Hyperthreading

processor	: 0
model name	: AMD Duron(tm) processor
cache size	: 64 KB

Example 2: Single processor, 1 core, Hyperthreading is enabled.

Notice how we have 2 siblings, but only 1 core. The physical cpu id is the same for both: 0.

processor	: 0
model name	: Intel(R) Pentium(R) 4 CPU 2.80GHz
cache size	: 1024 KB
physical id	: 0
siblings	: 2
core id		: 0
cpu cores	: 1
processor	: 1
model name	: Intel(R) Pentium(R) 4 CPU 2.80GHz
cache size	: 1024 KB
physical id	: 0
siblings	: 2
core id		: 0
cpu cores	: 1

Example 3. Single socket Quad Core

Notice how each processor has its own core id. The number of siblings matches the number of cores so there are no Hyperthreading siblings. Also notice the huge l2 cache – 6 MB. That makes sense though, when considering 4 cores share that l2 cache.

processor	: 0
model name	: Intel(R) Xeon(R) CPU           E5410  @ 2.33GHz
cache size	: 6144 KB
physical id	: 0
siblings	: 4
core id		: 0
cpu cores	: 4
processor	: 1
model name	: Intel(R) Xeon(R) CPU           E5410  @ 2.33GHz
cache size	: 6144 KB
physical id	: 0
siblings	: 4
core id		: 1
cpu cores	: 4
processor	: 2
model name	: Intel(R) Xeon(R) CPU           E5410  @ 2.33GHz
cache size	: 6144 KB
physical id	: 0
siblings	: 4
core id		: 2
cpu cores	: 4
processor	: 3
model name	: Intel(R) Xeon(R) CPU           E5410  @ 2.33GHz
cache size	: 6144 KB
physical id	: 0
siblings	: 4
core id		: 3
cpu cores	: 4

Example 3a. Single socket Dual Core

Again, each processor has its own core so this is a dual core system.

processor	: 0
model name	: Intel(R) Pentium(R) D CPU 3.00GHz
cache size	: 2048 KB
physical id	: 0
siblings	: 2
core id		: 0
cpu cores	: 2
processor	: 1
model name	: Intel(R) Pentium(R) D CPU 3.00GHz
cache size	: 2048 KB
physical id	: 0
siblings	: 2
core id		: 1
cpu cores	: 2

Example 4. Dual Single core CPU, Hyperthreading ENABLED

This example shows that processer 0 and 2 share the same physical cpu and 1 and 3 share the same physical cpu. The number of siblings is twice the number of cores, which is another clue that this is a system with hyperthreading enabled.

processor	: 0
model name	: Intel(R) Xeon(TM) CPU 3.60GHz
cache size	: 1024 KB
physical id	: 0
siblings	: 2
core id		: 0
cpu cores	: 1
processor	: 1
model name	: Intel(R) Xeon(TM) CPU 3.60GHz
cache size	: 1024 KB
physical id	: 3
siblings	: 2
core id		: 0
cpu cores	: 1
processor	: 2
model name	: Intel(R) Xeon(TM) CPU 3.60GHz
cache size	: 1024 KB
physical id	: 0
siblings	: 2
core id		: 0
cpu cores	: 1
processor	: 3
model name	: Intel(R) Xeon(TM) CPU 3.60GHz
cache size	: 1024 KB
physical id	: 3
siblings	: 2
core id		: 0
cpu cores	: 1

Example 5. Dual CPU Dual Core No hyperthreading

Of the 5 examples this should be the most capable system processor-wise. There are a total of 4 cores; 2 cores in 2 separate socketed physical cpus. Each core shares the 4MB cache with its sibling core. The higher clock rate (3.0 Ghz vs 2.3Ghz) should offer slightly better performance than example 3.

processor	: 0
model name	: Intel(R) Xeon(R) CPU            5160  @ 3.00GHz
cache size	: 4096 KB
physical id	: 0
siblings	: 2
core id		: 0
cpu cores	: 2
processor	: 1
model name	: Intel(R) Xeon(R) CPU            5160  @ 3.00GHz
cache size	: 4096 KB
physical id	: 0
siblings	: 2
core id		: 1
cpu cores	: 2
processor	: 2
model name	: Intel(R) Xeon(R) CPU            5160  @ 3.00GHz
cache size	: 4096 KB
physical id	: 3
siblings	: 2
core id		: 0
cpu cores	: 2
processor	: 3
model name	: Intel(R) Xeon(R) CPU            5160  @ 3.00GHz
cache size	: 4096 KB
physical id	: 3
siblings	: 2
core id		: 1
cpu cores	: 2

PS:
For explanation about flags in linux /proc/cpuinfo, you can refer to following:
http://blog.incase.de/index.php/cpu-feature-flags-and-their-meanings/

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

This article is going to talk about zfs storage 7320 monitoring using net-snmp and mrtg. Although the monitored system is sun zfs storage 7320, you’ll find the main idea of this article can be applied to many different system monitoring, including but not limited to cpu usage/network/bandwidth/disk/temperature of cisco switches, other linux systems and even windows systems.

As net-snmp extending agent functionality is not supported on sun zfs storage 7320 which is solaris 11 express system, so I’m going to monitor sun zfs storage through using of one linux snmp client by writing monitoring scripts on that linux client rather than on zfs itself.

Now, here goes the steps:

Part 1 – set up snmp client and mrtg on a linux host

yum -y install gcc-* gd-* libpng-* zlib-* httpd
yum -y install net-snmp* net-snmp-libs lm_sensors lm_sensors-devel
yum -y install mrtg
cp /etc/snmp/snmpd.conf{,.bak}
echo “rocommunity public” > /etc/snmp/snmpd.conf
mkdir -p /etc/mrtg
chkconfig –level 2345 snmpd on
service snmpd start

Ensure snmpd is listening:

netstat -tunlp |grep snmp
tcp 0 0 127.0.0.1:199 0.0.0.0:* LISTEN 26427/snmpd
udp 0 0 0.0.0.0:161 0.0.0.0:* 26427/snmpd

And let’s have a test to make sure snmp client is working as expected:

[root@test-centos mrtg]# snmpwalk -v2c -c public localhost interface
IF-MIB::ifNumber.0 = INTEGER: 4
IF-MIB::ifIndex.1 = INTEGER: 1
IF-MIB::ifIndex.2 = INTEGER: 2
IF-MIB::ifIndex.3 = INTEGER: 3
IF-MIB::ifIndex.4 = INTEGER: 4
IF-MIB::ifDescr.1 = STRING: lo
IF-MIB::ifDescr.2 = STRING: eth0
IF-MIB::ifDescr.3 = STRING: eth1
……
……

Now it’s time to configure mrtg on linux:

[root@test-centos mrtg]# cat /etc/httpd/conf.d/mrtg.conf
Alias /mrtg /var/www/mrtg
<Location /mrtg>
Order deny,allow
Allow from all
</Location>

Now, do a httpd restart:

[root@test-centos ~]# apachectl restart

Part 2 – configure snmp on SUN zfs storage 7320 web UI

Log on SUN zfs storage 7320 web UI, navigate through “Configuration” -> “SNMP”, and configure as the following:

After this, you’ll need enable/restart SNMP service on zfs.
Now do a snmpwalk from snmp linux client to SUN zfs storage:

[root@test-centos ~]# snmpwalk -v2c -c public test-zfs-host interface
IF-MIB::ifNumber.0 = INTEGER: 6
IF-MIB::ifIndex.1 = INTEGER: 1
IF-MIB::ifIndex.4 = INTEGER: 4
IF-MIB::ifIndex.5 = INTEGER: 5
IF-MIB::ifIndex.6 = INTEGER: 6
IF-MIB::ifIndex.7 = INTEGER: 7
IF-MIB::ifIndex.8 = INTEGER: 8
IF-MIB::ifDescr.1 = STRING: lo0
……
……

• Part 3 – extending snmp mibs/oids on snmp client(the linux host)

As stated at the beginning of this article, net-snmp extending agent functionality is not supported on sun zfs storage 7320. So I’m going to monitor sun zfs storage through using of one linux snmp client by writing monitoring scripts on that linux client rather than on zfs itself.

To avoid ssh asking for password when connecting from the linux host, you need add the linux host’s pubkey to sun zfs storage:
On snmp Linux client:

[root@test-centos ~]# ssh-keygen -t rsa #if you already have pubkey, skip this step
[root@test-centos ~]# cat /root/.ssh/id_rsa.pub |awk ‘{print $2}’
AAAAB3NzaC1yc2EAAAABIwAAAQEAxYd97A/V5RwdkfzbkmYBqF189pTLOlbYt0dZzO395dfU0Sp/Ykrk+sOJO0bJZEtytuTcCz/bVutWB7vLzeQPxIToRUQnZX7ZoMsjyaFk3LhtAgFhYIycOw2FQL8Qvb5yMBASB2/KthsqaiNqOP/2Vy5e0aCFFIV5DlKQTp/3eceSMq8kTx+e801lZow++yT70rp3p+5WtriN/NKYI0B3cpSQY/36D/TcOF9v5IaqQokp/mLRoc1MLOhN0sy0ipCdT+0bbkZ4Lh8bEeQO48UGKEOnYrYto33tay4mZk8HPWFK4w/TQGxBLthiuPQ4oZzG3gVpQUS4GRwI9zZoGtgELQ==

On Sun zfs storage:
Click “Configuration”, then add the snmp client’s public key(ensure RSA is selected):

Do a ssh connection from snmp linux client to the sun zfs storage host, it should now not asking for password.(ensure to do this, as there’s possibility that sun zfs’s key is not on the linux client as you may never have connected from that linux client to the sun zfs storage system)

Now we’re to the most important part. Assume we want to monitoring space usage on the SUN zfs storage system, to do this, you’ll need do the following on the snmp linux client:

[root@test-centos mrtg]# cat /etc/snmp/snmpd.conf
rocommunity public
extend .1.3.6.1.4.1.2021.31 zfs-test-zfs-host-total /bin/bash /var/tmp/mrtg/zfs-test-zfs-host-total.sh
extend .1.3.6.1.4.1.2021.32 zfs-test-zfs-host-used /bin/bash /var/tmp/mrtg/zfs-test-zfs-host-used.sh

[root@test-centos ~]# cat /var/tmp/mrtg/zfs-test-zfs-host-used.sh
#!/bin/bash
_used=`ssh test-zfs-host “status ls”|grep Used|awk ‘{print gensub(‘/T/’,”",”g”,$2)}’`
echo $_used;

[root@test-centos ~]# cat /var/tmp/mrtg/zfs-test-zfs-host-total.sh
_used=`ssh test-zfs-host “status ls”|grep Used|awk ‘{print gensub(‘/T/’,”",”g”,$2)}’` #I trimed ‘T’, you may need modify this to meet your environment
_avail=`ssh test-zfs-host “status ls”|grep Avail|awk ‘{print gensub(‘/T/’,”",”g”,$2)}’` #I trimed ‘T’, you may need modify this to meet your environment
_all=`echo $_used + $_avail|bc`
echo $_all;

[root@test-centos ~]# chmod +x /var/tmp/mrtg/zfs-test-zfs-host-used.sh
[root@test-centos ~]# chmod +x /var/tmp/mrtg/zfs-test-zfs-host-total.sh

Now, let’s do a snmp restart on snmp linux client and then test the newly added OIDs:

[root@test-centos ~]# service snmpd restart

[root@test-centos ~]# snmpwalk -v2c -c public localhost .1.3.6.1.4.1.2021.32
UCD-SNMP-MIB::ucdavis.32.1.0 = INTEGER: 1
UCD-SNMP-MIB::ucdavis.32.2.1.2.19.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.117.115.101.100 = STRING: “/bin/bash”
UCD-SNMP-MIB::ucdavis.32.2.1.3.19.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.117.115.101.100 = STRING: “/var/tmp/mrtg/zfs-test-zfs-host-used.sh”
UCD-SNMP-MIB::ucdavis.32.2.1.4.19.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.117.115.101.100 = “”
UCD-SNMP-MIB::ucdavis.32.2.1.5.19.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.117.115.101.100 = INTEGER: 5
UCD-SNMP-MIB::ucdavis.32.2.1.6.19.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.117.115.101.100 = INTEGER: 1
UCD-SNMP-MIB::ucdavis.32.2.1.7.19.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.117.115.101.100 = INTEGER: 1
UCD-SNMP-MIB::ucdavis.32.2.1.20.19.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.117.115.101.100 = INTEGER: 4
UCD-SNMP-MIB::ucdavis.32.2.1.21.19.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.117.115.101.100 = INTEGER: 1
UCD-SNMP-MIB::ucdavis.32.3.1.1.19.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.117.115.101.100 = STRING: “9.31″
UCD-SNMP-MIB::ucdavis.32.3.1.2.19.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.117.115.101.100 = STRING: “9.31″
UCD-SNMP-MIB::ucdavis.32.3.1.3.19.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.117.115.101.100 = INTEGER: 1
UCD-SNMP-MIB::ucdavis.32.3.1.4.19.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.117.115.101.100 = INTEGER: 0
UCD-SNMP-MIB::ucdavis.32.4.1.2.19.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.117.115.101.100.1 = STRING: “9.31″
[root@test-centos ~]# snmpwalk -v2c -c public localhost .1.3.6.1.4.1.2021.31
UCD-SNMP-MIB::ucdavis.31.1.0 = INTEGER: 1
UCD-SNMP-MIB::ucdavis.31.2.1.2.20.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.116.111.116.97.108 = STRING: “/bin/bash”
UCD-SNMP-MIB::ucdavis.31.2.1.3.20.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.116.111.116.97.108 = STRING: “/var/tmp/mrtg/zfs-test-zfs-host-total.sh”
UCD-SNMP-MIB::ucdavis.31.2.1.4.20.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.116.111.116.97.108 = “”
UCD-SNMP-MIB::ucdavis.31.2.1.5.20.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.116.111.116.97.108 = INTEGER: 5
UCD-SNMP-MIB::ucdavis.31.2.1.6.20.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.116.111.116.97.108 = INTEGER: 1
UCD-SNMP-MIB::ucdavis.31.2.1.7.20.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.116.111.116.97.108 = INTEGER: 1
UCD-SNMP-MIB::ucdavis.31.2.1.20.20.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.116.111.116.97.108 = INTEGER: 4
UCD-SNMP-MIB::ucdavis.31.2.1.21.20.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.116.111.116.97.108 = INTEGER: 1
UCD-SNMP-MIB::ucdavis.31.3.1.1.20.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.116.111.116.97.108 = STRING: “16.32″
UCD-SNMP-MIB::ucdavis.31.3.1.2.20.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.116.111.116.97.108 = STRING: “16.32″
UCD-SNMP-MIB::ucdavis.31.3.1.3.20.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.116.111.116.97.108 = INTEGER: 1
UCD-SNMP-MIB::ucdavis.31.3.1.4.20.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.116.111.116.97.108 = INTEGER: 0
UCD-SNMP-MIB::ucdavis.31.4.1.2.20.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.116.111.116.97.108.1 = STRING: “16.32″

From the output, we can see that OIDs UCD-SNMP-MIB::ucdavis.32.3.1.1.19.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.117.115.101.100 (used space) and UCD-SNMP-MIB::ucdavis.31.3.1.1.20.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.116.111.116.97.108 (total space) are the two OIDs we want.

• Part 4 – do the mrtg drawing

As we got the OIDs we want, it’s now easier for us to do the mrtg drawing. On the snmp linux host, do the following steps:

[root@test-centos ~]# cat /etc/mrtg/test-zfs-host.cfg
#LoadMIBs: /usr/share/snmp/mibs/UCD-SNMP-MIB.txt,/usr/share/snmp/mibs/TCP-MIB.txt
workdir: /var/www/mrtg/
Title[zfs_space_test-zfs-host]: Percentage used space on zfs
PageTop[zfs_space_test-zfs-host]: <h1>Percentage used space on zfs</h1>
Target[zfs_space_test-zfs-host]: .1.3.6.1.4.1.2021.32.3.1.1.19.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.117.115.101.100&.1.3.6.1.4.1.2021.31.3.1.1.20.122.102.115.45.115.108.99.101.49.48.115.110.48.49.45.116.111.116.97.108:public@localhost
Options[zfs_space_test-zfs-host]: growright,gauge,transparent,nopercent
Unscaled[zfs_space_test-zfs-host]: ymwd
MaxBytes[zfs_space_test-zfs-host]: 100
YLegend[zfs_space_test-zfs-host]: UsedSpace %
ShortLegend[zfs_space_test-zfs-host]: T
LegendI[zfs_space_test-zfs-host]: Used
LegendO[zfs_space_test-zfs-host]: Total
Legend1[zfs_space_test-zfs-host]: Percentage used space on zfs
Legend2[zfs_space_test-zfs-host]: Percentage all space on zfs

PS:
You need replace “UCD-SNMP-MIB::ucdavis” with .1.3.6.1.4.1.2021 or you’ll get error messages like the following:

[root@test-centos ~]# env LANG=C TZ=Asia/Shanghai /usr/bin/mrtg /etc/mrtg/test-zfs-host.cfg
Argument “v4only” isn’t numeric in int at /usr/bin/../lib64/mrtg2/SNMP_Session.pm line 183.
backoff (v4only) must be a number >= 1.0 at /usr/bin/../lib64/mrtg2/SNMP_util.pm line 465

Let’s continue:

[root@test-centos ~]# env LANG=C TZ=Asia/Shanghai /usr/bin/mrtg /etc/mrtg/test-zfs-host.cfg
24-12-2012 01:46:41, Rateup WARNING: /usr/bin/rateup could not read the primary log file for zfs_space_test-zfs-host
24-12-2012 01:46:41, Rateup WARNING: /usr/bin/rateup The backup log file for zfs_space_test-zfs-host was invalid as well
24-12-2012 01:46:41, Rateup WARNING: /usr/bin/rateup Can’t remove zfs_space_test-zfs-host.old updating log file
24-12-2012 01:46:41, Rateup WARNING: /usr/bin/rateup Can’t rename zfs_space_test-zfs-host.log to zfs_space_test-zfs-host.old updating log file

[root@test-centos ~]# env LANG=C TZ=Asia/Shanghai /usr/bin/mrtg /etc/mrtg/test-zfs-host.cfg
24-12-2012 01:46:46, Rateup WARNING: /usr/bin/rateup Can’t remove zfs_space_test-zfs-host.old updating log file

[root@test-centos ~]# env LANG=C TZ=Asia/Shanghai /usr/bin/mrtg /etc/mrtg/test-zfs-host.cfg

[root@test-centos ~]# indexmaker –output=/var/www/mrtg/index.html /etc/mrtg/test-zfs-host.cfg

Now add cronjob:

0-59/5 * * * * env LANG=C TZ=Asia/Shanghai /usr/bin/mrtg /etc/mrtg/test-zfs-host.cfg

Visit http://<your linux box’s ip address>/mrtg/ to get the GUI result(you’ll wait 5 minutes for the initial result, be patient!)

• Part 5 – troubleshooting

• If you met error messages like the following:

[root@test-centos ~]# env LANG=C TZ=Asia/Shanghai /usr/bin/mrtg /etc/mrtg/test-zfs-host.cfg
Argument “v4only” isn’t numeric in int at /usr/bin/../lib64/mrtg2/SNMP_Session.pm line 183.
backoff (v4only) must be a number >= 1.0 at /usr/bin/../lib64/mrtg2/SNMP_util.pm line 465

That’s because you’re using OIDs/MIBs alias rather than number. Change alias to number, i.e. change UCD-SNMP-MIB::ucdavis to .1.3.6.1.4.1.2021, and then re-check.

• If you met error messages like the following:

• If you met error messages like the following:

[root@test-centos mrtg]# env LANG=C TZ=Asia/Shanghai /usr/bin/mrtg /etc/mrtg/test-zfs-host.cfg
SNMP Error:
Received SNMP response with error code
error status: noSuchName
index 2 (OID: 1.3.6.1.4.1.2021.44)
SNMPv1_Session (remote host: “localhost” [127.0.0.1].161)
community: “public”
request ID: 1786815468
PDU bufsize: 8000 bytes
timeout: 2s
retries: 5
backoff: 1)
at /usr/bin/../lib64/mrtg2/SNMP_util.pm line 490
SNMPGET Problem for .1.3.6.1.4.1.2021.44 .1.3.6.1.4.1.2021.44 sysUptime sysName on public@localhost::::::v4only
at /usr/bin/mrtg line 2035
SNMP Error:
Received SNMP response with error code
error status: noSuchName
index 2 (OID: 1.3.6.1.4.1.2021.45)
SNMPv1_Session (remote host: “localhost” [127.0.0.1].161)
community: “public”
request ID: 1786815469
PDU bufsize: 8000 bytes
timeout: 2s
retries: 5
backoff: 1)
at /usr/bin/../lib64/mrtg2/SNMP_util.pm line 490
SNMPGET Problem for .1.3.6.1.4.1.2021.45 .1.3.6.1.4.1.2021.45 sysUptime sysName on public@localhost::::::v4only
at /usr/bin/mrtg line 2035
Monday, 24 December 2012 at 14:41: ERROR: Target[zfs_space_test-zfs-host][_IN_] ‘( $target->[0]{$mode} ) * 10000 / ( $target->[1]{$mode} )’ (warn): Use of uninitialized value in division (/) at (eval 16) line 1.
Monday, 24 December 2012 at 14:41: ERROR: Target[zfs_space_test-zfs-host][_OUT_] ‘( $target->[0]{$mode} ) * 10000 / ( $target->[1]{$mode} )’ (warn): Use of uninitialized value in division (/) at (eval 17) line 1.

Then one possible culprit is that new net-snmp stop supporting “exec”, use “extend” instead and re-try.

Note that you can also use “snmpd -f -Le” to check error messages related to snmpd.

PS:
Here’s more links from where you can read more about net-snmp/mrtg:

1. net-snmp FAQ http://www.net-snmp.org/FAQ.html
2. mrtg configuration opstions http://oss.oetiker.ch/mrtg/doc/mrtg-reference.en.html
3. SUN zfs storage SNMP – http://docs.oracle.com/cd/E22471_01/html/820-4167/configuration__services__snmp.html
4. net-snmp extending agent functionality – http://linux.die.net/man/5/snmpd.conf (search for ‘extending agent functionality’ on this page)
5. Now here’s the image of the baby(click on it to see the larger one:

Some iLom software(for example oracle iLom) use java jnlp applet(java console) to open remote console of the server. To use this functionality, you need java plugin on firefox installed. Here’s the detailed steps:

• Update firefox: yum update firefox, please note that you better remove firefox 64 bit version and use 32 version ones(reason followed). After this, you’ll have firefox 10 on the system.

@namespace url(http://www.w3.org/1999/xhtml);
#mainpage {
visibility: visible !important;
}

• Install JRE 6: Go to http://www.oracle.com/technetwork/java/javase/downloads/jre6u37-downloads-1859589.html and download jre-6u37-linux-i586-rpm.bin. After that, install the package on the system using rpm -Uvh.(make sure NOT to download 64bits version, as java console only support 32bits java plugin)

• Make java plugin available to firefox: If you are planning to run firefox under root, do the following steps:

mkdir -p /root/.mozilla/plugins/

ln -s /usr/java/jre1.6.0_37/lib/libnpjp2.so /root/.mozilla/plugins/

PS:

if you’ve installed java plugin before, you’ll first need remove it.

• Now restart firefox, and go to about:plugins, you’ll see java plugin enabled. Open java console and enjoy!(select javaWS if prompted)

If you can log on the host but the home directory failed mouting with the following error message:

Could not chdir to home directory /home/xxx: No such file or directory

Then one method you can try is that:

1. Ensure the home directory for your username exists on the exported NFS server
2. Append /etc/auto_home on the host with text like the following:<username> <NFS server>:/export/home/&  #this assume the exported home directory is on /export/home, your environment may varies
3. At last, ensure automount is running on the host and then try log on again. You should now able to mount your home directory.

There’s a weird incident occurred on a linux box. The linux box turned not responsible to ping or ssh, although from ifconfig and /proc/net/bonding/bond0 file, the system said it’s running ok. After some google work, I found that the issue may related to the NIC driver. I tried bring down/bring up NICs one by one, but got error:

Bringing up loopback interface bond0: bnx2i: dev eth0 does not support iscsi

bnx2i: iSCSI not supported, dev=eth0

bonding: no command found in slaves file for bond bond0. Use +ifname or -ifname

At last, I tried restart the whole network i.e. /etc/init.d/network restart. And that did the trick, the networking was then running ok and can ping/ssh to it without problem.