Lik`s forum

This plugin checks all RAID volumes (hardware and software) that can be identified.

Supported RAIDs that can be checked:

Adaptec AAC RAID via aaccli or afacli or arcconf
Adaptec AAC RAID via aaccli or afacli or arcconf
AIX software RAID via lsvg
HP/Compaq Smart Array via cciss_vol_status (hpsa supported too)
HP Smart Array Controllers and MSA Controllers via hpacucli and hpssacli
HP Smart Array (MSA1500) via serial line
Linux 3ware SATA RAID via tw_cli ...

To clear a vty (ssh/telnet) connection on Cisco router we have to clear the specific line.
To find this line we can use the following command:

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router#who

For example a router has a vty connection from a host with ip 10.10.10.10 on line 3:
router#who
Line User Host(s) Idle Location
2 vty 1 idle 00:00:02 10.11.10.11
3 vty 2 root idle 00:00:06 10.10.10.10
* 5 vty 4 admin idle 00:00:00 192.168.17.67

Interface User Mode Idle ...

http://www.linux-kvm.org/page/Management_Tools

fio is an I/O tool meant to be used both for benchmark and stress/hardware verification. It has support for 13 different types of I/O engines (sync, mmap, libaio, posixaio, SG v3, splice, null, network, syslet, guasi, solarisaio, and more), I/O priorities (for newer Linux kernels), rate I/O, forked or threaded jobs, and much more. It can work on block devices as well as files. fio accepts job descriptions in a simple-to-understand text format. Several example ...

Good description of Kernel Samepage Merging (KSM) feature:
http://www.ibm.com/developerworks/linux/library/l-kernel-shared-memory/index.html
https://github.com/torvalds/linux/blob/master/Documentation/vm/ksm.txt

Warning: The resulting partition is not properly aligned for best performance.

In order to align partition with parted you can use --align option. Valid alignment types are:

none - Use the minimum alignment allowed by the disk type.
cylinder - Align partitions to cylinders.
minimal - Use minimum alignment as given by the disk topology information. This and the opt value will use layout information provided by the disk to align the logical partition table ...

http://www.modsecurity.org/projects/modsecurity/nginx/index.html

Everytime you install or update packages with yum on Centos5/RHEL5, it tries to install both x86_64 and i386 versions of the package if both are available.
This problem arise only on Centos5 because yum defaults to:

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multilib_policy=all

what means install all available architectures of package. For example, if you are running 64bit system, yum will first try to install package.x86_64, if it`s not available yum will fall back to i386 and noarch.
This was changed ...

By default linux distributions (not only) expect that default gateway IP address belongs to configured subnetwork on the interface and is not a broadcast address.
As a result we will receive the following error trying to define gateway outside of configured network:
# ifconfig eth0
eth0 Link encap:Ethernet HWaddr 00:16:3E:29:5A:82
inet addr:10.10.10.10 Bcast:10.10.10.15 Mask:255.255.255.248
inet6 addr: fe80::216:3eff:fe29:5a82/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:2522216 errors:0 dropped:0 overruns:0 frame:0
TX packets:61813 errors:0 dropped:0 overruns:0 ...

vzubc − CLI utilitu to show user beancounters (UBC) in a human-readable format. It is a part of vzctl since 3.0.27 version.

# vzubc -h
Usage: vzubc [option ...] [<ctid> ...]

-w, --watch:
Run itself under watch(1) (a la top mode, Ctrl-C to exit).
-wd: show differences between runs
-wn <time>: refresh every <time> seconds
-q, --quiet:
Quiet mode (only show beancounters with fails and close to limits).
-qh <ratio>: quiet threshold for held/limit ratio ...