In my earlier hands on lab post ( Hands on Lab – Replacing Failed Disks from ZFS Pools ( Simple / Mirrored / RaidZ )). I have explained the disk failure scenarios for ZPOOL  mirror and RaidZ volumes, and this post is just continuation to that post. And in this post I will showing the multiple disk failure scenarios for the RAIDZ2 and RAIDZ3, and the way to recover it.  

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Our Unixadmin, John from xyz company,  recently upgraded one of his server’s network interface card  from the old one with 100MB speed to a new one with 10Gig speed , and the reason is to improve the speed for the backup of the server. After the NIC Upgrade  john found that the server network performance was improved a little, but still the server is not able to utilize all the available network bandwidth. 

After a bit of investigation john realised that his server TCP window size has to be tuned  to utilize maximum network bandwidth available to the server.  In this post we will be discussing the procedure about “how john tuned the TCP window size  to increase his server network performance?”.

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We all know that storage is key requirement for any server environment and the requirement for storage is always dynamic in nature. When we talk about the cost, providing highly redundant storage to each server is most expensive task for any organization and no company want to waste the storage with fixed allocation to each server. And  Companies  had huge requirement for the applications which has capability to dynamically add or reduce storage to the servers without affecting the operations.  And this requirement increased the demand for user friendly and effective volume manager tools.  Both the Operating System Vendors and third party vendors started providing volume manager tools to the industry, and below are some of the major Volume manager tools in place right now:

• Solaris native Volume manager tools – SVM  and ZFS
• Linux  native volume manager tools – LVM
• Symantic native volume manager tools  – VxVM Full Story

Below procedure can be used to add a new NIS user when the passwd file is not in the /etc directory

Steps to Follow

The example below demonstrates how to add a user for NIS maps when the passwd file is not in the /etc directory.

The NIS directory is /etc/nisdir, where all the NIS maps reside.

Create a user in the /etc/passwd file. In this example, the new user is Johnl

Step 1.

Edit /etc/passwd to Add entry for the user

# vi /etc/passwd

Johnl:x:107:14:John l:/export/home/johnl:/bin/csh

Assign a password to the new user.

passwd johnl

Step 2:

Now run below command to create an entry in the shadow file

# pwconv

cat /etc/shadow file to see this entry in there.

johnl:dhXRywfkSELcE:10091::::::

Step 3:

Just copy the new entries to the /etc/nisdir/passwd file for passwd entry, and /etc/nisdir/shadow for shadow entry. To update the passwd map and push it to the slaves.

# make passwd

**NOTE**If you do not want this new user to be a local user, delete the entries in /etc/passwd and /etc/shadow.

The X4000 Family implements the ILOM – Integrated Lights Out Manager.  This is a combination of dedicated hardware and supporting software.

The Sun Fire X64 family of servers implement a technology called ILOM – Integrated Lights Out Manager where available. This is a combination of dedicated hardware and supporting software built on a service processor, integral to the platform.

Introduction

ILOM uses a hierarchical namespace.
It contains a predefined tree /SP namespace manages the ILOM. e.g. to manage users and clock settings. The SP namespace is generic over all platforms using the ILOM. /SYS namespace manages the host system. e.g. change the host state, read sensor information, and access other information for managed system hardware. The SYS namespace is unique to each platform. Full Story

Network connection problems include slow connections, as well as complete loss of connectivity. Factors that may cause slow connectivity include incorrectly configured domain name system (DNS) settings, inefficiently configured routing tables, inferior cabling, overloaded servers, and network congestion. The same set of factors, as well as power or server failures, may result in complete loss of connectivity.

To troubleshoot a network connectivity problem, you should first check for the presence of a physical connection. If the network interface card (NIC) link light on a system is off, it indicates that no physical connection exists. This may result from

the use of incompatible or damaged cables
loose or unplugged cables
loss of power to a network switch or router
Troubleshooting interface problems

Linux tools you can use to troubleshoot network interface problems include

• ifconfig -  Used to determine the status of NICs.Without arguments, this command returns the status of all active interfaces. If you specify the name of an interface, it returns the status only of that interface. With the -a argument, the command displays the status of all interfaces on a computer, including any that may be inactive. This is the basic syntax for using the ifconfig command: ifconfig [interface] [options]
• mii-tool – The mii-tool utility enables you to display and manipulate the media-independent interface status. In its simplest form, you can use it to display the status of the interface’s link. This is the basic syntax for using the mii-tool command: mii-tool [options] [interface]
• ethtool – The ethtool utility is a diagnostic tool that enables you to configure and diagnose problems with NICs. However, not all NICs support its use. This is the basic syntax for using the ethtool command: ethtool [options] interface Full Story