1. Network does not start due to “Device not managed by Network-Manager” error.

2. Frame errors in network Interface – What does it mean?

3. Network restart throws the error “some other host already uses address”

4. How to map the physical network interface corresponds to which ethX device?

5. How do I add/delete additional Logical IP addresses to a network interface in RHEL6?

6. Network interface does not come up after reboot; must be manually brought up with ifup

7. How do I run a script or program immediately after my network interface goes up?

8. How to Configure more than one default gateway for a multi-home system ( i.e. had two or more separate Network Interface Cards)?

9. What is the “ethtool” command and how can I use it to obtain information about my network devices and interfaces?

 10.  How do I set up VLAN (802.1q) tagging on a network interface ?.

11. How can I route network traffic such that the packets go out via the same interface they came in?

12. Setting persistent network interfaces using udev in Red Hat Enterprise Linux 6

13. Network interface failes due to the delay in bringing up the link from switch side.

14. How to configure network interfaces, after fresh installation.They are not available after reboot?

15. Why does network interface show “rx_errors” in ifconfig output or what is rx_crc_errors ?

16. How to calculate right Prefix for the Netmask to configure in the ifcfg-eth* files, usin ipcalc?

17. Connecting 2 network interfaces on the same subnet.

18. How to enable jumbo frames for network interfaces in Red Hat Enterprise Linux?

19. Loopback interface lo deleted with system-config-network

Read Full

1. How to re-install GRUB boot loader on the Master Boot Record(MBR) in rescue mode?

2. How to pause the boot process at GRUB menu to select a kernel ?

3.  How to give  customized names  for available kernels in the GRUB menu,  for easy identification of purpose ?

  Read Full

1. How do I reduce LVM logical volume in Red Hat Enterprise linux?

2. What is the difference between “Linux” and “Linux LVM” partition types?

3. How do we Log all LVM commands, that we execute on the machine?

4. How do I create LVM-backed raw devices with udev in RHEL6?

5. What is optimal stripe count for better performance in LVM?

6. LVM commands are failing with this error: Can’t open exclusively. Mounted filesystem?

7. Recommended region size for mirrored lvm volumes ?

8. Recreating a partition table that was accidentally deleted that contains an LVM Physical Volume on Red Hat Enterprise Linux?

9.  LVM2 volume group in partial mode with physical volumes marked missing even though they are available in RHEL

10. Mount LVM partitions on SAN storage connected to a newly-built server?

11. How to Grow an LVM Physical Volume after resizing the disk?

12. Delete a LVM partition

13. Restore a volume group in Red Hat Enterprise Linux if one of the physical volumes that constitutes the volume group has failed.

14. Logical Volume Manager (LVM) snapshot and how do we use it?

15. How do we Create New LVM volume from a LVM snapshot?

16. How can I boot from an LVM snapshot on Red Hat Enterprise Linux? 

17.How much memory is consumed by an LVM snapshot?

Read Full

 1. How Do I Load a Kernel Module on System Start-up? ( RHEL5/6)

2. What is the technical differences between a normal SMP kernel and a hugemem kernel?

3. How to specify a ‘default’ boot kernel type for a RHEL?

4. How to update RHEL kernel ?

5. How do I exclude updating the kernel or other packages in RHEL 5/6 while updating system via yum ?

6. How do I boot using an alternate/previous kernel?

7. How do I modify GRUB (grub.conf) to use a new kernel?

8. How to downgrade a kernel?

9. How to set kernel parameters in sysctl.conf file permanently?

10. What is kernel-firmware?

11. How to increase the kernel ring buffer size?

12. How do I blacklist a kernel module to prevent it loading automatically?

13. What is the proper method to remove old kernels from a Red Hat Enterprise Linux system?

14. What are the kernel parameter for inter-process communication?

15. Root cause analysis for kernel panic on RHEL?

16. How can the runtime values of kernel module parameters be displayed in RHEL5?

17. The /boot directory is getting full, how do I remove old kernels?

18. What are the kernel module utilities in Red Hat Enterprise Linux?

  Read Full

During the past two to three years,  many organisations started migrating their Server storage from Old legacy SAN devices ( e.g. EMC Clariion )  to new  powerful SAN storage ( e.g. EMC Symetrix VMAX) because of the low performance and maintenance costs involved with legacy storage.  Depending on the budget allocated for the Storage Migration projects, some organisations  prefer the migration by “direct storage level data replication  using expensive migration tools”,  while the other companies ( who are with limited budget) prefer to do the migrations by host level data replication. In the later method,  the success rate of the migration project directly depends on the skill level and expertise of the  unix administrator who is implementing the migration project.  I believe this hands-on post will give some idea for the solaris admins whoever responsible for the Storage migrations. Before going to this post you might want to refer this post for the pre-planning tasks.

 

 

 

  Read Full

This is second part of my earlier post “Linux Samba Server integration with Windows Active Directory”. In this post I will be  showing you the procedure to configure the Samba servers with two different shares, one share is having access to only specific samba user whereas other share was given access to all Active directory users of the domain “gurkulindia.com”

Why someone need to integrate the samba server to windows Active Directory?

In general we setup user access permissions on every samba share,  in traditional unix environment every user will have a unix login so it’s easy to give permission to either a specific user or group of users. But when we are using samba in heterogeneous environment where the samba shares are required for both unix users and windows users, we need to create a separate Unix account for every windows user, which is  not only a repetitive task but also highly complex to setup permissions as per their windows groups.

By integrating the Samba Server with Active Directory, we can simplify the samba share access to windows users.  Based on their Windows group membership every windows users can access the samba share without having  a special unix account created.

Read Full