SHIFT-WIKI - Sjoerd Hooft's InFormation Technology
This WIKI is my personal documentation blog. Please enjoy it and feel free to reach out through blue sky if you have a question, remark, improvement or observation. See below for the latest additions, or use the search or tags to browse for content.
Red Hat Boot Process
Summary: Explaining the Red Hat Boot process.
Date: Around 2014
Refactor: 29 March 2025: Checked links and formatting.
Red Hat has a 4 stage boot process:
- BIOS
- GRUB
- Kernel
- Init
AIX Memory
Summary: ALthough AIX is by now on version 7.3 I find these old pages so fascinating I decided to keep them. On this page I'll show you how to work with AIX memory. This page is for AIX 5.3 and AIX 6.1.
Date: Between 2010-2013
Refactor: 21 December 2024: Checked formatting.
Red Hat LUN Alignment
Summary: How to check if your disks on Red Hat are aligned with the underlying SAN LUNs.
Date: Around 2014
Refactor: 29 March 2025: Checked links and formatting.
Red Hat Enterprise Linux 6 should align it's disk correctly to the underlying LUNs but to make sure you should always check:
First, check which partitions are seen by the kernel:
[root@redhatbox ~]# cat /proc/partitions major minor #blocks name 8 0 20971520 sda 8 1 204800 sda1 8 2 20765696 sda2 253 0 2097152 dm-0 253 1 5242880 dm-1 253 2 5242880 dm-2 253 3 5242880 dm-3 253 4 2097152 dm-4
Then, check whether the partitions are aligned or not:
[root@redhatbox ~]# fdisk -lu /dev/sda Disk /dev/sda: 21.5 GB, 21474836480 bytes 64 heads, 32 sectors/track, 20480 cylinders, total 41943040 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000c0750 Device Boot Start End Blocks Id System /dev/sda1 * 2048 411647 204800 83 Linux Partition 1 does not end on cylinder boundary. /dev/sda2 411648 41943039 20765696 8e Linux LVM Partition 2 does not end on cylinder boundary.
The start sector should be cleanly divisible by 8, if so they are aligned. This counts for all partitions, not just the first one. Both starting sectors are, do the VM is aligned.
This wiki has been made possible by:
AD LDAP Authentication for Red Hat
Summary: How to configure AD authentication on Red Hat.
Date: Around 2014
Refactor: 29 March 2025: Checked links and formatting.
This manual continues where AD Identity Management for Unix stopped. Of course you'll also need Active Directory 2008 R2 Basic Installation and a default installed Red Hat server, I'm using a 5.5 Red Hat Enterprise Linux edition.
Now the default package you need for LDAP authentication (openldap and nss_ldap) are installed by default, but ldapsearch, which makes testing the setup very handy is not. You'll need the openldap-client package for that. You can install the package using yum by issuing the command yum install openldap-clients.
If you want to install from a DVD/CDROM you can use this this tutorial to add the media as a software repository.
Also note that you need a user with UNIX attributes set, as explained here.
Another remark is on the ldap configuration files, there are two and each is used for different purposes:
/etc/ldap.conf: # Used by pam to perform authentication. /etc/openldap/ldap.conf: # Used by the openldap tools and application to connect.