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 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.
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.
Red Hat ACL or Extended Permissions
Summary: How to work with ACLs on Red Hat.
Date: Around 2014
Refactor: 29 March 2025: Checked links and formatting.
The filesystems ext2/3/4 also support more complex file permissions called ACLs. I will not cover that deeply, just enough to get you going.
Red Hat Enterprise Linux 6.5 Management Server
Summary: How to configure a Red Hat Management Server. This means a complete installation as well as setting up the kickstart installation server.
Date: Around 2014
Refactor: 29 March 2025: Checked links and formatting.
This article is the first, or actually the second in a series of installing Red Hat Enterprise Linux at a company. Right now I work in a Windows based environment, but unfortunately for my colleagues not every application runs on Windows. Especially the ones that are designed to do a lot of math based tasks, in this case risk calculations. In previous versions, these applications were installed on physical hardware with Solaris and a little bit of an ancient Red Hat edition. However, new releases, new chances and I had the chance to recreate everything from scratch, supported and well, on virtualized hardware. So I've already done my homework and got together a best practices for Red Hat on VMware, created a design which included a management server, a NFS server and all required application and database server. This article is about the management server. The idea is that this server will be the central point in the linux environment and will be used as an installation server, as well as the OS as software and patches, the Mercurial versioning master repository and a few more smaller functions. More then that, this is the first server, so it will be installed from scratch, and this is the report.
At the end you can read how to use this management server to install other servers, which is then followed by a Post Install follow-up.
Enjoy.
Update: I also came up with a requirement to mount Windows shares to some of my Linux boxes, I finally opted for Windows NFS and documented that here.