At any rate, congratulations on running the unarguably superior Linux distribution. Here’s some things you should know.

RHEL Version and Alternatives

RHEL5 vs RHEL6

There’s only one viable reason to go with RHEL5 at this point: You’re deploying a new server to an existing cluster of RHEL5 servers.

Other than that, you should now be using RHEL6. It’s past the initial release phase; it’s been out long enough to have proven itself stable; and by virtue of being a later version, it’ll be supported longer than RHEL5.

Distribution Alternatives

My advice? Don’t. But if you have to?

For many years, CentOS has been the “free” compatible alternative of choice for RHEL. There’s been concern over update frequency/lag time behind RHEL of late. Some have been looking at Scientific Linux as a result, but you can expect a visit from John Titor if you go down that route.

Where My Packages At?

Third party repositories are a necessity with RHEL. The fact is, developers are all whiny about new features and sharp pointy things they can injure themselves and your infrastructure with. Best to just give them what they want – and with RHEL, you can, while maintaining your sanity.

MySQL

If you’re running MySQL, you have no excuse whatsoever to not be running Percona. Percona is the Bugatti Veyron of MySQL, whereas every distributions’ default MySQL packages are nothing more than a bunch of Honda Accords. Percona Server is a drop-in replacement; your data is unaffected and you can revert to conventional MySQL at any time with no risk. Percona offers consulting and on-demand support; they’ve got enterprise paranoia, err, needs, covered. Percona currently offers 5.1 and 5.5 variants; there’s little reason not to go with 5.5 these days. I think they have Ubuntu packages now too, for you crazy kids who are into kinky stuff.

PHP

If you’re running PHP, Zend CE is the answer. Ever wonder how to get PHP 5.2 on a RHEL5 system without using packages that haven’t been maintained in a year? Or perhaps you just want PHP to actually be, you know, fast. Install Zend CE and you’ll have a well-documented, well-supported, optimized-to-hell-and-back PHP stack, from Zend. From freaking Zend, people. Zend CE currently offers PHP 5.2 and 5.3 flavors.

Ruby

Ruby’s the new Perl (and then some); and like the good old days of Perl, there’s an overinflated version hell problem. Unlike Perl, Ruby isn’t old enough to have stabilized to the point where you can run what your distribution provides and be happy. rbel.frameos.org may be the answer here – if and only if you’re working with Ruby 1.8. If you are, you can look forward to a repository filled with 1.8 goodness as well as things like Chef and Node.

If you want to run with 1.9? Good luck with that. The only viable option I’ve found so far is RVM, which lends itself to operational nightmares. (“Let’s make thirty two copies of this out of date gem with a security vulnerability! That’s easy to update, right?”)

I’m starting to suspect Ruby is nothing more than an insidious exit plan for exhausted sysadmins. Learn Rails, become overpaid; welpguesssomeoneelseneedstoberesponsibleforuptimeImtoobusydeveloping. Genius.

Everything Else

EPEL is your answer for all those miscellaneous packages, such as git and whatnot.

Linux

36    37   | 38    39   | 40    41   | 42    43   | 44    45   | 46    47
sdab  sdaf | sdt   sdx  | sdar  sdav | sdaj  sdan | sdl   sdp  | sdd   sdh
-----------+------------+------------+------------+------------+-----------
24    25   | 26    27   | 28    29   | 30    31   | 32    33   | 34    35
sdaa  sdae | sds   sdw  | sdaq  sdau | sdai  sdam | sdk   sdo  | sdc   sdg
-----------+------------+------------+------------+------------+-----------
12    13   | 14    15   | 16    17   | 18    19   | 20    21   | 22    23
sdz   sdad | sdr   sdv  | sdap  sdat | sdah  sdal | sdj   sdn  | sdb   sdf
-----------+------------+------------+------------+------------+-----------
00    01   | 02    03   | 04    05   | 06    07   | 08    09   | 10    11
sdy   sdac | sdq   sdu  | sdao  sdas | sdag  sdak | sdi   sdm  | sda   sde
 BOOT DEV

Solaris

36    37   | 38    39   | 40    41   | 42    43   | 44    45   | 46    47
c3t3  c3t7 | c2t3  c2t7 | c5t3  c5t7 | c4t3  c4t7 | c1t3  c1t7 | c0t3  c0t7
-----------+------------+------------+------------+------------+-----------
24    25   | 26    27   | 28    29   | 30    31   | 32    33   | 34    35
c3t2  c3t6 | c2t2  c2t6 | c5t2  c5t6 | c4t2  c4t6 | c1t2  c1t6 | c0t2  c0t6
-----------+------------+------------+------------+------------+-----------
12    13   | 14    15   | 16    17   | 18    19   | 20    21   | 22    23
c3t1  c3t5 | c2t1  c2t5 | c5t1  c5t5 | c4t1  c4t5 | c1t1  c1t5 | c0t1  c0t5
-----------+------------+------------+------------+------------+-----------
00    01   | 02    03   | 04    05   | 06    07   | 08    09   | 10    11
c3t0  c3t4 | c2t0  c2t4 | c5t0  c5t4 | c4t0  c4t4 | c1t0  c1t4 | c0t0  c0t4
 BOOT DEV

OpenSolaris

36    37    | 38    39    | 40    41    | 42    43    | 44    45   | 46    47
c11t3 c11t7 | c10t3 c10t7 | c13t3 c13t7 | c12t3 c12t7 | c8t3  c8t7 | c7t3  c7t7
------------+-------------+-------------+-------------+------------+-----------
24    25    | 26    27    | 28    29    | 30    31    | 32    33   | 34    35
c11t2 c11t6 | c10t2 c10t6 | c13t2 c13t6 | c12t2 c12t6 | c8t2  c8t6 | c7t2  c7t6
------------+-------------+-------------+-------------+------------+-----------
12    13    | 14    15    | 16    17    | 18    19    | 20    21   | 22    23
c11t1 c11t5 | c10t1 c10t5 | c13t1 c13t5 | c12t1 c12t5 | c8t1  c8t5 | c7t1  c7t5
------------+-------------+-------------+-------------+------------+-----------
00    01    | 02    03    | 04    05    | 06    07    | 08    09   | 10    11
c11t0 c11t4 | c10t0 c10t4 | c13t0 c13t4 | c12t0 c12t4 | c8t0  c8t4 | c7t0  c7t4
 BOOT DEV

Nexenta

36    37   | 38    39   | 40    41   | 42    43   | 44    45   | 46    47
c4t3  c4t7 | c3t3  c3t7 | c6t3  c6t7 | c5t3  c5t7 | c1t3  c1t7 | c0t3  c0t7
-----------+------------+------------+------------+------------+-----------
24    25   | 26    27   | 28    29   | 30    31   | 32    33   | 34    35
c4t2  c4t6 | c3t2  c3t6 | c6t2  c6t6 | c5t2  c5t6 | c1t2  c1t6 | c0t2  c0t6
-----------+------------+------------+------------+------------+-----------
12    13   | 14    15   | 16    17   | 18    19   | 20    21   | 22    23
c4t1  c4t5 | c3t1  c3t5 | c6t1  c6t5 | c5t1  c5t5 | c1t1  c1t5 | c0t1  c0t5
-----------+------------+------------+------------+------------+-----------
00    01   | 02    03   | 04    05   | 06    07   | 08    09   | 10    11
c4t0  c4t4 | c3t0  c3t4 | c6t0  c6t4 | c5t0  c5t4 | c1t0  c1t4 | c0t0  c0t4
  BOOT DEV

…s’alot of disks.

Set new UUID on XFS Partition, RHEL/CentOS:

xfs admin -U generate /dev/sdb1

Set new UUID on XFS Partition, SLES/OpenSUSE:

xfs_admin -U generate /dev/sdb1

Set new UUID on ext3 Partition and Display New UUID (RHEL/CentOS, SLES/OpenSUSE):

tune2fs /dev/sdb1 -U random
dumpe2fs -h /dev/sdb1 | grep UUID

Fun, no?