OS level and Description

IBM first releases AIX base levels for a particular version such as AIX 5.3, 6.1 or 7.1 , then IBM regularly releases updates related with various enhancement , bugs and security vulnerabilities. These are packed together as Technology Levels (TLs) or Service Packs (SPs).The oslevel command reports the base level and “-r” flag includes TL levels information and the “-s” flag includes service pack information as shown below

webmanual01:/> oslevel
6.1.0.0
webmanual01:/> oslevel -r
6100-06
webmanual01:/> oslevel -s
6100-06-05-1115

Format of the oslevel -s output is : Base Level-Technology Level-Service Pack:YYMM
Now let me explain the format with oslevel -s output 6100-06-05-1115

1) The first four numbers show the AIX base level. In our example, it’s 6100, which means we are running AIX 6.1. 2) Next is the Technology Level (TL),In our example,it’s 06 ,which means we have TL 6 installed 3) Followed by the number of the Service Pack (SP). In our example,it’s 05 which means we have SP 5 installed 4) The last four digits show the release date of the Service Pack using the format YYWW (YY for the year, then WW for the week of the year). In our example,it’s 1115 which means Service Pack was released in week 15 of 2011

Hence in our example “oslevel -s” command reports 6100-06-05-1115, so our system have AIX 6.1, running TL 6, with SP 5. The 1115 tells Service Pack was released in week 15 of 2011
Technology Level vs Service Pack(TL vs SP)
A TL includes new functions and features, whereas a SP contains fixes for bugs/problems that are critical and need to fix those bugs/problems quickly even we can not wait until the next TL. Service Packs are limited to minimal corrections and a new SP does not add any new functionality or feature.

For example, AIX 7.1 has features such as volume groups exclusively for solid state disks which IBM has included in AIX 6.1 with TL 6. So if we were running AIX 6.1 with a older TL then we need to update to TL 6 to take advantage of this features. H ere I have taken a example of one but in a newly released TL includes lots of other features and functionalists.

There are also interim fixes which we call e-fix,if we can’t wait for the next SP to be released then we can install e-fix. But personally my experience do not prefer those.

 * Source Article from : Internet