Re: some basic Unix for an Oracle startup DBA

Ralph apparently said,on my timestamp of 6/03/2005 4:28 PM:

>
> I dont know the answers to what I had posted. For example, I learnt
> that in c0t0d2s4, t is target device, but I do not know what a target
> device is. I have a few books on Unix and Linux including Bill Calkins'
> Inside Solaris 9 and Evi's Linux Admin book. I cant find that in them.

http://www.adminschoice.com/docs/vxvm.htm

The traditional convention is for the "cn" to be the controller number, the "tn" is the (SCSI id) target number, the "dn" is the disk group number and the "sn" is the slice number in a multi-sliced (multi-partitioned) disk.
So, your c0t0d2s4 means "controller 0", "SCSI-ID 0", "disk group 2", "slice 4".
Sun and some others still use this convention. AIX, Linux and a few others simply use the "major/minor" device number in a mknod with a simpler device name convention.

All it is is a method for telling you which portion of which logical disk you're dealing with.

> I am also trying to find out about some shared memory segment parameter
> details. Oracle says set SHMMAX, SHMMIN, etc. to certain values, but
> doesnt explain what they are clearly. (I have to admit I didnt read all
> Oracle manuals).

Shared memory in Unix is governed by a number of parameters that define its maximum size, the number of segments, the size of each segment, etc. These parameters simply define to Unix what to reserve for in its virtual memory page management tables.

In some older versions of Unix, shared memory is set too low by default. Oracle relies a lot on shared memory, so you need to change the defaults. More modern versions simply don't have this problem. There is an administrator's manual for Unix in the Oracle manuals that explains the relevance or not of these parameters for each Unix/Linux port, and how to change them in each case.

> CC: What you are saying is pretty much what I hear from others - Go
> Linux if starting new. But, I guess my questions on Linux still remain
> the same. I will have to learn about file systems and anything and
> everything to be a good Oracle DBA.

Go here for Linux:
http://web.whittier.edu/jlutgen/rute/rute.html it's a good read, take your time.

I still recommend you go through Kernighan's book: it will teach you the basics of running and administering Unix and what all those mysterious directories/files are for. Then it will be a lot easier to understand other Unix ports and to see how much simpler Linux can be.

HTH
Cheers
Nuno Souto
in sunny Sydney, Australia
wizofoz2k_at_yahoo.com.au.nospam Received on Sun Mar 06 2005 - 04:38:58 CST