Compiling a new RHEL-4 kernel

[Simon]

On Dec 20, 2005, at 6:25 AM, Tom Callahan wrote:

> First off, this will void your support contract. But to get the kernel
> sources, read the RHEL4 release notes available on redhat's site.
>
> As far as your tape changer issue, verify that sg5 is indeed your
> changer and not an individual tape device. Once you have verified  
> that,
> create a symlink /dev/changer -> /dev/sg5
>
> `mtx status` should then show you stats about your changer.

The problem is that both robot and changer are set to /dev/sg5 - the  
device uses different LUNs to distinguish and RHEL is set up to not  
scan for different LUNs per SCSI device by default :-(

I get an ok response from the command:

	mtx -f /dev/sg5 inquiry

... but

	mtx -f /dev/sg5 status

... fails miserably.

> NOTE: /dev/st0 will rewind the tape after each write, /dev/nst0 will
> not, I recommend if using a tape for backup, that you use /dev/ 
> nst0, and
> then manually issue a rewind at the end of the backup functions. This
> prevents you from inadvertantly overwriting previously backup up data.

Yeah, I know - the tape is ~400GB (an Ultrium-3), so the backup  
(~250GB) fits on fine, and there are 8 tapes in the device. At the  
moment, the service people are using the front-panel controls to  
manually switch tapes on a day-by-day basis. This gives us a rolling  
backup for a week. When I get the tape robot working properly, I'll  
start writing scripts to do both full and incremental backups and  
load/unload tapes on-demand...

A new (clone) server will appear in the next few days, so I'm going  
to wait until that arrives before fiddling with kernel parameters  
(I'd rather test hardware on the machine that *isn't* serving a few  
hundred websites [grin])

Thanks for the help though :-)

ATB,
	Simon