From: Christopher M. Heffner (cheffner@xxxxxxxxxxxxxxxxxx)
Date: Tue Feb 20 2001 - 11:03:32 GMT-3
Hiya Folks -
You do not need to reformat the entire flash memory in order to move the
flash memory back to a single partition. You need to make sure that you
are currently booted from the first partition and then the second
partition will be read/write. Then you can erase the second partition
without effecting the first partition since it is still read-only. Once
the second partition is empty, then you can enter the command "no
partition flash 2" in global configuration mode. You will now have a
single read-only partition.
Second, you do not have to modify the configuration register to 0x101 in
order to upgrade a 2500 series. Leave the configuration register at
0x2102 and invoke the "copy tftp flash" command. Once you do this, the
router will start the Flash-Load Helper program which will automate the
copy process for you. You will need to be connect to the console in
order to see the whole process since the FLH program does the automatic
reboot "under the covers" to change the register settings for you. The
idea behind the FLH program is that folks will not have to know how to
modify the configuration register. This process does not work for the
1600 Run-from-Flash routers since they use PCMCIA cards. Changing the
register manually will still work but it takes longer and could lead to
mistakes.
BTW - partitioning can also be done on Run-from-Ram routers such as
1700, 2600, 3600, 4500, 4700, etc.
Trivia question - why would you want to partition read/write flash in a
Run-from-Ram router? What is the benefit ??
All of this is taught as part of the Cisco IMCR class.
Christopher M. Heffner
IMCR Course Director
Certified Cisco Systems Instructor
CCSI, CCNA, CCDA, CCIE Candidate
MCT, MCSE, MCNI, MCNE, CLI, CLP, ASE, CTT, A+
cheffner@certified-labs.net
March 7-8 (Halifax)
-----Original Message-----
From: Derek Small [mailto:dwsmall@fatkid.com]
Sent: Monday, February 19, 2001 11:04 PM
To: Scott Schneidewind
Cc: ccielab@groupstudy.com
Subject: Re: Changing flash from "Read only"
Scott,
The 2500 series (and earlier 1600 series) routers as called "run from
flash"
routers. That is, they execute IOS instructions in flash memory, not
RAM
like most conventional computing devices. Since you are executing code
in
flash memory you cannot modify it, or you will, in effect, be modifying
your
operational RAM, sometimes called an abend or general protection fault.
2500 routers give you the option of partitioning the flash memory into
two
segments, so you can modify one, and leave the other undisturbed. To
return
the router to a single partition you have to format the entire flash.
To do
that, you have to boot the router to <boot> mode. 2500 routers do not
have
boot flash, like some of the larger routers, but they do have a boot ROM
which holds a minimal IOS image, to get basic IP functionality working,
just
like a boot flash image. Set the config register to 0x101 and reboot
the
router to get it to boot to a router<boot> prompt. The flash memory
will
then be writable. You can then format your entire flash as a single
partition and then tftp a new IOS to the router. Reset your config
register
when you are done.
Derek Small
CCIE # 5832, CVoice, Nortel NCSE
dwsmall@fatkid.com
----- Original Message -----
From: "Scott Schneidewind" <schneids@ispchannel.com>
To: <ccielab@groupstudy.com>
Sent: Monday, February 19, 2001 4:18 PM
Subject: Changing flash from "Read only"
> Hello all.
> I have some 2501 routers which each have two 8Mb sticks of flash ram
in
> them.
>
>
> "Show Flash" lets me know that one is read/write and the other is read
only.
> How can I change the read only partition...so it can be erased and
combined
> with the other one.
>
> -Scott
>
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