Boot order when using multiple IOS Images

[jeff.bankston]

Okay, simple question:

I have slot0 with two images, disk0 with one image, both flashes in the same router, a 7204-VXR. If the boot system command is not specified pointing to a particular image, which image will be used to start the router? What is the deciding factor in the boot order?

I can't find a single thing on CCO relating to this ordering process.

Thanks, Jeff

[Craig Norborg]

It depends a bit on the router. Usually whatever is the first boot device (bootflash?) and whatever is the first image on that device is loaded first.

However, the easy way to set the boot order is to do a multiple "boot system flash" commands. Whatever order they are in your configuration is the order they're tried in. Be sure to put them into the config in the order you wanted them to be, there is not way to reorder them beyond doing a "no boot ..." on each line that is out of order and putting it back in the right order...

ex:

boot system flash disk0:c7200-is-mz.123-1a.bin

boot system flash disk0:c7200-is-mz.123-5b.bin

would first try booting the 12.3(1a), then the 12.3(5b) if the first failed.

to find out the order they're in, its easiest to do a:

sh run | i boot

Hope this helps...

[jeff.bankston]

'preciate the response, but no it doesn't help.

I know all about the boot commands, but just have never really tried to nail down an unordered boot process before.

Thanks, Jeff

[MillWill]

The boot order is selected by which order it appears in the flash: this can be confused looking at the Dir flash: command as it may be the first there but not the first in flash:

Example: Below shows the order the IOS appears when using dir flash: from that output you would assume if the IOS is not set with Boot system flash: it would boot c1100-universalk9.17.06.05.SPA.bin first but this would be wrong as the show flash: output below shows /bootflash/c1100-universalk9.17.04.01a.SPA.bin is the first IOS listed in flash.

21 -rw- 706577188 Sep 28 2023 13:01:36 +00:00 c1100-universalk9.17.06.05.SPA.bin
20 drwx 4096 Jun 23 2022 14:30:38 +00:00 lost+found
17 -rw- 462378256 Jul 2 2021 10:54:33 +00:00 c1100-universalk9_ias.16.09.04.SPA.bin
19 -rw- 650526876 Jun 15 2021 12:42:58 +00:00 c1100-universalk9.17.04.01a.SPA.bin

ouseRouter#sh flash: | begin /bootflash/c11
679 650526876 Jun 15 2021 12:42:58.0000000000 +00:00 /bootflash/c1100-universalk9.17.04.01a.SPA.bin
680 462378256 Jul 02 2021 10:54:33.0000000000 +00:00 /bootflash/c1100-universalk9_ias.16.09.04.SPA.bin
681 776 Apr 15 2025 19:50:00.0000000000 +00:00 /bootflash/vlan.dat
682 4096 Jun 23 2022 14:30:38.0000000000 +00:00 /bootflash/lost+found
683 706577188 Sep 28 2023 13:01:36.0000000000 +00:00 /bootflash/c1100-universalk9.17.06.05.SPA.bin

resulting in the IOS loaded was /bootflash/c1100-universalk9.17.04.01a.SPA.bin

Cisco IOS XE Software, Version 17.04.01a
Cisco IOS Software [Bengaluru], ISR Software (ARMV8EL_LINUX_IOSD-UNIVERSALK9-M), Version 17.4.1a, RELEASE SOFTWARE (fc4)