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Using compact flash disk

wilson_1234_2
Level 3
Level 3

I have a new 7206 router that I will put in place soon.

In the meantime, I would like to take the opportunity to experiment with using the flash disk.

I have looked at the document on Cisco's site, but it is very basic.

I have a couple of questions:

1. My understanding is the boot image can be on onboard flash or the compact flash and by default the router will check on board flash first, then the compact flash, is this correct?

2. What are the most common usage for the flash disk?

3. Below is from another 7206 in production:

7206VXR#sh bootvar

BOOT variable = disk0:c7200-jk9o3s-mz.123-14.T7.bin,12;

CONFIG_FILE variable does not exist

BOOTLDR variable does not exist

Configuration register is 0x2102

7206VXR#sh flash

Open device slot0 failed (No such device)

It looks like there is no onboard flash on this router and everything is located on disk0:

7206VXR#dir

Directory of disk0:/

1 -rw- 1807 Jan 20 2005 21:20:58 -05:00 home.shtml

2 -rw- 26792036 Apr 03 2006 13:32:22 -04:00 c7200-jk9o3s-mz.123-14.T7.

bin

3 -rw- 93095 Jan 20 2005 21:20:58 -05:00 attack-drop.sdf

4 -rw- 270848 Jan 20 2005 21:21:00 -05:00 home.tar

5 -rw- 1187840 Jan 20 2005 21:21:02 -05:00 ips.tar

6 -rw- 3885056 Jan 20 2005 21:21:10 -05:00 sdm.tar

7 -rw- 1463 Jan 20 2005 21:07:42 -05:00 home.html

4. Did anything have to be done to this router for the router to boot (other than modify bootvar) or is this default behavior?

5. What is the upgrade procedure if I need to put an upgrade image larger than what this disk can hold?

40 Replies 40

Richard

I use it for testing purposes and also in case i make a typo and then it just fails through to the next one.

Yes the switch will always try and boot the first one in the running-config if you have specified it.

Would have to run quick test with 6500. Certainly with no bootvar it would load image in sup-bootflash but not sure it there wasn't one there it would move onto disk0:

Perhaps someone else knows for sure ?

Jon

Besides testing, you can use multiple different bootvars to help support quick device recovery. Especially handy on devices that contains multiple flash devices, especially removables.

e.g.

boot system flash disk1:intended_image.bin

boot system flash disk1:

boot system flash disk0:

If the first boot var isn't found, it continues down the list. Assume there's a major problem with disk1:intended_image.bin, We can very quickly boot into an image on disk0 just by pulling the disk1 device or swap disk1 media and reload. Neither requires changing the config.

Sometimes very handy when the device is remote and there's no local support staff and you've lost connectivity to the box. You can usually talk an admin person through pulling a compact flash module (or swapping it with another) and power cycling the system.

Jon,

Sorry for this, but

Are you saying the you usually have more than one image loaded and as in the upgrade example?

You put both entries in the boot var, for instance in my case,

I load the new image onto compact flash and that is the first entry in bootvar, I leave the other image in the sup flash, if I have a typo, the switch will boot to the old image?

Also on the location of the images, does it matter that if I leave it in the compact flash?

I do not understand why it has not been used, or is it possible to move the image from one place to another (compact flash to sup flash) during operation?

Also, I see there is an image in bootflash (an earlier image) and one in sup bootflash, there are three locations to load an image?

Richard

No need to apologize.

Some images will not fit on the bootflash or the sup-bootflash and so you have no choice but to boot off a compact flash card.

In addition it's important to remember that if the only image you have is on compact disk then someone can simply remove the disk. Next time the switch reloads it won't have an inmage to boot.

If i had the space i would try and ensure the image i wanted to use would be on internal flash.

You can copy the image around between compact flash and sup flash, again subject to space considerations, but the switch will not move it itself.

Jon

Excellent points everyone.

So, what I could do since the switch is booting from sup flash:

Load the new image onto cpmpact flash, while adjusting the bootvar to boot to both with the new image being the first to try (from compact flash).

Once I am sure the new image is a good one, I could erase the old image off of sup flash and copy the new upgrade image onto sup flash in a second location.

Then adjust the boot var accordingly.

This way, if the flash gets removed or corrupted in some way, upon reboot, I am booting to my upgraded image from supflash also.

Does that sound like a working plan?

By the way, I appreciate all of the assistance. I could never read the documents and get as good an understanding as I do when you guys help with the real works conditions.

It is greatly appreciated.

Richard

Sounds like a very sound plan of action.

As for assistance, without presuming to speak for everyone, i think we all enjoy helping others out and thanks for all the ratings which shows your appreciation.

Jon

You bet Jon,

It is greatly appreciated, and a good source for others to learn from as well.

One last hint, not uncommon to run out of space on flash with newer IOSs or larger feature set versions. If the device supports external flash, usually easy to obtain a larger one. But if internal flash isn't large enough, how might it be used?

I've often loaded an older or reduced feature set IOS that fits on the internal flash and run the current IOS from external flash. This often then allows a "backup" IOS if something goes wrong with the current external version. (Often much nicer to deal with than ROMMON.)

Richard

Sorry missed this bit

"This also means that I could copy the new image at any time I want?"

Yes you can copy it onto disk0: anytime and it will not affect the normal operation of the switch.

Jon

Jon,

You had some queries earlier in this thread. See my response(s) inline. May be this would address Richard's concern as well with regard to the upgrade process.

""Would have to run quick test with 6500. Certainly with no bootvar it would load image in sup-bootflash but not sure it there wasn't one there it would move onto disk0:""

No it won't look for an image on disk0 if no valid image couldn't be found in the sup-bootflash. Anytime you want the switch to boot from an external flash card you certainly need the boot system commands configured.

""I use it for testing purposes and also in case i make a typo and then it just fails through to the next one.

Yes the switch will always try and boot the first one in the running-config if you have specified it.""

I believe it will try 3 or 4 times to boot from the 1st image in the boot statement and if it fails it would attempt to boot from the next image in the list (top-down).

HTH

Sundar

Sundar

Thanks for confirming that, couldn't remember how it worked if there was only an IOS on compact flash but no boot variable.

Jon

Sundar,

I have some questions (config oriented)regarding the installation of the 7206 if you are up for it.

In a new post.

Certainly. Go for it.

Thanks,

I will post that one tomorrow.

One thing I forgot to ask on the flash:

Suppose something goes wrong and I boot to rommon,

I have two images, but the switch only tries the first one and then boots to rommon,

Can I remove the first line in the start config to boot to the second image while in rommon?

I hope nothing goes wrong for you with this upgrade.

If it does follow the rommon recovery procedures listed in this document.

http://www.cisco.com/en/US/products/hw/switches/ps700/products_tech_note09186a008015bfa1.shtml

As you can see in this document you would use the boot bootflash:<2nd_image_name> command in the rommon mode to make the switch boot from that image.

HTH

Sundar

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