F-Response and Linux LVM, or how to handle non standard device entries

Nov 09, 2011

From time to time we get calls on Linux machines ( or really any non-Windows machines) that use non-standard device entries and the struggles the user is having getting F-Response to find and present those device entries. Much like anything technical it's rather easy once you understand what is going on, and while we do cover it in our manual we felt it would be good to get a brief post on the website here as well.

Let's start with a simple example.

We have a Linux machine here that is using a Logical Volume for the root device. Essentially Linux LVM("Logical Volume Manager") creates a thin software layer on top of the hard disks and partitions, creating an what basically amounts to a software RAID. There's more to LVM however, and if you are interested we recommend you take a few minutes to review the Wikipedia entry on Linux LVM.

This is actually more common than you would think, especially with Ubuntu and other desktop leaning Linux distributions. Now what's interesting here is that there are very few restrictions put on you (or in this case the installer) when creating a new Volume Group including how it is named. This makes things difficult for F-Response, as it is designed to look for traditional Linux devices (hda, hdb, sda, sdb, etc). However all is not lost, F-Response when run from the command line can be adjusted to test additional device entries by name.

Here's an example output from the mount command on a machine with a Logical Volume Group defined:

[root@testmachine ~]# mount

/dev/vg00/lv00 on / type ext3 (rw, noatime,errors=remount-ro)

Hmm, that clearly isn't a "well known" device mapping such as /dev/sda or /dev/sdb, so F-Response will need to be told about that device via the command line.

Let's assume you have followed one of the F-Response Mission Guide for manual deployment to a non-windows machine, such as this Mission Guide on F-Response Consultant edition and Linux.

Where we issue the following command "./f-response-ce-e-lin -c ./fresponse.ini" we need to add one more option, "-a /dev/vg00/lv00". Therefore the entire command would be:

[root@testmachine ~]# ./f-response-ce-e-lin -c ./fresponse.ini -a /dev/vg00/lv00

That command would instruct F-Response to check that device point and see if it can be loaded and presented, if so you'll see it listed in the output and be able to connect to it normally.

The "-a" option exists on all non-windows versions of F-Response and is a handy way to deal with exotic and non-standard device points. Also, don't forget, you can add multiple device entries if you separate them with a comma.

Thanks and enjoy! If you have any questions please don't hesitate to contact us, we are happy to help.

 

Warmest Regards,

M. Shannon, Principal

F-Response

November 9, 2011