[BackupPC-users] OT: udev rule for persistent removable device naming

Hello!

My backup servers have a SATA removable drive tray installed in them. Its purpose is to be a target for BackupPC archvies (among other things) that allows the user to easily swap these. It is simply a physical tray: the system sees the drive inside of the tray exactly the same as any other internal SATA drive.

And that's part of my problem. With RHEL 6, I no longer have consistent (actually, persisitent) device naming. This system also uses a USB flash drive as its boot drive. It seems that there is a race condition during bootup. *Most* of the time, the USB device appears after the SATA drives, but not always. So, most times my tray shows up as /dev/sdd, but sometimes it shows up as /dev/sde. As you can imagine, this causes no end of problems with trying to create a script to safely partition and format the drive!

The (AFAIK) proper way to correct this is to create a udev rule to assign the tray device a persistent device name. However, because it's a removable tray, I can't use something like drive UUID or serial number to do this: the drive changes. I can't use SCSI path: it's the race condition that causes this one to change. And because sometimes the drive that I insert will be perfectly blank (a new drive), I can't use something like a drive label: it might not have one!

The only thing I *think* I can use is PCI bus address, and I don't know how reliable that might be. I don't want some *other* race condition to break things.

Does anyone else have any experience in this regard and might either be able to either point me in a better direction or give me an example of a udev rule that uses PCI address? I've Googled, but everything I can find uses things like drive ID or label. I can't find a single example with PCI bus address (DEVPATH).

Thank you for your help!

Timothy J. Massey


Out of the Box Solutions, Inc. Creative IT Solutions Made Simple! http://www.OutOfTheBoxSolutions.com tmassey AT obscorp DOT com		22108 Harper Ave. St. Clair Shores, MI 48080 Office: (800)750-4OBS (4627) Cell: (586)945-8796

------------------------------------------------------------------------------
Better than sec? Nothing is better than sec when it comes to
monitoring Big Data applications. Try Boundary one-second 
resolution app monitoring today. Free.
http://p.sf.net/sfu/Boundary-dev2dev

_______________________________________________
BackupPC-users mailing list
BackupPC-users AT lists.sourceforge DOT net
List:    https://lists.sourceforge.net/lists/listinfo/backuppc-users
Wiki:    http://backuppc.wiki.sourceforge.net
Project: http://backuppc.sourceforge.net/