Changing Permissions on Hard Drive Device Files

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j1974
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Joined: 2009/10/28 13:43:35

Changing Permissions on Hard Drive Device Files

Post by j1974 » 2009/10/28 14:05:23

Is there any potential harm in adding read permissions to a device driver file in Centos while the drive is mounted?

This is what the device files look like on this machine:

brw------- 1 root root 104, 0 Oct 7 23:03 /dev/cciss/c0d0
brw------- 1 root root 104, 1 Oct 7 23:03 /dev/cciss/c0d0p1
brw------- 1 root root 104, 10 Oct 7 23:03 /dev/cciss/c0d0p10
brw------- 1 root root 104, 2 Oct 7 23:03 /dev/cciss/c0d0p2
brw------- 1 root root 104, 3 Oct 7 23:03 /dev/cciss/c0d0p3
brw------- 1 root root 104, 4 Oct 7 23:03 /dev/cciss/c0d0p4
brw------- 1 root root 104, 5 Oct 7 23:03 /dev/cciss/c0d0p5
brw------- 1 root root 104, 6 Oct 7 23:03 /dev/cciss/c0d0p6
brw------- 1 root root 104, 7 Oct 7 23:03 /dev/cciss/c0d0p7
brw------- 1 root root 104, 8 Oct 7 23:03 /dev/cciss/c0d0p8
brw------- 1 root root 104, 9 Oct 7 23:03 /dev/cciss/c0d0p9


Our backup software needs group read on these files to access them. Can I "chmod g+r" these device files I've listed without unmounting or doing anything special, and without causing any harm? It's on a production server, so we'd like to do it without doing a reboot, if possible.

pschaff
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Changing Permissions on Hard Drive Device Files

Post by pschaff » 2009/10/28 14:18:18

Looks like you would need to change the group as well as the permissions. Don't see why either would cause a problem; however, is the backup software working on the devices or the filesystems? If the raw devices then it probably needs to run as root. If the filesystems, then there's no need to change the ownership on the device files.

j1974
Posts: 5
Joined: 2009/10/28 13:43:35

Re: Changing Permissions on Hard Drive Device Files

Post by j1974 » 2009/10/28 14:41:06

Yes we're using amanda so it is operating directly on the block device. Thanks for the input.

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