Inquiry:How to recognize the assigned device for attached usb memory?

hadimotamedi · 12-21-2009, 05:33 AM

Dear All
I have attached usb memory to my Linux server and I want to add it to my /etc/fstab . Can you please let me know how can I recognize it from my"/dev/?" list ?
Thank you in advance

RichyAD · 12-21-2009, 05:56 AM

hadimotamedi, can you tell us which distro your linux server is running?

Normally usb drives are detected and mounted automatically. On Fedora usb drives are mounted under /media. For example: /media/usb/, /media/disk/, or /media/[drive name]

[EDIT]
usb devices can be located at: /dev/sda[1-9] to /dev/sdz[1-9], or even /dev/usb depending on the distro and hardware configuration.

hadimotamedi · 12-21-2009, 06:09 AM

Quote:

Originally Posted by RichyAD

hadimotamedi, can you tell us which distro your linux server is running?

Normally usb drives are detected and mounted automatically. On Fedora usb drives are mounted under /media. For example: /media/usb/, /media/disk/, or /media/[drive name]

[EDIT]
usb devices can be located at: /dev/sda[1-9] to /dev/sdz[1-9], or even /dev/usb depending on the distro and hardware configuration.

Thank you for your reply . I am using CentOS 5.2 . Can you please help me finding the assigned device ?

Davno · 12-21-2009, 06:16 AM

Hi,
I am not in front of a linux computer right now, so i can not be 100% certain about that, but i would look at the UUID number of your device and put that in my fstab.
Specially pratical if you need to identify one usb drive from another one for something like a backup script.
Might work !

linuxlover.chaitanya · 12-21-2009, 06:21 AM

You can check the device name from dmesg command.

hadimotamedi · 12-21-2009, 06:38 AM

Quote:

Originally Posted by linuxlover.chaitanya

You can check the device name from dmesg command.

How can read my device name "/dev/?" from dmesg output ?

linuxlover.chaitanya · 12-21-2009, 06:40 AM

Connect your device and then run dmesg command and look into the output of the command what it says.
Else do this and post the output here so that someone here can help you out.

evo2 · 12-21-2009, 06:43 AM

Run dmesg just after plugging in the device and look for lines near the end of the output containing "usb" and/or "/dev/sd"

Optionally, lsscsi is a useful command for this: but I don't if it is installed on your system.

Cheers,

Evo2.

linuxlover.chaitanya · 12-21-2009, 06:47 AM

Another way is to use it by uuid instead of name. uuid will not change even if the device is removed and re-plugged.
You can connect the device and then check for uuid in /dev/disk/by-uuid directory.

RichyAD · 12-21-2009, 06:57 AM

Additionally you can run "ll /dev/disk/by-label/". That'll give you a list of all attached labelled drives and their /dev/sd[].

hadimotamedi · 12-21-2009, 07:01 AM

Quote:

Originally Posted by evo2

Run dmesg just after plugging in the device and look for lines near the end of the output containing "usb" and/or "/dev/sd"

Optionally, lsscsi is a useful command for this: but I don't if it is installed on your system.

Cheers,

Evo2.

Can you please help me find it from the followings ?
[root@mss-0 ~]# dmesg |grep -i usb
usbcore: registered new driver usbfs
usbcore: registered new driver hub
usbcore: registered new driver hiddev
usbcore: registered new driver usbhid
drivers/usb/input/hid-core.c: v2.6:USB HID core driver
ehci_hcd 0000:00:0b.0: new USB bus registered, assigned bus number 1
ehci_hcd 0000:00:0b.0: USB 2.0 started, EHCI 1.00, driver 10 Dec 2004
usb usb1: configuration #1 chosen from 1 choice
hub 1-0:1.0: USB hub found
ohci_hcd: 2005 April 22 USB 1.1 'Open' Host Controller (OHCI) Driver (PCI)
ohci_hcd 0000:00:06.0: new USB bus registered, assigned bus number 2
usb usb2: configuration #1 chosen from 1 choice
hub 2-0:1.0: USB hub found
USB Universal Host Controller Interface driver v3.0
usbcore: registered new driver wcusb
Wildcard USB FXS Interface driver registered
INFO-xpp_usb: revision trunk-r6058
usbcore: registered new driver xpp_usb

linuxlover.chaitanya · 12-21-2009, 07:16 AM

Its not showing what the device is recognized as. Post the output without grep.
It should show something like this:

Code:

[28727.437375] sd 4:0:0:0: Attached scsi generic sg1 type 0
[28727.438886] sd 4:0:0:0: [sdb] 15679488 512-byte logical blocks: (8.02 GB/7.47 GiB)
[28727.439489] sd 4:0:0:0: [sdb] Write Protect is off
[28727.439493] sd 4:0:0:0: [sdb] Mode Sense: 23 00 00 00
[28727.439496] sd 4:0:0:0: [sdb] Assuming drive cache: write through
[28727.444246] sd 4:0:0:0: [sdb] Assuming drive cache: write through
[28727.444254]  sdb: sdb1
[28727.604384] sd 4:0:0:0: [sdb] Assuming drive cache: write through
[28727.604390] sd 4:0:0:0: [sdb] Attached SCSI removable disk

linuxlover.chaitanya · 12-21-2009, 07:18 AM

Also as I posted in earlier post, connect the device and check the entries in /dev/disk folder. You should have sub folder there for by-uuid, by-id and so on.
You could check with by-uuid or by-id for it. It would be much safer if you want to mount the usb device at boot. This would mount the device no matter if the name is changed.

evo2 · 12-21-2009, 09:06 PM

Quote:

Originally Posted by RichyAD

Additionally you can run "ll /dev/disk/by-label/". That'll give you a list of all attached labelled drives and their /dev/sd[].

"ll"? perhaps you have an alias of some sort?

Code:

type ll

Evo2.

evo2 · 12-21-2009, 09:08 PM

I wonder if you have the needed kernel moudles. Can you please post the output of

Code:

 lsmod | grep -E 'usb|scsi'

Evo2.