How to detect new hard disk
But what if you are in no position to reboot the Guest Linux OS?
Solution
In the below path you can find a list of host symlinks pointing to the iscsi device configured on your Linux box
# ls -l /sys/class/scsi_host/ total 0 lrwxrwxrwx 1 root root 0 Jun 14 05:08 host0 -> ../../devices/pci0000:00/0000:00:07.1/host0/scsi_host/host0 lrwxrwxrwx 1 root root 0 Jun 14 05:08 host1 -> ../../devices/pci0000:00/0000:00:07.1/host1/scsi_host/host1 lrwxrwxrwx 1 root root 0 Jun 14 05:08 host10 -> ../../devices/pci0000:00/0000:00:11.0/0000:02:05.0/host10/scsi_host/host10 lrwxrwxrwx 1 root root 0 Jun 14 05:08 host2 -> ../../devices/pci0000:00/0000:00:10.0/host2/scsi_host/host2 lrwxrwxrwx 1 root root 0 Jun 14 05:08 host3 -> ../../devices/pci0000:00/0000:00:11.0/0000:02:05.0/host3/scsi_host/host3 lrwxrwxrwx 1 root root 0 Jun 14 05:08 host4 -> ../../devices/pci0000:00/0000:00:11.0/0000:02:05.0/host4/scsi_host/host4 lrwxrwxrwx 1 root root 0 Jun 14 05:08 host5 -> ../../devices/pci0000:00/0000:00:11.0/0000:02:05.0/host5/scsi_host/host5 lrwxrwxrwx 1 root root 0 Jun 14 05:08 host6 -> ../../devices/pci0000:00/0000:00:11.0/0000:02:05.0/host6/scsi_host/host6 lrwxrwxrwx 1 root root 0 Jun 14 05:08 host7 -> ../../devices/pci0000:00/0000:00:11.0/0000:02:05.0/host7/scsi_host/host7 lrwxrwxrwx 1 root root 0 Jun 14 05:08 host8 -> ../../devices/pci0000:00/0000:00:11.0/0000:02:05.0/host8/scsi_host/host8 lrwxrwxrwx 1 root root 0 Jun 14 05:08 host9 -> ../../devices/pci0000:00/0000:00:11.0/0000:02:05.0/host9/scsi_host/host9
But to detect a new hard drive attached you need to first get your host bus number used which you can get by using below command
# grep mpt /sys/class/scsi_host/host?/proc_name
You should get a output like below
/sys/class/scsi_host/host2/proc_name:mptspi
So as you see your host2 is the relevant fields where you need to reset the storage buffer values. Run the below command
# echo "- - -" > /sys/class/scsi_host/host2/scan
Here "- - -" defines the three values stored inside host*/scan i.e. channel number, SCSI target ID, and LUN values. We are simply replacing the values with wild cards so that it can detect new changes attached to the Linux box. This procedure will add LUNs, but not remove them.
Once done verify if you can see the new hard drive which in my case worked very fine as I see below
# fdisk -l Disk /dev/sdb: 3221 MB, 3221225472 bytes 255 heads, 63 sectors/track, 391 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000
Let me know your success and failures.
Hello Prasad,
Quick tip:
A better way to identify new disks is using the rescan-scsi-bus.sh script.
You can install it with by 'yum install sg3_utils'.
Some options you'll want to use are: -c or -cr.
By the way, your 'Configure Red Hat Cluster using VMware, Quorum Disk, GFS2, Openfiler' is really good. Congrats and keep the good tutorials.
great, it was what i was looking for
work on sles 11 sp3. ( over vmware)
in messages log you can see the adition.
We can also check the newly added disks using dmesg command
Thank you..
Hi,
This article is very nice, it helped me a lot.
Keep posting this kind useful information.
Thanks a lot
Thanks
what is kernel patching
how to upgrade kerner patching
send me answer in brief please
Thanks for sharing nice info.
worked like a charm!
Great job…. keep posting this kind useful information.
Thanks
Great job…. keep posting this kind useful information.
I had a permission denied error until I did the following on the echo line:
sudo bash –c ‘echo “- – -“ > /sys/class/scsi_host/host2/scan’
Then all was right with the world. Thanks for the very useful article 🙂
Fantastic article :
Could you please suggest any books for mastering in Linux
This article is very help full for me thanks
It worked. Thanks