Archive for the ‘VMware’ Category
How to add a SCSI disk ‘on the fly’ with RedHat Linux
Today I provisioned a new RedHat VMware ESX 2.5 guest at the request of the web hosting department. They requested a standard build which consists of a 9GB disk for the Operating System. They also requested an additional 80GB disk for data. The standard build consists of (only) OS on local disk, with application data on the SAN. This is build is platform agnostic and thus applies to both physical servers and VMware guests.
The normal procedure is to attach all of the storage while the VMware guest is powered off, but today I used this as an opportunity to get RedHat to add the 80GB SCSI data disk on the fly.
I powered up the VM and installed the OS according to the build specification. I then attached the 80GB SCSI data disk while the VMware guest was running. VMware reported this operation a success. The next task was to get Red Hat to “re-scan” the SCSI bus and detect the new disk.
The command: echo “- – -” > /sys/class/scsi_host/host0/scan worked without error. I then ran “fdisk -l” and immediately I was presented with a new /dev/sdb disk ready to be configured.
NOTE: The Red Hat Knowledge Base (RHKB) states that the recommend way to add new SCSI disk under Red Hat Linux is to switch off the server before attaching the new disk. The above procedure was tested on RedHat EL ES 4.6 (Nahant)
