In web server administration, there are instances where you might need to increase the storage capacity of your Linux RHEL 6 server. This could be due to a variety of reasons, such as the need for more space to store data or to improve the performance of your server. However, rebooting the server to add a new hard disk is not always feasible, especially in a production environment. <\/p>\n
This tutorial will guide you on how to add a new hard disk to your server without having to reboot it. This process is particularly applicable if your server is running on a VMware ESXi machine. The steps outlined here have been tested on Red Hat Enterprise Linux 6 (RHEL 6), but they may also work on RHEL 5 and CentOS 5.<\/p>\n
The first step in this process is to add a new disk to the VM Guest through VMware vCenter Server\/VMware vSphere. In this tutorial, we will be adding a 12 GB space to the second hard disk space, which is on the raw device \/dev\/sdb.<\/p>\n
Once you’ve added the new disk, the next step is to find the scsi_host value. This can be done using the following command:<\/p>\n
\r\n[root@rhel6 ~]# ls \/sys\/class\/scsi_host\r\nhost0 host1 host2\r\n<\/pre>\nIn this RHEL 6 server, there are three scsi_host values: host0, host1, and host2.<\/p>\n
The third step is to rescan the SCSI Bus to add the SCSI Device without rebooting the VM. This can be done using the following commands:<\/p>\n
\r\n[root@rhel6 host0]# echo \"- - -\" > \/sys\/class\/scsi_host\/host0\/scan\r\n[root@rhel6 host0]# echo \"- - -\" > \/sys\/class\/scsi_host\/host1\/scan\r\n[root@rhel6 host0]# echo \"- - -\" > \/sys\/class\/scsi_host\/host2\/scan\r\n<\/pre>\nThe final step is to check the new hard disk \/dev\/sdb. This can be done using the following command:<\/p>\n
<root@rhel6 ~># fdisk -l<\/pre>\nAfter running this command, you should be able tosee the details of the new hard disk \/dev\/sdb, along with other disks on your server.<\/p>\n
Example:<\/p>\n
\r\n[root@rhel6 ~]# fdisk -l\r\n\r\nDisk \/dev\/sda: 12.9 GB, 12884901888 bytes\r\n255 heads, 63 sectors\/track, 1566 cylinders\r\nUnits = cylinders of 16065 * 512 = 8225280 bytes\r\nSector size (logical\/physical): 512 bytes \/ 512 bytes\r\nI\/O size (minimum\/optimal): 512 bytes \/ 512 bytes\r\nDisk identifier: 0x0000690f\r\n\r\n Device Boot Start End Blocks Id System\r\n\/dev\/sda1 * 1 64 512000 83 Linux\r\nPartition 1 does not end on cylinder boundary.\r\n\/dev\/sda2 64 1567 12069888 8e Linux LVM\r\n\r\nDisk \/dev\/dm-0: 10.2 GB, 10242490368 bytes\r\n255 heads, 63 sectors\/track, 1245 cylinders\r\nUnits = cylinders of 16065 * 512 = 8225280 bytes\r\nSector size (logical\/physical): 512 bytes \/ 512 bytes\r\nI\/O size (minimum\/optimal): 512 bytes \/ 512 bytes\r\nDisk identifier: 0x00000000\r\n\r\nDisk \/dev\/dm-0 doesn't contain a valid partition table\r\n\r\nDisk \/dev\/dm-1: 2113 MB, 2113929216 bytes\r\n255 heads, 63 sectors\/track, 257 cylinders\r\nUnits = cylinders of 16065 * 512 = 8225280 bytes\r\nSector size (logical\/physical): 512 bytes \/ 512 bytes\r\nI\/O size (minimum\/optimal): 512 bytes \/ 512 bytes\r\nDisk identifier: 0x00000000\r\n\r\nDisk \/dev\/dm-1 doesn't contain a valid partition table\r\n\r\nDisk \/dev\/sdb: 12.9 GB, 12884901888 bytes\r\n255 heads, 63 sectors\/track, 1566 cylinders\r\nUnits = cylinders of 16065 * 512 = 8225280 bytes\r\nSector size (logical\/physical): 512 bytes \/ 512 bytes\r\nI\/O size (minimum\/optimal): 512 bytes \/ 512 bytes\r\nDisk identifier: 0x00000000\r\n\r\nDisk \/dev\/sdb doesn't contain a valid partition table\r\n<\/pre>\nCommands Mentioned<\/h2>\n
\n
- ls \/sys\/class\/scsi_host<\/span> \u2013 This command is used to list the scsi_host values on your server.<\/li>\n
- echo “- – -” > \/sys\/class\/scsi_host\/hostX\/scan<\/span> \u2013 This command is used to rescan the SCSI Bus to add a SCSI Device without rebooting the VM. Replace ‘X’ with the number of the host.<\/li>\n
- fdisk -l<\/span> \u2013 This command is used to list the details of the disks on your server.<\/li>\n<\/ul>\n
Conclusion<\/h2>\n
Adding a new hard disk to your Linux RHEL 6 server without having to reboot it is a valuable skill for any web server administrator. It allows you to increase your server’s storage capacity without causing any downtime, which is crucial in a production environment. By following the steps outlined in this tutorial, you can easily add a new hard disk to your server.<\/p>\n
Remember, the type of hosting you choose, be it a dedicated<\/a>, or VPS<\/a> server, can also influence how you manage your server. Therefore, always ensure to choose the hosting type that best suits your needs.<\/p>\n
With the knowledge gained from this tutorial, you are now better equipped to manage your server effectively and efficiently. Keep exploring and learning, and you’ll become a web server administration expert in no time.<\/p>\n
FAQs<\/h2>\n
\n
- \n
What is the purpose of adding a new hard disk without rebooting?<\/p>\n
\n Adding a new hard disk without rebooting is essential in a production environment where downtime can lead to significant losses. It allows for increased storage space without disrupting the server’s operations.<\/span>\n <\/p>\n<\/li>\n
- \n
What does the command ‘ls \/sys\/class\/scsi_host’ do?<\/p>\n
\n The command ‘ls \/sys\/class\/scsi_host’ is used to list the scsi_host values on your server. These values are essential when rescanning the SCSI Bus to add a SCSI Device.<\/span>\n <\/p>\n<\/li>\n
- \n
What does the command ‘fdisk -l’ do?<\/p>\n
\n The command ‘fdisk -l’ is used to list the details of the disks on your server. It’s useful for verifying the addition of the new hard disk.<\/span>\n <\/p>\n<\/li>\n
- \n
Can this process be used on other Linux distributions?<\/p>\n
\n This process has been tested on Red Hat Enterprise Linux 6 (RHEL 6). It may also work on RHEL 5 and CentOS 5, but it’s always recommended to refer to the specific documentation of your Linux distribution.<\/span>\n <\/p>\n<\/li>\n
- \n
What is the significance of the VMware ESXi machine in this process?<\/p>\n
\n The VMware ESXi machine is the virtualization server in this context. It’s where the VM Guest, to which the new hard disk is being added, is hosted.<\/span>\n <\/p>\n
<\/<\/li>\n<\/ol>\n","protected":false},"excerpt":{"rendered":"
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