Categories
Company
Local Language
Forums
Discussions
Forums
- Data Protection and Retention
- Entry Storage Systems
- Legacy
- Midrange and Enterprise Storage
- Storage Networking
- HPE Nimble Storage
Discussions
Discussions
Discussions
Forums
Discussions
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
- BladeSystem Infrastructure and Application Solutions
- Appliance Servers
- Alpha Servers
- BackOffice Products
- Internet Products
- HPE 9000 and HPE e3000 Servers
- Networking
- Netservers
- Secure OS Software for Linux
- Server Management (Insight Manager 7)
- Windows Server 2003
- Operating System - Tru64 Unix
- ProLiant Deployment and Provisioning
- Linux-Based Community / Regional
- Microsoft System Center Integration
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Community
Resources
Forums
Blogs
- Subscribe to RSS Feed
- Mark Topic as New
- Mark Topic as Read
- Float this Topic for Current User
- Bookmark
- Subscribe
- Printer Friendly Page
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
10-20-2011 02:04 AM
10-20-2011 02:04 AM
LVM
please explain scenario use LVM vgexport and vgimport to safely mount a SAN volume from a RHEL 5 host (HOSTA) to another RHEL 5 host (HOSTB) in case if HOSTA crashes .
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
10-20-2011 09:00 AM
10-20-2011 09:00 AM
Re: LVM
In Linux LVM2 (which is the standard version in all modern Linuxes with kernel version 2.6+, including RHEL 5), vgexport and vgimport can only be used to avoid VG name conflicts when moving volumes from one host to another.
If you know that the VG names won't conflict, you can move the volumes without vgexport/vgimport: just move the disks to the other host. The udev subsystem will automatically run vgscan as it detects new disks, and vgscan will automatically recognize the added VG.
The Linux vgexport/vgimport commands are not useful in protecting a SAN volume that has been presented to two or more hosts simultaneously. When you run vgexport, the VG is marked as exported on the disk. So all the hosts accessing the disk will see it as "exported" on next vgscan. You cannot have the VG exported on one host, and imported on another if both hosts can see the volume(s): when you import the VG on HOSTA, the HOSTB will also see the VG as imported as soon as it runs a vgscan (e.g. when someone plugs in a USB stick to transfer some files).
(If you're familiar with HP-UX LVM, be aware that this is one of the points where Linux LVM is very different from HP-UX LVM.)
The old Linux LVM1 that was used with 2.4 and older kernels might have been different, but it's obsolete now.
If you want to automatically mount the SAN volume to HOSTB if HOSTA crashes, you need a failover cluster suite, e.g. RedHat Cluster. One of its features is a system that can prevent HOSTA from mounting the shared volumes if HOSTB has them mounted, or vice versa.If your RHEL 5 is updated to level 5.6 or better, this is provided by the clvmd daemons running on each cluster node and the "vgchange -ey <vgname>" command. In RHEL 5.5 and older, VG tags can be used for the same purpose.
Please see this RedHat Knowledge Base article:
https://access.redhat.com/kb/docs/DOC-3068
(RedHat Customer Portal access required)