When we want to use a disk in Veritas Volume Manager at that time we need to write a disk signature on disk which is a VERITAS proprietary. This process will divide the disk into two parts which are defined as Private Region and Public Region.
Public Region is a section where you can store data in a volume.
Private Region is a section which occupies about a 1 MB of space but it holds some important and critical configurations, whatever configuration we do with a disk by adding it in a Dynamic DG and creating a volume those information’s are stored in that section.
Today I will show you there was a disk failure and from a utility called vmtool from there we can fetch the disk header information to check disk still holds the Private Region information on a disk or its got corrupted.
In the above image you can there are two disks as Harddisk3 and Harddisk4 which is affected and shows as failed
In this case you need to ensure the disk is detected by the OS or not for that you need to go to Devices Manager and check the storage section there you must see the devices.
If there are devices which are forming the volume which is down – then you may use a utility to check that Disk Private region is corrupted or ok. Name of the tool is vmtool…
In the above image you can see – this vmtool is able to fetch the information from the Private Region as we can see the DG name as datadg but its unable to get the Disk ID information.
Then i checked the luns from the storage end and found somehow the luns was in a mode which was Write Protected due to which we are unable to control it from the OS. Then i turned off that mode and after that i have brought the disk and volume up again and ran the utility again to see the difference…
Now you can see we can see the disk ID information
This tool is very handy and must test the command and switch in test servers first as we are not responsible on your action performed on Production Servers.
These are commands – Thanks please put your comments