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EMC SAN LUN extended but the server can't see the expanded LUN space
I have a Windows 2008 R2 Ent server which has an NTFS D-drive which was a 1200GB LUN on our EMC VNX5300 SAN. The DBAs asked one of the Systems team members to increase the LUN so that the WIndows partition could be increased to accomodate the growing database. The D-Drive is an MBR style partition.
The Systems guy increased the LUN on the SAN to 2050GB but when he looked on the server, the available disk space in Disk Manager has not changed- there is no extra disk space to increase the partition on?
I'm not sure what is going on. Normally when you expand a LUN the extra space is visible in Windows Disk Manager.
dynamox
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September 18th, 2017 08:00
anything >2TB has to be GPT.
Understanding the 2 TB Limit in Windows Storage | Ask the Core Team
JulianMilano
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September 18th, 2017 15:00
Agreed, but if we are talking about partitions. Normally, when I have, say, a 1TB LUN with a 1TB Windows partition, and I extend the LUN to say 3TB, Windows should show me a 3TB disk, with a 1TB partition, and since it is an MBR style partition, it should only let me extend the partition to 2TB and after that, still showing me 1TB which I could make another 1TB partition.
In this case I cannot see the extended LUN at all in Windows!?
Oh, it's a Windows Failover cluster disk in case that makes a difference?
dynamox
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September 19th, 2017 06:00
I see your point, can you move that disk cluster resource between nodes and see if anything changes ?
JulianMilano
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September 19th, 2017 23:00
Nah, doesn't work.
So I mirrored the drive on the same SAN and presented the mirror-copy to another server but as a 2500GB LUN and instantly I could see the disk, broken into the following:
* Partition 1 : 1200GB (formatted and used)
* Box 1: 848GB unused
* Box 2: 452GB unused
I was then able to extend partition 1 so now I have the following:
* Partition 1 : 2048GB (formatted and used)
* Box 2: 452GB unused
Interestingly, note the maximum size of the partition? 2048 - which is 2 bytes less than the allocated space on the original LUN!! I cannot do anything with the 452GB space as the MBR disk does not support more than 2TB, or should I say 2048GB, partitions!
dynamox
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September 20th, 2017 03:00
sure sounds like cluster services have a lock or some kind of reservation on the disk and won't let you expand it.
ApurvaGupta
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October 3rd, 2017 18:00
This is an issue with Windows 2008 server r2. I had the similar problem where I extended a VNX disk beyond 2 TB and the entire server crashed. We had to rebuild it from backup.
I believe its the MBR limitation, make a new 2TB GPT disk and migrate the data off the original disk