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5 Posts
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2570
November 27th, 2013 02:00
VNXe 3100 Free Space not available to all LUNS
My VNXe 3100 is setup with one large storage pool of 10 disks
I have ISCSI servers on SPA and SPB. There is 300 gig of free space but when I try to extend a LUN on each server I get
10 Gig available on ISCSI server A
290 Gig available on ISCSI server B
Why is this ? Why can the space not be equally claimed by either ISCSI server/SP ?
There is no protection configured. Is there some kind of reserve setting somewhere ?
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DELL-Leo
Community Manager
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9K Posts
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November 27th, 2013 23:00
Hey,
You can easily to understand the issue.
Storage servers are tied to a specific storage processor (SP). Based on the storage server you select, a list of available storage pools appears. When space is allocated for storage resources on specific storage servers, additional space gets reserved which can then be only used by the storage servers on that SP. The available space displayed in the list of storage pools is the space generally available to the storage servers on either storage processor (unreserved space) and any available space that is reserved for the storage server's SP. This is why you may notice that the free space in a storage pool is different for storage servers on SPA and SPB.
Hope this helps.
VNxe
16 Posts
0
November 27th, 2013 07:00
Hi
There is something called Global Pool which is accessible to both SPs. Also there is Local Pool for each SP separately. Whenever administrator requests for storage depending on size requested some space is allocated to Local Pool from Global Pool. The amount of space allocated to Local Pool totally depends on requested space. Usually it is more than what is requested to have a buffer for headers and auto-extension.
Also when some storage is deleted it is not immediately released to Global Pool. So, there will be some free space available in Global Pool and also in Local Pool of each SP.
The free space shown in Storage Pool properties is collective free space of Global Pool and both Local Pools. Where as in the storage creation wizard it shows free space of Global Pool+free_space_of_Local_Pool_of_that_SP.
I hope aforementioned explanation clears your doubt.
SSFMCHC
5 Posts
0
November 27th, 2013 13:00
Is there anyway to claim the space back from a local pool, back into the global pool I could really do with that space on the other SP ?
SSFMCHC
5 Posts
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November 28th, 2013 01:00
So basically if I wanted an even spread of the spare disk space I would need to delete all LUNS and both ISCSI servers and start again to make sure I am getting an even share from the global pool or would one end up bigger than the other anyway because the first one I create will put some of the global space into the local pool reserve ?
chrislogo
98 Posts
0
November 30th, 2013 06:00
Below KB article will help understand the Global Pool and Local Pool concept in VNXe
Article Number:000078815
https://support.emc.com/kb/78815