Reclaim unused space on thin provisioned iSCSI LUN

iSCSI related applications
dspjones
First post
Posts: 1
Joined: Tue Jun 26, 2012 2:27 am

Re: Reclaim unused space on thin provisioned iSCSI LUN

Post by dspjones »

Realize this is an old post but thought it would be appropriate to post this here.

If you are running VMWare vSphere ESXi 5.5 or higher with a QNAP storage device running firmware 4.x or higher - reclaim is supported.
In my environment I have 2 QNAP TS-879U-RP's both with 8tb iscsi luns thin provisioned for storing backups. (1 at production site and the other in a DR site) We are running QNAP firmware 4.2 on them with vSphere ESXi 6.0 Update 1B
Both QNAPS show the LUN's as full, even though in Windows neither is using more than 4TB of the allocated space. At some point in the past the space usage ballooned up for whatever reason and subsequently that space is now shown as being in use from the QNAP's perspective.

So to reclaim the unused space all we had to do is the following:
On a host using qnap storage:

1. use putty or other ssh tool to login to the host
2. run the following command to find the pertinent info about your storage vmfs extents
esxcli storage vmfs extent list
3. You will get a list that should show you the Volume Name, VMFS UUID and some other info choose either the name or the UUID then run the following command:
esxcli storage vmfs unmap -u UUID NUMBER or
esxcli storage vmfs unmap -l VOLUME NAME (use ' ' if there are spaces)
4. Prepare for a long wait

In my case on my DR Qnap it took a couple of hours and I reclaimed over 3.6 TB of space and the LUN FULL message went away on the hardware display. The LUN was up during this process and no downtime was encountered.

*** However, that being said, vmware warns this process does tax the hardware somewhat and probably should be run during off hours. ***

Hope that helps anyone running vmware and qnaps with thin-provisioned iscsi luns.


For more info on this see this article:
https://kb.vmware.com/selfservice/searc ... Id=2057513
tchavei
Starting out
Posts: 13
Joined: Sun Nov 27, 2011 9:09 am

Re: Reclaim unused space on thin provisioned iSCSI LUN

Post by tchavei »

dspjones wrote:Realize this is an old post but thought it would be appropriate to post this here.

If you are running VMWare vSphere ESXi 5.5 or higher with a QNAP storage device running firmware 4.x or higher - reclaim is supported.
In my environment I have 2 QNAP TS-879U-RP's both with 8tb iscsi luns thin provisioned for storing backups. (1 at production site and the other in a DR site) We are running QNAP firmware 4.2 on them with vSphere ESXi 6.0 Update 1B
Both QNAPS show the LUN's as full, even though in Windows neither is using more than 4TB of the allocated space. At some point in the past the space usage ballooned up for whatever reason and subsequently that space is now shown as being in use from the QNAP's perspective.

So to reclaim the unused space all we had to do is the following:
On a host using qnap storage:

1. use putty or other ssh tool to login to the host
2. run the following command to find the pertinent info about your storage vmfs extents
esxcli storage vmfs extent list
3. You will get a list that should show you the Volume Name, VMFS UUID and some other info choose either the name or the UUID then run the following command:
esxcli storage vmfs unmap -u UUID NUMBER or
esxcli storage vmfs unmap -l VOLUME NAME (use ' ' if there are spaces)
4. Prepare for a long wait

In my case on my DR Qnap it took a couple of hours and I reclaimed over 3.6 TB of space and the LUN FULL message went away on the hardware display. The LUN was up during this process and no downtime was encountered.

*** However, that being said, vmware warns this process does tax the hardware somewhat and probably should be run during off hours. ***

Hope that helps anyone running vmware and qnaps with thin-provisioned iscsi luns.


For more info on this see this article:
https://kb.vmware.com/selfservice/searc ... Id=2057513
Hi

I just logged in to thank you for this tip! It just saved me. Qnap was reporting 99% lun usage and I knew it was wrong because vmware was reporting the drive as having over 20% free space. Ran your commands and voila... my NAS now reports correctly 73% usage! :)

Now I wish I knew how to solve another lun with the same issue but connected to windows server (2k8)... same story. NAS reports 95% usage while the server reports (correctly) 75% usage.
cw1972
New here
Posts: 3
Joined: Tue Aug 01, 2017 6:55 pm

Re: Reclaim unused space on thin provisioned iSCSI LUN

Post by cw1972 »

dspjones wrote:Realize this is an old post but thought it would be appropriate to post this here.

If you are running VMWare vSphere ESXi 5.5 or higher with a QNAP storage device running firmware 4.x or higher - reclaim is supported.
In my environment I have 2 QNAP TS-879U-RP's both with 8tb iscsi luns thin provisioned for storing backups. (1 at production site and the other in a DR site) We are running QNAP firmware 4.2 on them with vSphere ESXi 6.0 Update 1B
Both QNAPS show the LUN's as full, even though in Windows neither is using more than 4TB of the allocated space. At some point in the past the space usage ballooned up for whatever reason and subsequently that space is now shown as being in use from the QNAP's perspective.

So to reclaim the unused space all we had to do is the following:
On a host using qnap storage:

1. use putty or other ssh tool to login to the host
2. run the following command to find the pertinent info about your storage vmfs extents
esxcli storage vmfs extent list
3. You will get a list that should show you the Volume Name, VMFS UUID and some other info choose either the name or the UUID then run the following command:
esxcli storage vmfs unmap -u UUID NUMBER or
esxcli storage vmfs unmap -l VOLUME NAME (use ' ' if there are spaces)
4. Prepare for a long wait

In my case on my DR Qnap it took a couple of hours and I reclaimed over 3.6 TB of space and the LUN FULL message went away on the hardware display. The LUN was up during this process and no downtime was encountered.

*** However, that being said, vmware warns this process does tax the hardware somewhat and probably should be run during off hours. ***

Hope that helps anyone running vmware and qnaps with thin-provisioned iscsi luns.


For more info on this see this article:
https://kb.vmware.com/selfservice/searc ... Id=2057513
This is amazing! I've been looking for something like this for months.

Three times now my iSCSI LUN has reported full in QNAP whereas vSphere / ESXi tells me the truth and I have resorted to copying data off, deleting and recreating the LUN which was highly annoying.

I want to buy you a beer :)
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storageman
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Joined: Thu Sep 22, 2011 10:57 pm

Re: Reclaim unused space on thin provisioned iSCSI LUN

Post by storageman »

The moral is don't use thin LUNs if you can help it.
P3R
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Joined: Sat Dec 29, 2007 1:39 am
Location: Stockholm, Sweden (UTC+01:00)

Re: Reclaim unused space on thin provisioned iSCSI LUN

Post by P3R »

I think the moral is, if you need/want thin storage allocation, make sure you understand how it really works before implementing (at least in any larger scale).

Thick is easy if you have a deep wallet, thin is much more complicated to manage well. Take your pick depending on your personal limitations.
RAID have never ever been a replacement for backups. Without backups on a different system (preferably placed at another site), you will eventually lose data!

A non-RAID configuration (including RAID 0, which isn't really RAID) with a backup on a separate media protects your data far better than any RAID-volume without backup.

All data storage consists of both the primary storage and the backups. It's your money and your data, spend the storage budget wisely or pay with your data!
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