LUN Space Reclamation

[#1]

Hello,

I am facing an issue in a customers environment. They have a physical Windows Server 2008, accessing a LUN via FCP on a V3270.

They are not using snapdrive. The behavior on this LUN is to write a bunch of files and then delete them. This LUN is showing as 99% occupied on DOT 8.1.

If we check the Windows Server point of view, there is more than 50% of available space.

I imagine that this is a situation where space reclamation could be used, right? The DOT does not understand deleted files as free space since Windows did not informed this when they were deleted.

Question 1: Will I be able to continue to write in this LUN, even if DOT shows me no space available?

Question 2: The only way to reclaim space is through snapdrive? If I dont, will DOT alarm me til the end of times that there is no space available on the LUN?

Kind regards,

Pedro Rocha.

[#2]

Please copy and paste exact command and its output where you see LUN as 99% occupied. I am not sure what it means and would rather avoid guesswork.

By default Netapp reserves enough space so writes to LUN should never fail due to lack of space on volume. If you changed to thin provisioning, LUN will go offline when there is no space for new writes. You are responsible for monitoring free space and take measures if it becomes low. Again - this is free space on volume. How much free space is reserved depends on whether you use snapshots and/or deduplication or not.

[#3]

Please consider no dedup or snapshot.

Consider also volume space garantee and space reserved luns.

A LUN shown by system manager for instance as 99% used is still writable, right (considering that on guest os this LUN is not 99% used)?

I guess it is just a matter of how dot it seeing used space inside de LUN. And from what I have seen, the only way to reclain free space on a previously written LUN is using snapdrive. Is that right?

Regards,

Pedro Rocha.

Enviado pelo meu aparelho BlackBerry® da Vivo

[#4]

If volume space guarantee and lun space reserved, NetApp ensures enough space is reserved for writing to LUN. With snapshots, default fractional reserve is 100% which again ensures that there is always space for LUN overwrites (or snapshot creation would fail). To be honest, I have no idea how OC SM measures LUN usage, nor do I use it (except if customer asks me to show how to setup it ☺ ).

Yes, I am not aware of any other supported method to perform space reclamation under Windows; you need SnapDrive to do it.

[#5]

There is second way to reaclaim space. With use of ONTAP PowerShell Toolkit, you can do this without installing SnapDrive and also much faster (in 2TB LUN, 800GB free space was reclaimed in 80 minutes!)

Here are some commands you might find useful:

#Import modules to PowerShell

Import-Module DataONTAP

#Connect to filer

Connect-NaController x.y.z.a -Credential (Get-Credential)

#List all disks on host with path on ONTAP

Get-NaHostDisk

#Start reclaiming space

Invoke-NaHostVolumeSpaceReclaim X:\

Regards,

Matjaž

[#6]

This effectively implies native support for space reclamation in windows. I am curious, which Windows version do you have?

Отправлено с iPhone

02.12.2012, в 22:32, "Matjaz Znidar" <xdl-communities@communities.netapp.com<mailto:xdl-communities@communities.netapp.com>> написал(а):

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Re: LUN Space Reclamation

created by Matjaz Znidar<https://communities.netapp.com/people/UCB-NETAPP> in Storage Systems - View the full discussion<https://communities.netapp.com/message/95816#95816>

There is second way to reaclaim space. With use of ONTAP PowerShell Toolkit, you can do this without installing SnapDrive and also much faster (in 2TB LUN, 800GB free space was reclaimed in 80 minutes!)

Here are some commands you might find useful:

#Import modules to PowerShell

Import-Module DataONTAP

#Connect to filer

Connect-NaController x.y.z.a -Credential (Get-Credential)

#List all disks on host with path on ONTAP

Get-NaHostDisk

#Start reclaiming space

Invoke-NaHostVolumeSpaceReclaim X:\

Regards,

Matjaž

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[#7]

We are using this on WIndows 2008R2 in production and on Windows 2012 in test environment.

I made also additional tests and can confirm, that SpaceReclaim is running only about 1 minute if there is nothing to reclaim. So I think it is safe to use it on regular basis (as scheduled job).

Regards,

Matjaž

[#8]

I am not surprised about 2012 which has official native support for space reclamation, but it is quite interesting to see that 2008R2 also works. Do you have any statements from Microsoft regarding this? I mean, as long as it is undocumented feature, I would never recommend using it in production.

[#9]

I admit, you put me on doubt.

At the moment I have no windows 2008R2 without DSM manager installed, but I can test in our lab in the afternoon.

Regards,

Matjaž

[#10]

As promised, I tested space reclamation on Windows 2008R2 without DSM installed and it worked as good as on Windows 2012.

I hope this helps you.

Kind regards,

Matjaž