How to resize a snapmirror volume?

[marcconeley]

Hi Everyone,

Can someone point me to instructions on how to resize a SnapMirror volume?

We have a 600Gb volume that we are mirroring from a FAS2020 in SiteA, to a FAS2020 in SiteB for backup.

Today I had to resize the primary volume in SiteA as it was running low on space. However, when I try to resize the mirror of this volume in SiteB it gives an error because the volume is "read only".

I've heard that the correct way of doing this is disabling the mirror, change the read-only state on the SiteB mirror via the command line, resize the volume, mark it read-only again and then restart SnapMirror - any ideas on how to actually achieve this would be great!

(and there I was thinking I'd quickly resize both volumes and "hey presto" everything would take care of itself! ).

Thanks,

Marc

[danielpr]

Marc.

You cant resize the mirrored volume (read-only), You need to break the mirror and if you wish you can try that using FilerView for mirror break & volume resize.

Below the steps you can follow in this case

FAS2020 in SiteA, to a FAS2020 in SiteB

1) Break the mirror on FAS2020 in SiteB

2) Resize the volume of FAS2020 in SiteA

3) Resize the FAS2020 in SiteB backup Volume with same size of volume FAS2020 in SiteA primary volume

    (You can keep the destination much higher in space.)

4) Backup volume FAS2020 in SiteB should be in offiline mode

5) Now Intialize the sanpmirror on FAS2020 in SiteB

Thanks;

Daniel Prakash

[marcconeley]

Hi Daniel,

I tried your steps but still the "mirror" of the volume in SiteB - even with SnapMirror disabled - says it's "read-only" and won't allow me to resize it.

How can I make the volume not read-only so that resizing is allowed?

It doesnt seem possible through the web GUI?

Thanks,

Marc

[mikepapalia]

Marc,

Go to the command line and type "vol online volname". When you are done resizing, return the volume to a restricted state by entering: "vol restrict volname"

[marcconeley]

Hi Mike,

When I run this command it tells me that the volume is already online. I can take it offline/online using the web GUI - but either way it won't let me change it's volume size because it's marked as "read-only".

So, if vol restrict [volname] restricts the volume (which I guess is the same as read-only), then what is the opposite command to unrestrict it?

Sorry for the confusion.

Marc

[mikepapalia]

This makes it seem like the mirror is not broken (?.. what does "snapmirror status" tell you) Just to be sure, you have done a "snapmirror break" (after a "snapmirror quiesce") on the destination system? Then did the vol online command. And still no luck?..

[marcconeley]

Hi Mike,

OK, it seems that I am getting a little further with this now (a guide would be great if anyone knows of one):

So it seems that I did not correctly "break" the mirror in SiteB (I simply disabled snampmirror instead of a quiesce then break).

I've now correctly broken the mirror and the state in snapmirror = "broken off". So I assume this part is now correct.

The volume in SiteB is now no longer marked as read-only, and can be taken online and offline fine. But now when I try to resize the volume I get this error message:

java.io.IOException: Failure resizing volume SM_BNK_Userfiles: Volume has a fixed filesystem size (fs_size_fixed)

Any ideas?

Thanks for the help so far.

Marc

[danielpr]

Marc,

Can you please share the following answers

Check if SIS (Dedupe) is enabled on the primary volume ?

Which version of Data ONTAP release is running on the filer?

Thanks
Daniel

[marcconeley]

Both filers are running OnTap version: 7.2.4L1

(we will upgrade to 7.3.1 on the 19/02/09).

We are not running SIS on any of the volumes (the primary volume in SiteA, or the mirrored volume in SiteB).

Marc

[danielpr]

Marc-

Please check if the  fs_fixed_size is turned off. If its off then change to on using the
following command

#vol options <volumename> fs_size_fixed on

After setting this try to resize the volume.

Thanks
Daniel

[mikepapalia]

Also, the guide you seek is the Data Protection Online Backup and Recovery Guide : )

You can also do a man snapmirror from the command line or go to Documentation from within FilerView.

[marcconeley]

Daniel,

Yes fs_size_fixed was ON. I turned it off and was then able to finally resize the volume.

Next problem:

- I resized the volume (good).

- Tried to initialise the snapmirror again (in SiteB) and it said "destination volume must be restricted..".

- I ran vol restrict [volname] and restricted the volume as it was before.

- Went back into the SnapMirror settings and initialised the mirror again on the destination (state until this point was still = "broken off").

Now something weird has happened because it appears the entire mirrored volume (all 650Gb) in SiteB has vanished!

I can't see the volume through the command line or GUI.

Any ideas what's happening here?

[marcconeley]

Some more info: vol status from the command line tells me: [volname] is temporarily busy (snapmirror destination).

Would this suggest that everything will return to normal once it's finished initializing?

And I hope "initializing" doens't mean it's recreating the mirror from scratch? i.e. copying down all 650Gb?

[danielpr]

Marc-

While snapmirror transfer happens the volume will be in busy state.
You can find the snapmirror transfer rate in Filerview Snapmirror Report page.


PS:

Volume size is being retained for potential snapmirror resync. 
If you would like to grow the volume and do not expect to resync,
then only you should set vol option fs_size_fixed to off.



Thanks
Daniel

[marcconeley]

PS:

Volume size is being retained for potential snapmirror resync. 
If you would like to grow the volume and do not expect to resync,
then only you should set vol option fs_size_fixed to off.

- Before I clicked to re-initialize the mirror I didnt turn this option on again (it's still turned off).

Is this going to cause a problem?

Should I "abort" the current mirror operation, turn on this option again and then initialize the mirror?

I am starting to panic

[chriskranz]

Just read through the post, and you seem to have been taken around the houses a little! I'll give you a quick guide on resizing a SnapMirror destination.

To resize your destination volume

1) Quiesce the SnapMirror destination (command line: "snapmirror quiesce vol_name")

2) Break the SnapMirror relationship (command line: "snapmirror break vol_name")

3) Disable Fixed FS Size (command line: "vol options vol_name fs_size_fixed off")

4) Grow the volume (command line: "vol size vol_name +size_to_grow")

5) resync the snapmirror (command line: "snapmirror resync vol_name")

Don't re-initialize (that'll re-baseline it!), and don't worry about A-SIS settings. Once a volume has been SnapMirrored, you shouldn't need to restrict it again, this is only for re-initializing (which you shouldn't need to do).

This whole thing can be a little tedious and quickly gets a bit annoying if you grow your volumes regularly. Can I recommend that you thin provision your SnapMirror destination volumes? Set the volume size to the maximum space you have in your aggregate, but set the space guarantee to "none". Then when you do a SnapMirror initialize (or indeed resync it if it already exists), this setting is over-written and the size is fixed (fs_size_fixed) using SnapMirror. As the source volume grows, the destination will also grow.

The only thing you have to watch out for here is if you have more space on your source than your destination, you could end up filling up the destination entirely, so just keep an eye on that.