Snapdrive and fractional reserve

[jvdrenth]

NetApp friends,

I have a question about snapdrive and the ever looming bug bear called fractional reserve.

After attending the NetApp SE event I was assured that the old sizing paradigm of 2x +Delta is no longer the only way to safely deliver LUNs onto our faithful user base. The idea being to thin provision (no reserve) the Volume and LUN, put autodelete on snap reserve boundaries and monitor the amount of free space.

Alas as I have now found out first hand snapdrive 6.0.1 when creating a LUN doesn't offer any means of keeping things lean and mean and puts a 100% fractional reserve on the volume.

I have seen some new documentation stating things should be able to be kept thin without fractional reserve but the question now is how do we implement that with snapdrive and subsequently snapmanager. Secondly where in the tangled mass that is netapp documentation is the latest and greatest on this subject because I have seen a lot of contradiction in TR's, manuals and whatnot.

[jvdrenth]

Some testing on this made me somewhat confused, having a non reserved LUN and volume results in a fractional reserve of 100%. I can import this into snapdrive and have a sdparams.conf file with no reservation setting on.  But now it looks like if I take snapshots there is no additional data being reserved as I would expect because of the fractional reserve.

Now it looks like I get what I want, but I don't get how or why...

Anyone have a flashligt?

[bteterin]

Hi,

Please check these documents about NetApp Thin Provisioning strategy and recommendations. You will find fractional reservation information and SDW support for it as well, but the most important information is to how configure and manage Thin Provisioning.

http://www.netapp.com/library/tr/3483.pdf

http://www.netapp.com/library/tr/3563.pdf

Thanks,

Boris.