I think you're thinking of snap reserve, which is an entirely different beast.
Fractional reserve is set to 100% by default. The reason for this is to set aside enough space if you were to overwrite an entire lun. If that happened, your snapshot would be as large as the lun itself. Now, every environment is different, so you can adjust the fractional reserve accordingly, but NetApp best practice is to leave it at 100%.
-----Original Message----- From: Borzenkov, Andrey [mailto:Andrey.Borzenkov@fujitsu-siemens.com] Sent: Tuesday, December 04, 2007 1:50 AM To: Holland, William L; Raj Patel Cc: Milazzo Giacomo; toasters@mathworks.com Subject: RE: Can't expand SnapDrive for Windows drive
You should understand implications of it. Fractional reserve allows you to cheat. But if you set it to 10% and in reality need 20%, writing to LUN will fail unless snapshots are deleted (can be done automatically in new versions).
С уважением / With best regards / Mit freundlichen Grüβen
--- Andrey Borzenkov Senior system engineer -----Original Message----- From: owner-toasters@mathworks.com [mailto:owner-toasters@mathworks.com] On Behalf Of Holland, William L Sent: Monday, December 03, 2007 9:25 PM To: Raj Patel Cc: Milazzo Giacomo; toasters@mathworks.com Subject: RE: Can't expand SnapDrive for Windows drive
You can lower it. vol options <volname> fractional_reserve xx
-----Original Message----- From: Raj Patel [mailto:phigmov@gmail.com] Sent: Monday, December 03, 2007 1:02 PM To: Holland, William L Cc: Milazzo Giacomo; toasters@mathworks.com Subject: Re: Can't expand SnapDrive for Windows drive
The default is to have a volume at least twice the size of a LUN to
accomodate at least one full snapshot.
I have heard the new versions of DataOntap and SnapDrive allow for a lower ratio - I'm guessing you can't retrospectively upgrade and reduce the space allocation on existing volumes ?
Or have I misheard the capabilities of the new versions ?
Cheers, Raj.