A volume level snap restore is near instantaneous as it simply has to change the active bit map table. However, what you are doing is a single file snap restore. There is more work involved in determining what blocks are used by that file. So, what NetApp does is basically a clone then split operation. This gives you access to the file almost instantaneously while it splits off the clone. They can't simply modify the bit map table as they do in volume level snap restores because you may otherwise lose the ability to restore later volume snapshots that also had that file referenced within them.
On Mon, Feb 4, 2013 at 4:23 AM, Avi Ben Emanuel (Wollman) avi@jct.ac.ilwrote:
marketing continuously claim that snap restore is instantaneous. yet I have yet to succeeded doing so. "snap restore" of files to a location quite a while and is "copying the files" nothing close to instantaneous. i would be happy to understand what i am missing. the following is a example of a virtual disk that was restored, it took quite a while to "restore"=copy this 80gb file.
snap restore -t file -s nightly.0 /vol/vmsata/vmfs1/lms-client/lms-clinet-flat.vmdk
Avi
Avi Ben Emanuel (Wollman) (אבי בן עמנואל (וולמן Systems Engineer | Unix Microsoft Vmware Jerusalem College of Technology מחלקת תקשוב בית הספר הגבוה לטכנולוגיה - מכון לב POB 16031 Jerusalem 91160 Israel הועד הלאומי 21 ירושלים Email: avi@jct.ac.il | Office: +972-2-6751036 | Mobile: +972-52-3809107
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