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francis.favorini
Forum Admin
USA
618 Posts |
 Posted - Jan 05 2004 : 5:14:14 PM
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Folks,
As NetApp filers, Hodgkin, Huxley and Katz both have a useful feature you may not be aware of that can help you restore accidentally deleted or overwritten files. Periodically, a snapshot of all files on each system is taken. A snapshot is a frozen, read-only image of the entire file system and reflects the state of the all files at the time the snapshot was created.
Snapshots are taken according to the following schedule:
- Hourly snapshots are taken every day at 8am, 12pm, 4pm, and 8pm and the six most recent snapshots are saved.
- Nightly snapshots are taken every night at midnight, and the two most recent snapshots are saved.
- Weekly snapshots are taken every Sunday at midnight, and the most recent snapshot is saved.
Every directory in the file system contains a special, hidden directory named ~snapshot which you can use to access the old versions of files in that directory. Within the ~snapshot directory are directories named hourly.1, nightly.2, weekly.0 and the like. These contain the hourly, nightly and weekly saved snapshots. Those with .0 extensions are the most recent snapshots of that type, those with .1 are the next most recent, and so on. For example, on our systems, nightly.1 is from two nights ago, weekly.0 is from last week.
Examples:
- You accidentally deleted a file (\\Huxley\Data\Exp.01\Analysis\important.txt). The file was last changed yesterday. To restore that file, simply copy \\Huxley\Data\Exp.01\Analysis\~snapshot\nightly.0\important.txt back to where it was.
- At 2pm, you deleted \\Huxley\Data\Exp.01\Notes\todo.txt which was created early this morning and last updated at 11am. It is now 5pm. You can choose from the following snapshots to restore from \\Huxley\Data\Exp.01\Notes\~snapshot:
- hourly.0 taken at 4pm, will not have todo.txt
- hourly.1 taken at 12pm will have the latest version
- hourly.2 taken at 8am will have an old version of the file
- hourly.3, hourly.4, and hourly.5 will not have todo.txt
- You realize that a file was accidentally updated with the wrong information during the week. You can restore last week's version by copying it from the ~snapshot\weekly.0 directory.
Notes:
- On Unix systems, you must use .snapshot to refer to the snapshot directory.
- To restore any file from a snapshot, just copy it from the snapshot directory to where you want it to go, which may or may not be its old location.
- Snapshot files carry the same permissions as their corresponding current files. Only users who have permission to read the current version of the file can read that file in a snapshot.
- You cannot delete or write to a snapshot version of a file. All snapshots are read-only.
- To compare an old version of a file with the current version, you don't need to copy the old version, just use the ~snapshot path to refer to it.
-Francis
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IT Director, Brain Imaging and Analysis Center |
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diaz
BIAC Alum
USA
212 Posts |
Posted - Sep 01 2004 : 2:44:52 PM
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| Does Nernst have snapshot backups available? If not, can it be made to have them (like hodgkin and huxley)? |
Michele T. Diaz, Ph.D.
Associate Director
Brain Imaging and Analysis Center |
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francis.favorini
Forum Admin
USA
618 Posts |
Posted - Sep 03 2004 : 11:39:03 AM
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Nernst does not have Snapshots, since it is not a NetApp filer. There is a similar feature that we are looking into enabling, however. I will post any updates to the forum.
-Francis
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IT Director, Brain Imaging and Analysis Center |
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Snapshots on NetApp servers
