Snapshots

Snapshots are a implementation of copy on write that allows for a file system to quickly take a point in time copy of the file system and provide access to the data through a .snapshot directory.

We provide Snapshots on our ONStor, Nexenta and FluidFS filers to certain file systems.

Please see SnapshotFileSystems for a list of our file systems that have snapshots in the department.

Snapshot Policy

Our core file systems in the department are on a 4 hour snapshot cycle. Snapshots are taken at,

12am

4am

8am

12pm

4pm

8pm

We retain up to 8 hourly snapshots, 2 daily snapshots and 1 weekly snapshot.

The OpenLAB filesystems on which snapshots are available are listed on the SnapshotFileSystems page.

Snapshot Restoring

If you have deleted a file by mistake and you need to get it back, you can use the snapshots directory to recopy the file. This directory can typically be found in your home directory; it will be prepended by a ., so you will need to use the command "ls -a" to find it. It will be one of three:

• .snapshot for the ONStor (will be removed soon!) / NetApp filers
• .snapshots for the FluidFS filer
• .zfs/snapshots for the Nexenta / ZFS filers

The inside of one of these will look something like:

An example:

Changing to my quotes directory.

[derek@novelty quotes]$ pwd
/nfshomes/derek/work/quotes

I see that i have a quote called redhat_sole_source_2007.doc.

[derek@novelty quotes]$ ls
dlt_pdf_quote2007.pdf  Quote_300086759.html         redhat_solesource.pdf
dlt_pdf_quote.pdf      Quote_353511914.html         soleSource2007.pdf
dlt_quote.pdf          Quote_367512608.html         soleSource.pdf
dy1014.xls             Quote_367884529.html         UMD_008.xls
Quote_250530976.html   redhat_sole_source_2007.doc

[derek@novelty quotes]$ ls -la redhat_sole_source_2007.doc 
-rw-r--r-- 1 derek derek 39936 Jan 23  2007 redhat_sole_source_2007.doc

I will remove it from the current file system.

[derek@novelty quotes]$ rm redhat_sole_source_2007.doc 

As you can see it no longer is there.

[derek@novelty quotes]$ ls 
dlt_pdf_quote2007.pdf  Quote_250530976.html  Quote_367884529.html   UMD_008.xls
dlt_pdf_quote.pdf      Quote_300086759.html  redhat_solesource.pdf
dlt_quote.pdf          Quote_353511914.html  soleSource2007.pdf
dy1014.xls             Quote_367512608.html  soleSource.pdf

I am going to go into the last hourly snapshot hourly.0

[derek@novelty quotes]$ cd .snapshot/hourly.0

As you can see the quote is still here.

[derek@novelty hourly.0]$ ls
dlt_pdf_quote2007.pdf  Quote_300086759.html         redhat_solesource.pdf
dlt_pdf_quote.pdf      Quote_353511914.html         soleSource2007.pdf
dlt_quote.pdf          Quote_367512608.html         soleSource.pdf
dy1014.xls             Quote_367884529.html         UMD_008.xls
Quote_250530976.html   redhat_sole_source_2007.doc

I copy it back to the original directory.

[derek@novelty hourly.0]$ cp redhat_sole_source_2007.doc /nfshomes/derek/work/quotes/

Change back to the original directory.

[derek@novelty hourly.0]$ cd /nfshomes/derek/work/quotes/

And it is back.

[derek@novelty quotes]$ ls
dlt_pdf_quote2007.pdf  Quote_300086759.html         redhat_solesource.pdf
dlt_pdf_quote.pdf      Quote_353511914.html         soleSource2007.pdf
dlt_quote.pdf          Quote_367512608.html         soleSource.pdf
dy1014.xls             Quote_367884529.html         UMD_008.xls
Quote_250530976.html   redhat_sole_source_2007.doc