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 filers to certain file systems.

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.

Snapshot Restoring

If you find that you have mistakenly deleted a file and it was created/written to before the last snapshot[1]. You can restore the file by going to the directory where the file was and changing into the .snapshot directory and then using a normal copy operation to copy it back to the directory where you would like it. Please note that the .snapshot directory is hidden and may not appear when you do a directory listing.

• [1] - If a file was created or modified after the last snapshot then you can potentially lose up to 4 hours of work in a worse case scenerio. Please make sure you save your work throughout the day.

Example:

<verbatim> [derek@novelty quotes]$ pwd /nfshomes/derek/work/quotes [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 [derek@novelty quotes]$ rm redhat_sole_source_2007.doc [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 [derek@novelty quotes]$ cd .snapshot/hourly.0 [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 [derek@novelty hourly.0]$ cp redhat_sole_source_2007.doc /nfshomes/derek/work/quotes/ [derek@novelty hourly.0]$ cd /nfshomes/derek/work/quotes/ [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 </verbatim>