https://wiki.umiacs.umd.edu/umiacs/api.php?action=feedcontributions&feedformat=atom&user=DalaroUMIACS - User contributions [en]2026-04-04T03:41:52ZUser contributionsMediaWiki 1.43.7https://wiki.umiacs.umd.edu/umiacs/index.php?title=Snapshots&diff=3849Snapshots2011-01-19T18:38:39Z<p>Dalaro: sp</p>
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<div>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.<br />
<br />
We provide [[Snapshots]] on our [[ONStor]] filers to certain file systems.<br />
<br />
==Snapshot Policy==<br />
<br />
Our core file systems in the department are on a 4 hour snapshot cycle. Snapshots are taken at,<br />
<br />
{| style="color:green; background-color:#ffffcc;" cellpadding="5" cellspacing="0"<br />
| 12am<br />
| 4am<br />
| 8am<br />
| 12pm<br />
| 4pm<br />
| 8pm<br />
|}<br />
<br />
We retain up to 8 hourly snapshots, 2 daily snapshots and 1 weekly snapshot.<br />
<br />
These are available on the following [[OpenLAB]] file systems,<br />
<br />
===[[NFS]]===<br />
* /nfshomes<br />
* /fs/www<br />
* /fs/www-users<br />
* /fs/ftp<br />
<br />
===[[CIFS]]===<br />
* \\umiacsfs02.umiacs.umd.edu\nfshomes<br />
* \\umiacs-webftp.umiacs.umd.edu\www-umiacs<br />
* \\umiacs-webftp.umiacs.umd.edu\www-users<br />
* \\umiacs-webftp.umiacs.umd.edu\ftp-umiacs<br />
<br />
Please see [[SnapshotFileSystems]] for a list of our file systems that have snapshots in the department.<br />
<br />
==Snapshot Restoring==<br />
<br />
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.<br />
<br />
''[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 scenario. Please make sure you save your work throughout the day.''<br />
<br />
Example:<br />
<br />
Changing to my quotes directory.<br />
<pre><br />
[derek@novelty quotes]$ pwd<br />
/nfshomes/derek/work/quotes<br />
</pre><br />
I see that i have a quote called '''redhat_sole_source_2007.doc'''.<br />
<pre><br />
[derek@novelty quotes]$ ls<br />
dlt_pdf_quote2007.pdf Quote_300086759.html redhat_solesource.pdf<br />
dlt_pdf_quote.pdf Quote_353511914.html soleSource2007.pdf<br />
dlt_quote.pdf Quote_367512608.html soleSource.pdf<br />
dy1014.xls Quote_367884529.html UMD_008.xls<br />
Quote_250530976.html redhat_sole_source_2007.doc<br />
</pre><br />
<pre><br />
[derek@novelty quotes]$ ls -la redhat_sole_source_2007.doc <br />
-rw-r--r-- 1 derek derek 39936 Jan 23 2007 redhat_sole_source_2007.doc<br />
</pre><br />
I will remove it from the current file system.<br />
<pre><br />
[derek@novelty quotes]$ rm redhat_sole_source_2007.doc <br />
</pre><br />
As you can see it no longer is there.<br />
<pre><br />
[derek@novelty quotes]$ ls <br />
dlt_pdf_quote2007.pdf Quote_250530976.html Quote_367884529.html UMD_008.xls<br />
dlt_pdf_quote.pdf Quote_300086759.html redhat_solesource.pdf<br />
dlt_quote.pdf Quote_353511914.html soleSource2007.pdf<br />
dy1014.xls Quote_367512608.html soleSource.pdf<br />
</pre><br />
I am going to go into the last hourly snapshot '''hourly.0'''<br />
<pre><br />
[derek@novelty quotes]$ cd .snapshot/hourly.0<br />
</pre><br />
As you can see the quote is still here.<br />
<pre><br />
[derek@novelty hourly.0]$ ls<br />
dlt_pdf_quote2007.pdf Quote_300086759.html redhat_solesource.pdf<br />
dlt_pdf_quote.pdf Quote_353511914.html soleSource2007.pdf<br />
dlt_quote.pdf Quote_367512608.html soleSource.pdf<br />
dy1014.xls Quote_367884529.html UMD_008.xls<br />
Quote_250530976.html redhat_sole_source_2007.doc<br />
</pre><br />
I copy it back to the original directory.<br />
<pre><br />
[derek@novelty hourly.0]$ cp redhat_sole_source_2007.doc /nfshomes/derek/work/quotes/<br />
</pre><br />
Change back to the original directory.<br />
<pre><br />
[derek@novelty hourly.0]$ cd /nfshomes/derek/work/quotes/<br />
</pre><br />
And it is back.<br />
<pre><br />
[derek@novelty quotes]$ ls<br />
dlt_pdf_quote2007.pdf Quote_300086759.html redhat_solesource.pdf<br />
dlt_pdf_quote.pdf Quote_353511914.html soleSource2007.pdf<br />
dlt_quote.pdf Quote_367512608.html soleSource.pdf<br />
dy1014.xls Quote_367884529.html UMD_008.xls<br />
Quote_250530976.html redhat_sole_source_2007.doc<br />
</pre><br />
<br />
<br />
__NOTOC__</div>Dalarohttps://wiki.umiacs.umd.edu/umiacs/index.php?title=CoreServices&diff=2524CoreServices2009-04-17T18:59:56Z<p>Dalaro: sp.</p>
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<div>* [[Kerberos|Authentication (UMIACS KRB5/UNIX)]]<br />
<br />
* [[ActiveDirectory|Authentication (Active Directory/Windows)]]<br />
<br />
* [[EMail]]<br />
<br />
* [[Printing]]<br />
<br />
* [[MailingLists|Mailing Lists]]<br />
<br />
* [[OSSupport|Operating Systems Support]]<br />
<br />
* [[NAS|Network Attached Storage]]<br />
<br />
* [[Web|Web Services]]<br />
<br />
* [[FileTransferProtocol |File Transfer Protocol]]<br />
<br />
* [[Subversion|Revision Control (Subversion)]]<br />
<br />
* [[Programming|Programming Languages]]<br />
<br />
* [[Backups]]<br />
<br />
* [[VPN|Virtual Private Networking]]<br />
<br />
* [[WinXPRemoteAssist|Windows XP Remote Assistance]]<br />
<br />
* [[LocalDataStorage|Local Data Storage]]</div>Dalaro