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Aux Copy to Tape Properties (Read 3862 times)
03. Oct 2011 at 11:13

russ_comm   Offline
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Commvault Support
Venice, FL

Posts: 40
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Good Morning,

I am trying to chase down why I keep having the issue of there being multiple tapes consumed from our scratch pool in our tape library when our Aux copy to tape jobs run. I have tried different configurations of the Aux copys properties under the media tab with no success. Right now, they are as follows:

Optimize Media Usage
[x] Combine source data streams to [2] Streams(s)
     [x] Multiplex source streams
     Multiplexing Factor: [4]
[x] Write to a different library compared to source copy
Erase Media
     [  ] mark Media to be Erased After Recycling

And I am going to try changing them to this:

Optimize Media Usage
[x] Combine source data streams to [1] Streams(s)
     [x] Multiplex source streams
     Multiplexing Factor: [5]
[x] Write to a different library compared to source copy
Erase Media
     [x] mark Media to be Erased After Recycling

Any light that can be shed on this issue would be awesome. I am trying to grasp how this whole writing to tape function works within CommVault. It is seemingly not straight forward and why the CommVault will not append one aux job after another to tape regardless of the storage policy is beyond me. By looking at these settings and after marking them what I thought was correct, it is still an issue and we now have 2 different tapes looking exactly the same for 1 storage policy. I was advised to set this to [2] Streams(s) by Dell support on the account of us having 2 tape drives in our library, but now we are eating up 2x $100 tapes for just 90GB of data when I have terabytes worth of data needing to be backed up to tape with no place to go!
Thanks again for any information on this seemingly bewildering issue that is no problem in our other solution Backup Exec 12.

Russ
 
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Reply #1 - 04. Oct 2011 at 01:13

-=PsY=-   Offline
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Commvault User

Posts: 405
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Just some quick info to hopefully point you in the right direction.

Firstly, you can't really mix data from different Storage Policies / Copies within the same tape. It would defeat the purpose of having Storage Policies if you could.

Subsequent Auxiliary Copies will append to the same media, as long as you don't have any options enabled to prevent it. For example, the "Start New Media", and "Mark Media Full On Success" options.

You can find these options within the jobs schedule properties (assuming you're using Schedule Policies):

CommCell > Policies > Scheduled Policies right click on the appropriate Auxliary Copy Schedule Policy, press Edit
At the <schedule policy name> dialog, select the appropriate Schedule from the Tasks section, press Edit
At the AuxCopy Options dialog, browse to the General tab.

Within that General tab, you will also notice the Number Of Readers option.

If you have multiple streams configured here, as well as either the "Start New Media" or "Mark Media Full..." options, there is the potential of "tape wastage"

For example, let's say that an Auxiliary Copy only has two 50GB streams and the "Mark Media Full" option enabled, each stream will get its own tape, and will be marked full on completion. Subsequent Auxiliary Copies will not be able to use this tape.

(apologies for the quick post, only have limited access to a computer over the next week)
 
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Reply #2 - 04. Oct 2011 at 07:12

russ_comm   Offline
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Commvault Support
Venice, FL

Posts: 40
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Thanks a bunch for your response PsY!

Regardless of being quick and brief, it definitely revealed yet another area for options to be configured. I really am see no way around this as of yet.

My boss was sold on the fact that all jobs can be written to tape sequentially, one after another. Whether or not the sales rep thoroughly understood the CommVault system and that having different storage policies for all of our different systems would result in for tape consumption is something that I am unsure of. The rep may have seen an opportunity to not only sell some hardware and software, but also a bunch of renewable licensing for different types of media agents. We already have had a licensing issue with us being sold licensing and not having the license file being correctly configured. On top of resolving this, I am also in charge of straightening out our setup and configuration.

I think that part of the alarming difference is that we went from having anywhere from 3-5 tapes sent off-site to having double or triple that every week. If we have to buy more tapes and do this the only real way you can do it correctly, then fine. I have tried creating an aux copy to tape policy and applied it to all of our clients and we are still getting the tapes pulled out of the scratch pool and given labels associated to the specific storage policies. Until I do the training at the end of the month, I will be struggling through this on my own.  Having the help of this board is huge and Im glad to have found it!

Russ
 
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Reply #3 - 06. Oct 2011 at 08:03

-=PsY=-   Offline
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russ_comm wrote on 04. Oct 2011 at 07:12:
...having different storage policies for all of our different systems...


How many Storage Policies do you have?
 
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Reply #4 - 13. Oct 2011 at 09:32

russ_comm   Offline
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Commvault Support
Venice, FL

Posts: 40
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Well, as it is configured now, we have a total of 7 storage policies. As I read more into the books that I have, I'm thinking that I want to bring this down to 1 storage policy for all of our production servers and have the CommVault have 2 streams availble for auxcopy to tape in parallel since we have 2 LTO-5 Ultrium drives in our library. I believe that if I reconfigure our storage policies and start there first, this will all make better sense to me. On a side note, I did get approval for going to the CommVault training in Orland at the end of the month from 10/31 through 11/04 in Orlando, FL. Hope to see someone from here over there!
 
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Reply #5 - 17. Oct 2011 at 07:27

-=PsY=-   Offline
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It is a bit of a balancing act, and I think you will find that you still need to have more than a single Storage Policy.

Just a super quick example:

In my environment, the vast majority of Restore Requests come from end users who have "lost" files/emails, usually at some point over the past month. With that in mind, I simply have a deduplicated Storage Policy specifically for this type of data, which is retain within the Primary Copy (MagLib) for ~30 days.

This means that the bulk of my restores are from the MagLib (which is significantly quicker than restoring from tape), and also means that I don't have to leave my chair as often to juggle tapes!


On the other hand I also backup a stack of system data, corporate applications, databases, and all kinds of other stuff that I rarely have to restore. For this data, I don't need to retain it on costly MagLib to allow for quicker restoration, so I've setup another Storage Policy (not deduplicated), which is set to only retain the data within the Primary Copy (again, MagLib) until it has been Auxiliary Copied to tape (this is referred to as a Spool Copy)


Now, if I was to only have a single Storage Policy, I wouldn't have the flexibility that I have now without the needing significantly more MagLib capacity. So, whilst having a single Storage Policy may save you on tapes, it may cost you flexibility, or atleast additional MagLib capacity.
 
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