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migrating DV* files to cheaper storage

Created: 26 Feb 2013 • Updated: 01 Apr 2013 | 7 comments
KeirL's picture
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Is collection and migrations the only\best way to move files to cheaper storage?

I want to create a tiered storage layer whereby archived email messages that are over 2 years old are moved to EV secondary (slower) storage as opposed to the faster storage where the more recently archived items reside.  Is the only way to do this by first collecting the files into CAB files and then migrating to the new location?

I assume I just can't migrate without running a collection first? As I'm doing this to benefit from a cheaper storage tier and not to improve backup speeds  I don't really need the cabinet files created just need to migrate the files as they are - hope that makes sense

What is the recommended size of the cab files and what is the downside to increasing the size from the default 10MB.... My main concern is that I don't want to have a user experience of over 1 min in opening an item that is in been migrated and I'm not too sure on what the process that EV needs to go through to recall an item.... does it just extract the required item or does the entire cabinet file get restored back to the vault store partition? - hence why 10MB files are the default to minimise the delays to the user.

Many Thanks as always

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TonySterling's picture

Yes, you would have to enable collections before you can migrate. 

I recommend you give this a good read:

It is pretty much all you wanted to know about collections but didn't know to ask.  :)

KeirL's picture

Thanks Tony

I think that's helped me a lot. So is the fact that the cab files are only 10MB by default as opposed to 100MB (which would be better still for backup performance) due to getting a balance between increased backup performance and time it takes to restore an item?

I'd like to make these cab files as big as I can whilst still retaining a user delay of less than 1min.... is there a rule of thumb (or do you have any real world experience) on how long it takes a cab file to recall an email message?

AndrewB's picture

just out of curiosity, what's your current EV storage and what are you planning to use for the second tier? in theory, your vault store partitions sit on cheap low tier storage to begin with.

Andy Becker | Authorized Symantec Consultant | Trace3 | Symantec National Partner |

John Santana's picture

Maybe KeirL is using some other data deduplication store or NAS with cheaper SATA hard drive ?

Kind regards,

John Santana
IT Professional


Please be nice to me as I'm newbie in this forum.

KeirL's picture

Hi Andrew\John

current EV storage is on a  P2000 SAN which was left over when we moved to 3Par. The P2000 itself has both FC and SATA drives and this is where I was going to have the two tier EV storage. Initially onto the fast drives and then migrated to the SATA drives after a couple of years. But there is still a need to recall itmes that may be several years old and I didn't want to go down the collection and migration route if it was going to introduce length recall times as it's not easy to back out.

I was hoping to get some feedback on people who may already use collections and migrations to understand real world experiences with this.

Something like: "we use 100MB cab files on old storage that delivers 500iops and recall time is about 20 secs" would be great info for me :o)

Cheers K

John Santana's picture


That does make sense.

At the moment I'd also like to implement storage tiering but in this case it is with EMC Data Domain for the old EV items (Exchange Emails and File servers).

Kind regards,

John Santana
IT Professional


Please be nice to me as I'm newbie in this forum.

Rob.Wilcox's picture

Personally if I went for migration to third tier storage, I'd go for CABs of 20-50 Mb.  It does sort of depend whether the contents of the CABs is going to relate to FSA data, or Exchange data.  FSA data tends to be larger files, than emails.

It also depends how 'close' to the EV server this storage is.  All on the same highspeed LAN and just a bunch of home-grown disks is going to be able to serve up content pretty quickly.

Finally it does depend on how old the data is before you migrate it away... and how likely it is that it will be recalled, eg Discovery Accelerator searches, index rebuilds and so on.