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Synthetic Full vs. Regular Full

Posted by aa7ae 
Synthetic Full vs. Regular Full
February 17, 2007 10:43AM
I'm using Commvault over to some Data Domain restorers as my backup infrastructure. I do incremental backups everyday and regular full backups starting Friday night. Regular full backups are brutal and is taking well into Saturday before they finish. Something on the order or 10TB of data to backup with over 100 windows servers. Several people I talked to didn't recommend I use synthetic full backups with this arrangement because of the high load it would present to the Data Domain devices to reconstruct all of the incremental backups to a synthetic full. My question would be this. Even if running synthetic full backups would cause a high load on the Data Domain devices, wouldn't that be better than the high load I'm putting on my production servers well into the next day moving useless duplicate data? Why not take the lesser of two evils?
Synthetic Full vs. Regular Full
February 18, 2007 04:28PM
I think synthetic full backups are a great thing, and allow you to
create a real full backup without getting the data from the client. As
to whether or not they will have a place a big load on your data domain
boxes... As long as it doesn't slow down your regular backups, who
cares?

And that's not likely to happen if you spread the synthetic fulls out
across the week/month and make them when the LAN backups aren't running.
(Remember that since they're not impacting your LAN or clients, they can
run any time.) So every night, perform an incremental on everything.
Once they're all done, then perform a synthetic full on 1/7th of your
entire environment (if you're doing weekly fulls) or 1/28th of your
entire environment (if you're doing monthly fulls).

I'd say try it and see what happens.

---
W. Curtis Preston
Author of O'Reilly's Backup & Recovery and Using SANs and NAS
VP Data Protection
GlassHouse Technologies

-----Original Message-----
From: backups-bounces < at > backupcentral.com
[mailto] On Behalf Of aa7ae
Sent: Saturday, February 17, 2007 10:44 AM
To: backups < at > backupcentral.com
Subject: [Backups] Synthetic Full vs. Regular Full

I'm using Commvault over to some Data Domain restorers as my backup
infrastructure. I do incremental backups everyday and regular full
backups starting Friday night. Regular full backups are brutal and is
taking well into Saturday before they finish. Something on the order or
10TB of data to backup with over 100 windows servers. Several people I
talked to didn't recommend I use synthetic full backups with this
arrangement because of the high load it would present to the Data Domain
devices to reconstruct all of the incremental backups to a synthetic
full. My question would be this. Even if running synthetic full
backups would cause a high load on the Data Domain devices, wouldn't
that be better than the high load I'm putting on my production servers
well into the next day moving useless duplicate data? Why not take the
lesser of two evils?

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_______________________________________________
Backups mailing list
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http://backupcentral.com/mailman/listinfo/backups_backupcentral.com
Synthetic Full vs. Regular Full
February 18, 2007 05:40PM
I'm going to change my whole backup schedule in Commvault to use synthetic full's this week and I'll report on how different the results are. Thanks for your input.
Synthetic Full vs. Regular Full
February 23, 2007 12:51PM
One of the Commvault support techs I just spoke with didn't like Synthetic fulls in his last job because he didn't feel they're as accurate as a real full backup. How could this be true? I'm I somehow assuming some kind of hidden risk using synthetic full?
Synthetic Full vs. Regular Full
February 23, 2007 01:26PM
If they're done correctly, they're the same as real fulls. You should
test how "real" they are. If the resulting tape has the same files that
a full backup would have, there's no effective difference.

The only difference is that the files will be laid out on tape in the
order they were backed up, not in inode/filesystem order. I don't see
that as being anything to worry about. If you're restoring the whole
filesystem anyway, they'll all get restored.

---
W. Curtis Preston
Author of O'Reilly's Backup & Recovery and Using SANs and NAS
VP Data Protection
GlassHouse Technologies

-----Original Message-----
From: backups-bounces < at > backupcentral.com
[mailto] On Behalf Of aa7ae
Sent: Friday, February 23, 2007 12:52 PM
To: backups < at > backupcentral.com
Subject: [Backups] Re: Synthetic Full vs. Regular Full

One of the Commvault support techs I just spoke with didn't like
Synthetic fulls in his last job because he didn't feel they're as
accurate as a real full backup. How could this be true? I'm I somehow
assuming some kind of hidden risk using synthetic full?

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