I covered this quite a bit in a blog entry a while back:
http://www.backupcentral.com/content/view/41/47/
Curtis Preston | VP Data Protection
GlassHouse Technologies, Inc.
T: +1 760 710 2004 | C: +1 760 419 5838 | F: F: +1 760 710 2009
cpreston AT glasshouse DOT com | www.glasshouse.com
Infrastructure :: Optimized
-----Original Message-----
From: EMC NetWorker discussion [mailto:NETWORKER AT LISTSERV.TEMPLE DOT EDU] On
Behalf Of Mitko Stoyanov
Sent: Wednesday, August 06, 2008 10:11 PM
To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Subject: [Networker] Networker D2D2T backups and D2T cloning speed
Hi,
I'm in a process of evaluating a D2D2T backup architecture which uses
LTO4 as tape technology, and adv_file devices for the D2D part. The
outcomes are to get faster recovery (via the D2D part), and speed up the
backup of many slow smaller clients via backing first to disk, then
cloning to tape (the current network infrastructure can't drive LTO4
drives fast enough).
Everything is going up to the expectations so far, except the
cloning....from my research so far it looks like the D2T cloning is done
as single-threaded job, with one saveset cloning at a time.
That would be OK with large savesets (some are > 100GB) , but an
incremental backup of a small Unix OS file system may produce a saveset
only a few Kbytes. Such small savesets can't produce the steady data
stream required for the LTO4 devices (shining their shoes...).
Hopefully somebody here could answer some of these questions:
* When Networker clones from adv_file device to tape, is the adv_file
saveset copied as it is without looking inside what is saved, or is
"restored" internally and then backed up as a saveset to the clone tape?
* Is there any workaround for the single-threaded saveset cloning? Any
plans to multiplex the adv_file savesets when cloning to tape? That
looks to me as a major showstopper when using faster tape technologies
to clone D2D backups, as eventually these backups have to go offsite,
and the vast majority of clients use tapes for that..
Regards,
--ms
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