There's a lot of past discussion of the pros and (predominantly) cons of
turning on the NetWorker client compression directives when your tape devices
that do their own compression. But what about adv_file devices?
It looks like a multiple win. I probably speed up network I/O a little bit. I
probably speed up writes to the adv_file volumes on my storage node. I probably
extend the lifetime of my tier3/10TB Disk Option license -- upgrading to
tier4/50TB would cost me $20K plus support (is this true? never having actually
exceeded my licensed disk backup option limit, though i'm starting to get
close, how exactly does NetWorker verify compliance?). I probably slow down
clones from disk to tape somewhat, but it looks like I am still able to feed my
new LTO-4 drives at 80+ MBps without shoe-shining.
Background: Our 7.2->7.4.2 Upgrade Success Story
================================================
Old system
----------
NetWorker 7.2.2 on RHEL 3 32-bit. Backups went to Apple XServe RAIDs (best
price/gigabyte for FC-to-SATA storage 2 years ago; this has since changed) at a
DR site on the other end of a 5km LH fibre channel link, and were then cloned
back to an Overland NEO library with 4 SDLT-320 drives.
Pressure to upgrade
-------------------
The 49 tapes in the SDLT-320 library were only enough for about 7 days' worth
of backups. Frequent swapping of tapes was tedious and error-prone. As much as
I was offended by the elimination of nwadmin and introduction of Java GUI, it
was time for RHEL3 and NetWorker 7.2.2 to go.
New system
----------
NetWorker 7.4.2 32-bit version (not 64-bit, due to NetWorker issue LGTsc06585)
on RHEL 5.2 64-bit. SELinux is enabled, with the default targeted policy in
Enforcing mode -- no issues thus far. It is also running a Xen kernel, with
NetWorker in the master Dom0 -- no issues thus far. My NetWorker server can
host Xen guests in a DR situation, or possibly (with live DomU migration)
during the normal business day, when the system is otherwise idle. Same
strategy of primary backups to remote XServe RAIDs with cloning to a tape
library elsewhere, but the tape library is now a Dell TL4000 with 2 FC-attached
LTO-4 drives. I bought FC rather than SAS because it saved me a PCIe slot
(dual-port HBA, one port connects to disks and one port connects to tapes) and
allows me to locate the tape library more than 4m away. Although LTO-3 would
have met our needs for at least three years, I bought LTO-4 because the cost
differential wasn't that great and (unlike the case with SDLT) I have heard!
from multiple sources that LTO-4 can speed-match just as slow as LTO-3, so
why not.
--
Rich Graves http://claimid.com/rcgraves
Carleton.edu Sr UNIX and Security Admin
CMC135: 507-646-7079 Cell: 952-292-6529
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