Thanks to all who responded, particularly Ruben Cortegoso, Alan Davis, Joe
Fletcher, and Udo de Boer. The majority said that the extra expense wasn't
particularly worth it. Several expressed concern about the slowness of
backing up over a network, but some said they did just that with no
problem.
Here is a nice little summary by Alan Davis of the differences between
AdvFS backup and EVM backup:
There are huge differences between using ADVfs clones and HSG80 clones or
snapshots.
Keep in mind that an ADVfs clone is similar to an HSG80 snapshot, an HSG80
clone is similar to an LSM snapshot and has no ADVfs equivalent.
When you are using ADVfs clones (limit one active per domain) the backup
job
runs on the server that you are backing up or, if you are using samba or
nfs
to mount elsewhere, the server must serve every byte over the network
connection. In either case this can present a significant load on the
system
for the entire backup process as well as wasting tape because the network
can't keep the tape buffers full.
An HSG80 snapshot (one active per controller) the snapshot can be mounted
to
any node on the SAN that understands the filesystem type. This allows
primary server to continue with no significant additional load while
another
server does the backup. There is the possibility of I/O contention in a
high-traffic situation, but that is at the HSG not the primary server. The
ethernet never sees the additional load since it's carried on the SAN.
An HSG80 clone (limited only by storage and number of connections to the
HSG) completely offloads the I/O traffic during backup at the cost of an
upfront delay while the mirror synchronizes. The clone mechanism is also
limited in a RAID5 environment, it only works with RAID0, RAID1 or RAID0+1
units.
Thanks again, this is a fantastic list!
Kimberly
----- Forwarded by Kimberly H Agle/Clerk of Courts/Common Pleas Court on
08/10/01 02:17 PM -----
Kimberly H
Agle To: tru64-unix-managers_at_ornl.gov
cc:
08/03/01 Subject: Too Many Choices
03:06 PM
Admin wizards,
We are in the process of buying a GS80 server for a new system(Oracle
database) on an RA-8000 SAN. I am still working on the backup strategy,
but here is a thumbnail sketch. We have one DLT891 tape library to back up
all our servers, both Unix and Windows. I plan to hook up the tape library
to a Windows machine, use Samba to map the Windows machine to the Unix
server, use the AdvFs utilities to take a snapshot of the database for
backups, then use ArcServe to back up the snapshot to the tape library.
My question isn't about the backup plan, although I welcome any
suggestions. Compaq wants to sell us their SANworks Enterprise Volume
Manager software for the snapshots. Can anybody tell me the advantages, if
any, of purchasing the SANworks software in addition to the AdvFs
utilities? I hate to buy EVM if AdvFs can do the job just as well.
Thank you,
Kimberly Hondel Agle
kimberly_agle_at_fccourts.org
Received on Fri Aug 10 2001 - 18:23:37 NZST