Ottawa PC Users' Group, Inc.
Open File Manager
Software Review by
If you are responsible for data recovery on a computer
system, don't skip this article. It just might save your
Did you know that your backups may be worthless? It
surprised me to discover this fact. If you are running a
24x7 operation, you have to run your backups while people
are using the system. This can put your data at risk. The
problem stems from files that are open when the backup is
There are three ways backup programs typically handle
- First, they simply skip the open file. NTBackup (the
program that ships with NT) will dutifully add an
entry to the log file (You do read the log files,
right?) saying that it encountered an open file
and skipped it.
- They may force a write to tape. Most third party
backup software can do this and lull you into
thinking your data is OK.
- Use a special purpose extension that handles a
particular data type (for example, Exchange
Server and SQL Server) to backup the data.
If you skip open files, providing you review your
logs, at least you know what you are missing. In many
cases, you can take steps to ensure a valid backup of the
files. For example, at my office we have users' personal
address books on a LAN drive. NTBackup will not backup
these files if the person neglected to close Exchange
before going home or if someone logged on from home while
the backup is running. One solution: force everyone off
the network while the backup runs. However, try to
convince a couple of thousand users that the reason they
can't use the network from midnight to 2:00 a.m. is for
their own good!
If you force a write to tape, much of the time, you
will be OK. In the example above of personal address
books, it will usually work well. Although the personal
address books on our network are open these files do not
experience a lot of write activity. There is a not-so-special
case that it won't work. Consider a large database file
with active transactions happening while the backup is
running. If you force the backup program to backup that
file, it will be backing up part of the file while other
parts are undergoing rewrites. As the backup proceeds to
later parts of the file, the earlier sections (already
backed up to tape) may experience rewrites. In any case,
your backup does not reflect the most current file data.
If you ever have to restore this file, it may effectively
be junk although you may not know it until it is too late.
The third method, using a special extension to your
backup software, is safe. These solutions are costly and
typically very narrow in focus. You may need to purchase
multiple extensions to handle all your file types or you
may not find an extension for the file type you are using.
I recommend that you investigate a fourth solution-Open
File Manager (OFM) version 5.1 from St. Bernard Software.
It eliminates the problems in an elegant and powerful
manner. It allows you to backup safely any files and
works with most backup programs: OFM currently supports
21 programs from 16 vendors. The concept is simple. When
it finds an open file, it begins keeping track of changes
to that file. Changes are written immediately to disk;
your data is not at risk. While allowing the disk write
to take place, it keeps track of the data that used to be
there and puts it in a pre-write cache file. When the
backup program tries to backup that portion of the file,
OFM substitutes the data in the pre-write cache. You end
up with a faithful copy of the file as it existed at the
beginning of the backup operation. For cases requiring
sets of files that must synchronize at a consistent
stage, such as a database file and its indexes, OFM can
handle the entire file system as a single entity. The
entire file system backup will faithfully reproduce the
data as it existed at the start of the backup.
The pre-write cache can be configured to retain its
contents until the backup software performs its verify
phase. If disk space is limited, you can configure OFM to
release the pre-write cache data as soon as each
individual file is written. Other configuration options
allow you to eliminate special handling of specific files
or directories (such as the paging file or the TEMP
directory) and to specify the location of the preview
cache file. If you have multiple backup systems in your
organization, you can manage OFM on all systems from a
A handy agent included with OFM allows you to
configure an account to copy open files using the same
technology. Numerous times I have tried the impossible:
to access an open file on our network. OFM would have
saved me running around getting users to close the file.
This agent will act only over the network; users with a
single, stand-alone machine can't benefit from this agent.
OFM runs as a service under Windows NT 4 (Workstation
or Server) or as an NLM under Novell Netware. The memory
footprint under NT is around 1MB.
I tested OFM on PUB II-the NT Workstation that runs
our new BBS. The BBS software keeps about 50 files open (databases
for messages, user accounts, indexes, etc.) whenever the
BBS is running. OFM handled all these files perfectly and
allowed NTBackup to perform a complete and accurate
OFM is definitely not for every situation. You must
evaluate your own backup strategies; if they are
adequate, do not spend more money. Perhaps you can modify
your existing procedures to compensate for any
deficiencies. Finally, you may decide to live with any
data losses that occur. Please- if you choose this last
course of action, consider carefully the risks to your
company's bottom line and your own pay cheque. Don't tell
OFM manager is not cheap. Single copies for NT Server
are US$575.00. Quantity discounts are available; the
smallest for NT Workstation is a 5-pack at US$495.00.
St. Bernard Software currently has a promotion: any
organization can request a free, full-function copy of
the version for NT Workstation. I have requested a copy
to use for OPCUG. St. Bernard is also offering a discount
to OPCUG members. Contact Tod Helmink at 1-800-782-3762
and be certain to mention your club membership. A 15-day
trial version is available from the company's website: http://www.stbernard.com.
Proprietary package from St.
US$575.00 (Single copy for NT Server)
Web site: http://www.stbernard.com
Copyright and Usage
Computer Users' Group (OPCUG), Inc.
3 Thatcher Street,
Ottawa, ON K2G 1S6
The opinions expressed
in these reviews may not necessarily
represent the views of the OPCUG or its members.
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Page created: 14-Jun-98