Delta can reduce the
cost of confidence
ORBiTs newest Backup+ option takes 3000 partial
backups to new level
Review by Shawn Gordon
ORBiT has been around for
many years, selling high-speed and online backup for HP systems.
Ive used its software myself for over 10 years now. For the
last few years the company has been talking about a radical new
approach to backups on the HP 3000 called Delta backup, and I was
very excited to get my hands on it.
Delta backup takes the
concept of a partial backup to a new level. Instead of storing the
files that have been accessed since the last backup, it actually
stores the pieces of the files that have changed, not the entire
file. So in the case of a database, you could have a table with 20
million records in it but if you only add 10,000 a day, and
you do a Delta backup every day, then you will only store the 10,000
This new functionality is an
optional part of Backup+, so you can still do your online backups and
zero-downtime backups and all the other great tricks that are part of
Backup+. But Delta gives you a new weapon in your arsenal for
improving uptime on the HP 3000, a system that lives on its uptime
How does it work?
The focus of this review is
the Delta feature of Backup+, since that is the really new piece of
the product. Ill talk a bit about some of the other features,
but Delta is the neatest bit. It takes the concept of a partial
backup and makes it more granular: we are now talking about pages
within files that have been touched, instead of whole files.
The first time you do a
baseline backup for Delta it starts a file monitor that tracks the
changes to the fileset that was used for the baseline. This is
cumulative, so the pieces of files that were modified on Monday are
also on Wednesdays backup. This monitoring technology looked
similar to what is used in the products Online backup, at least
from what I could see. Because of this logging process, it means
there can be no more than five Delta or Online (cumulative) backups
going on at once.
Let me explain this a little
more, since it can be confusing at first. Because of the logging
that goes on, you could have done four different Delta baseline
stores, for example, @.@.PROD, @.@.AR, @.@.DEV, and @.@.QA. Once you
have done the baseline Delta backup, these logging processes stay
So say you want to go and do
an ONLINE backup of some other fileset. This would still be
acceptable, because you are now at the limit of five. But if you had
two tape drives, and tried to do two online stores at the same time,
this would exceed the threshold of available logging. To me this
seems like a pretty reasonable limit, just something youll need
Backup+ contains many
features to allow for high speed, online backup in addition to its
Delta backup option.. Options such as ONLINE and ZERODOWN let users
continue to work during a backup, and once the synchronization point
is reached, they will be suspended for a minute or so while the tape
Backup+ also has compression
options to improve your tape usage. But if your tape drive supports
hardware compression, you are better off using that, because it will
be faster, typically, than software compression. You dont want
to use both, because that will slow down a backup and probably make
it larger. The product offers a very robust file selection protocol
for STORE and RESTORE that allows you to use a wide variety of file
objects such as type and various dates to select files, rather like
Backup+ also offers
store-to-disk, a very cool option. I did a test storing a database
to disk, and it was so fast and so small that I thought there must be
a problem. I restored the database into another group, and it was
fine. If you have the disk space for it, the store-to-disk is a great
way to do your backup quickly, and then move the file off to
There is only one thing that
I dont like about the Backup+ store-to-disk feature. I found
the file type which it creates so bizarre that I couldnt use
any utility of recent vintage, like FTP, to move the file between
systems. ORBiT told me that you can transfer this disk to disk backup
to a target machine by using DSCOPY. But you need to do two of
copies of each backup, one to copy the directory of the file, and the
other to copy the data in the file. I would find this a very fast and
convenient feature to get a fileset onto a shadow machine if
there was a better way to transfer the files.
A couple of options you can
use are the Tape Manager and Librarian (TML) and Restore Wizard. TML
is a very full-featured tape library and management system that lets
you track everything, everywhere. It is extremely robust but
it has a pure command-line interface, which can make it a bit tedious
to use, since you need to learn the commands. I was hard-pressed to
find any features that TML was lacking, and overall it is well
One interesting part of TML
is the Restore Wizard. As designed, it can be given a specific
restore instruction and tell you exactly what tape or tapes to use.
Of course, it relies on the fact that you are properly labeling your
tapes as required there is no way around this; there has to be
some human intervention.
Virtually any type of storage
device is supported by Backup+, including auto-changers and such. You
can make even more frugal use of your tapes by using appended
backups, although this might become confusing unless you carefully
track what is where. There is a lot in Backup+, and while you can get
by with using just a few of its features, you should at least browse
what is available to see what else you might find useful.
One important note that
people always wonder about when using third-party backup products:
Backup+ uses the MPE STORE facility to put a small version of Backup+
at the front of a backup tape. This small version will restore
whatever is on that tape, so you will always be able to restore your
information without a problem.
Installation and Documentation
For the installation you
restore a single file, put the tape back online, run the program you
restored, answer a couple of questions. Then all the files are
restored, directory structure adjusted as required, and installation
programs are run.
I was rather disappointed
with the documentation. It tops out at a hefty 500 pages, and I found
a fair number of errors and duplicated information. Its not
really cohesive and for this new user, I found it very
daunting. I was also disappointed that it was only distributed as a
PDF file on the HP 3000. You can get a hard copy of the manual from
ORBiT , but this PDF format is the default.
The Test Drive
Well, the first thing to do
to test Delta is to get a baseline store of your fileset. For my
purposes I did an @.@.@ store of the whole system. On my box (a
Series 957) and tape drive it took 114 minutes to store 1.2Gb of
data. I then ran a process that touched most of the files on the
system but only updated a couple of datasets and flat files.
Then, to test Delta, I ran
the Delta backup specifying the prior baseline ID for the backup.
This time the backup took two minutes, and only stored those pieces
of the files I was concerned with.
During the process I
encountered an error message on a database that Delta tried to
backup. The database had worked fine before the backup. It turns out
that this was a bug in Backup+ that was fixed just a week before I
began to test the software. ORBiT said it had shipped a patch to fix
this DBQUIESCE error, I just didnt have it on my test system. I
had no idea what the error message meant, although support said they
could have explained it to me quickly. I think these error messages
need to be more easily understood, without calling support.
The next step is the Restore
process. Here is where I found the Delta backup process confusing,
and its a good thing that that it is integrated with TML. I
physically purged one of the dataset files that was modified between
the baseline store and the Delta store. Then I wanted to restore the
dataset file to its state after the Delta store, so this became a
two-stage process. First I had to restore the file from the baseline
store, then I had to take the tape with the Delta iteration that I
was interested in and restore the file again from that tape.
While this might sound like a
bit of extra work, just remember that you dont restore files
that often it is typically for emergency purposes. One thing
to keep in mind: the Delta backups are cumulative. They are much like
an MPE Store partial backup, its just that we are cumulatively
storing the pieces of the file. So if you have the need to get a file
from its state on the third Delta of a set, you only have to restore
the baseline and the third Delta. You dont have to restore the
first and second Deltas, which certainly reduces the confusion.
If you try to specify
BASELINE on a restore from a tape that is a DELTA, I found that
Backup+ told me very clearly that I had the wrong tape, and
instructed me to put in the right one.
The Delta feature of Backup+
is fascinating, important and unique technology for HP e3000
customers. People now have enormous disk farms that have to be backed
up, and systems require constant uptime. You can do things like buy a
backup-only system, shadow to it and just back it up but given
the large amounts of data involved at some shops, that still might
not be practical. Using something like the Delta feature in Backup+,
in conjunction with the products Online and Zero Downtime
options, can radically improve throughput in performance.
When using Delta, you will
still need to do a new baseline backup every week or so but it
does dramatically improve your overall system availability and reduce
your cost of ownership for backups. DLT tapes arent cheap, and
neither are people who have to sit around and change tapes. Reducing
all of that adds up over time.
While I wouldnt say
that the Delta option is something everyone needs, I can certainly
recommend the Backup+ product to anyone that is doing HP e3000
backups. Its certainly faster and more convenient than
MPEs Store. ORBiT has some of the brightest developers of any
company in the 3000 community, a fact that has always given me a high
confidence level in their software.