VTL vs. Backup to Disk

I'm trying to figure out the pros and cons for backing up to a disk
device vs. using a virtual tape library like the Clariion Disk Library.
You're backing up to disk on both of them, presumably at the same
speeds but it seems that the VTL adds a level of complexity and cost.
Does anyone have any experience or opinions of either two?

Brian

On 14 Jul 2005 07:01:38 -0700, "
wrote:

I'm trying to figure out the pros and cons for backing up to a disk
device vs. using a virtual tape library like the Clariion Disk Library.
You're backing up to disk on both of them, presumably at the same
speeds but it seems that the VTL adds a level of complexity and cost.
Does anyone have any experience or opinions of either two?

Brian


In theory the VTL will be faster. True, both are disk based but there
are optimizations on the raw device and firmware/software for VTL's.

Whether or not you would actually see a performance difference is
questionable, but that's the theory.

~F

Faeandar writes:

Whether or not you would actually see a performance difference is
questionable, but that's the theory.

To the OP,

Perhaps you can see if you can get a loaner unit for a couple of weeks
and run some benchmarks / tests?

Please let us know what you decide, and the reasons.

--
David Magda dmagda at ee.ryerson.ca
Because the innovator has for enemies all those who have done well under
the old conditions, and lukewarm defenders in those who may do well
under the new. -- Niccolo Machiavelli, _The Prince_, Chapter VI

What backup software are you using? It really depends on that and how
it supports disk versus a library. Most solutions support libraries
allot better then disk. So the VTL will offer more functionality then
the disk solution.

I'm using both Legato NetWorker and Veritas NetBackup in different
environments. I should expect that there wouldn't be much of a
difference in performance between the two.

I would say use a VTL solution. This way it can be shared between the
two applications. The CDL soltuion from EMC is really using falcon
store software. It works well and will allow Net Backup and Networker
to use the same space. If you go with disk you are limited to one host
owning the lun and only that host can dump data on it. The VTL will
make it allot easier to manage.

What other considerations might there be. The two environments I'm
speaking of would have their own dedicated disk/VTL and sharing
wouldn't be a issue. What about cost, performance or functionality?

On 14 Jul 2005 07:01:38 -0700, "
wrote:

I'm trying to figure out the pros and cons for backing up to a disk
device vs. using a virtual tape library like the Clariion Disk Library.
You're backing up to disk on both of them, presumably at the same
speeds but it seems that the VTL adds a level of complexity and cost.
Does anyone have any experience or opinions of either two?

Brian


Something to consider....

http://searchstorage.techtarget.com/...&ad=523069USCA

~F

Backup to disk and then what? Offload to Tape?
Look our solution for Windows server backup from http://www.datamills.com I cut and paste a testimonial.

"Having been let down by our old tape-based backup system once to many times I searched the internet high and low for an alternative solution. I knew that the logical route would be a disk-to-disk backup between the server and a remote machine, but I was concerned that transferring so much data across the network would cause a significant drop in performance.

Over the period of several months I downloaded and tested dozens and dozens of different backup systems, but none of them really did what I wanted; store multiple versions of the data from days, weeks & months ago without needing to multiply the disk space (and cost) it required! I was almost ready to give up when I stumbled across DataMills Relative Rev Backup.

At last I had found an application that would store incremental backups as if they were full backups... what they are in fact is virtual backups! Genius!

I now backup all my data in less than 6 minutes, and can restore any version of any file from an archive of backups that goes back months. It is so easy and so reliable I can forget about it and get on with more important things.

Thanks DataMills!" -- David Hasell, Croydon, UK





wrote in message oups.com...
I'm trying to figure out the pros and cons for backing up to a disk
device vs. using a virtual tape library like the Clariion Disk Library.
You're backing up to disk on both of them, presumably at the same
speeds but it seems that the VTL adds a level of complexity and cost.
Does anyone have any experience or opinions of either two?

Brian

Brian,
Here is some stuff I did when I was an analyst w/ ESG. It talks a
little bit about the difference.

Also, it may add a little on the cost, but on the complexity side,
after setup (configuring the thing to look like the tape library you
want) it is very simple to deploy, manage and recover.

The cost may be up there w/ things from EMC or NTAP but there are some
good prodcuts available from a number of different vendors that are
less.

here are some of my writings

Does Disk Solve The Problem?
Based on our last comments about integrated disk and tape solutions,
and all the hype disk based backup solutions are getting these days,
lets take a closer look at how disk based solutions are helping the
data protection paradigm evolve. There has been a lot of talk
concerning how the backup paradigm will change toward disk-based
solutions. The latest and most common discussion is about how
disk-based technologies will be used to increase data recovery. As ATA
arrays are becoming more mainstream and commoditized, the cost per MB
of low-end disk arrays are beginning to converge with tape costs. As
this convergence happens, IT managers are starting to discuss the
cost-related pros and cons of managing their existing backup processes
versus the ease of data management and higher availability that
disk-based backup solutions provide. Again, most of these discussions
revolve around disk and disk-based appliances.

Traditional Backup/Recovery Technologies - Most of the traditional
software backup vendors (BakBone, CA, CommVault, HP, Legato, SyncSort,
Tivoli, and Veritas) have stated that they do or will support backup to
disk. This means that IT can now purchase one of the many new ATA
arrays to be used for caching their tape libraries. Moving data to
disk with a traditional backup product is still backup in its purest
form. The faster speed of disk has helped with shrinking backup
windows, but only slightly.

To the credit of the traditional backup vendors is that they are
continuing to innovate. Companies such as Veritas are adding the
capability to do synthetic full backups. This helps alleviate the need
for full backups. BakBone continues to innovate as it pertains to
networked storage backup, also a good platform for increasing backup
performance.

Data growth is still outpacing this backup window, which leads us back
to the theme of this brief, which is, "How will data protection
evolve to meet these challenges?"

Virtual Tape Libraries (VTL) - Over the past 18 months, we have seen
more and more intelligence move from the backup software into either
the fabric or the arrays being used for backup/recovery. Recently,
there has been a spate of VTL announcements. VTL software is designed
to make a disk array look like a tape library. Vendors who deliver such
technology include Alacritus, Diligent, Falconstor, IBM, Quantum,
Sepaton, and even BakBone (which has designed VTL capabilities into its
software). Some of these companies deliver software while others
deliver appliances with software built in, such as the Quantum DX30.
The goal with VTL is to get IT past the psychological inertia
associated with migrating from disk- to tape-based backup. VTLs fit
seamlessly into the existing backup environment and require very little
or no change to the existing processes. The only change in the backup
process is for IT to redirect the backup application to the IP address
of the array instead of the tape library, and backups should be ready
to run. The data written to disk is exactly what you would expect to
see on tape, and can be easily cloned or moved quickly to tape without
affecting media management schemas - which is crucial when it comes to
recovery.

Disk Backup/Recovery Targets - As we move along the data protection
continuum, there are a couple of diverging schools of thought on
disk-based backup and recovery. In the first camp is the group of
people who believe in disk-based backup as cache and don't understand
the need to put the data on disk in a format that is like tape. Their
view is, "What is the point? VTL software costs more money and at
the end of the day, IT must have a process of moving the same volume of
data off to tape for archival." However, depending on the backup
software, cloning data to tape may not be possible when VTL is not
used. For example, data written to a 120GB disk drive with backup
software cannot be cloned to 60GB tapes. Trying it could also cause an
issue with the media management schemas.

This is where the conflict between existing processes and new processes
comes into play. While some IT folks attempt to mirror existing
processes, others only care that their primary storage is always
available, and they don't care that it may take all day to move backups
from the ATA array to tape. That said, most disk vendors' products
can act as a target for backup, these vendors include Iomega, Network
Appliance, NexSAN, and Snap as well as many others.

The other disk-based school of thought deals with recovery. This is
not to say that by putting data on disk, you don't increase recovery
speed, it does, but IT still needs to use the processes defined by
traditional backup software to recover data. Even though recovery
focused technologies may not meet all backup requirements, they can
help companies move up the data protection index by promising faster
backup and more importantly, a greater chance of data recovery.