Clem Kruger said:
>Good day to you all,
Curtis said
>>Good day to you!
Hi Curtis,
>Those of you who are thinking of using VTL's I would urge to re think
>that technology.
>>Can't say I agree with you there. I hate responding in the negative,
but your message was so strongly worded against VTLs, I felt I just had
to respond.
I have nothing against VTL's or their manufacturers.
>There are so many issues,
>the main being you are still bound by SCSI rules.
>>You're bound by SCSI rules as long as you're using SCSI. Not sure
what you mean here.
The VTL follows the SCSI rules as far as their usage is concerned .Any
failures will be reported to the OS as SCSI errors. What I am saying is
we all would and should move away from tape. Should you loose
communication between your master and media servers, you can be left
with a tape stuck in the tape drive (VTL or NO) and cause issues with
your backups.
>Another fact is that you need to delete tapes that have
>been expired to claim back the "Disk" space.
>>...or you expire the tapes just like you do in a real tape library.
But, again, this makes perfect sense.
Look at this again, an expired tape (say 200GB) will still use 200GB of
unused space until you delete and recreate the tape again. When you have
databases in excess of 5TB, the wasted space can become rather
expensive.
>Have you heard of poor media on VTL? Yes you get it and it is serious.
>>Then you had a BAD VTL! I have heard of some bugs from some early
implementations, but I haven't heard of anything recent. If you're
getting a "bad >>tape" in a VTL, then something is seriously wrong. And
I would get a VTL manufacturer to have something in writing to deal with
this thing that should >>never happen.
Poor media could be caused by communication loss, the same as in real
tapes (you are emulating tape).
>As far as backing up to VTL and then to tape,
>it is best to do an in-line backup,
>where you backup to both VTL and real tape at the same time.
>>To use your terminology, this method causes you to be bound by the
rules of tape. Your backup will now be forced to go the speed of the
lowest common >>denominator, the tape drive.
Yes, it is about 35% slower, but you use this for your weekly and
monthly schedules. The VTL's rule for a week or two the real tapes carry
the real retention period of the policy. If you use Vaulting in
conjunction with this method, the real tapes can be ejected along with a
catalogue for those tapes making an offsite recovery simple. You can
imagine what you VTL costs would be if you are backing up many databases
in excess of 5TB's.
>NetBackup has released their Disk to Disk API to the public Domain
>and we will soon be out of this interim phase of VTL's.
>>The companies that will program to that API are the very companies
you're recommending not using. With Data Domain as the only exception,
all of the >>companies that are programming to that API are VTLs.
Here I disagree with you. The released API is for Disk to Disk not VTL.
Symantec have said they would continue to support VTL. VERITAS 6 and 6.5
both support disk to disk backups, which is a world apart from disk to
VTL. You can backup to ANY disk on your SAN.
My personal choice is using Storage Foundation to create SNAPSHOTS on
the SAN (free of any hardware constraints) and then backup or replicate
the snapshot to your offsite storage site or DR site or backup the
snapshot to tear 4 storage. Remember we all should be moving toward a
faster method of RECOVERY either at your DR site or production site.
Storage Foundation Snapshot technology means instant recovery.
>I am current investigating DataDomain which works extremely
>well with NetBackup. I find the amount of space being saved
>is quite phenomenal. The speed of backups is exceptional.
>>And almost all VTLs now offer this functionality as well. DD's been
in the industry longer than everyone else in this space and their number
of de-dupe >>customers is miles ahead of anybody else. I'm not saying
anything's wrong with them, but it sounds like you're saying "VTLs are
dead, long live Data >>Domain." Don't think I'd go that far.
No Curtis, I am not saying VTL's are dead not by a long shot, what I am
saying is look at what comes with your backup application. D2D is
already included in the package (from most backup vendors), rather use
that. If you have huge amounts of data, look at Storage Foundation. If
you want to avoid backing up the 80% of the same files on all you
similar operating systems don't purchase an EMC Centera or similar DISK
Hardware technology, (where you will be locked into that technology),
rather look within the NetBackup stable and do this while you are doing
your backups. Pure Disk will do that for you.
>There is also a wonderful replication facility which guarantees
>your data to you off sire storage in no time at all.
>>Again, they're an early mover here, but this is starting to become
commonplace.
My discussion here was for those who do not want to use Storage
Foundation. The method used by DataDomain and their de-duping is unique
and fits in well with NetBackup and the other backup products.
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