Re: Thoughts on VTL solutions

> But we are also thinking of doing
> this over a WAN at 200Mbs since the new Power infrastructure is in a
> different geo so this would save shipping the VTL. So time is now
> going to be relevant.

Well for 22TB My math says 305.6 hours at 200 Mbps if you can actually use all 200Mb for the entire time perfectly. Yep that's 12 1/2 days. And this is unlikely to be the case, expect 1/3 more at least.

But that may be irrelevant because how would you connect the FC across the WAN? You can do this yes but it requires quite specialized (read: "Expensive") equipment to do that and likely you wouldn't need it once the transfer was complete.

To get the data to move over IP you'd have to get the data into IBM i, then copy it to the remote IBM i and then resave it to the new VTL. It's just not likely the two VTLs will communicate directly with IP as they are different vendors. But we've already kicked that dead horse!!

- Larry "DrFranken" Bolhuis

www.Frankeni.com
www.iDevCloud.com - Personal Development IBM i timeshare service.
www.iInTheCloud.com - Commercial IBM i Cloud Hosting.

On 5/21/2020 4:26 PM, Laurence Chiu wrote:

On Wed, May 20, 2020 at 7:36 AM DrFranken <midrange@xxxxxxxxxxxx> wrote:

> And if the data in PT is deduped, then this will be maintained in the
> target VTL? DSI does support deduping but I don't know

> if the algorithms on PT and DSI are compatible

Short answer: "They aren't but you don't care." :-)

When you are reading from the source VTL it will re-constitute, or
assemble, everything needed to make IBM i think the entire tape is
there. It will feed that down the fiber channel port. Then the DUPTAP
process (DUPMEDBRM uses that) feeds that data over to the new DSI VTL.
It then does its own internal deduplication as it stores the data on its
disks.

As Jim mentioned if the two DSI VTLs are connected already then they can
replicate the tapes between them and that WILL be a deduplicated
replication.

Yes that is what a vendor told me. Connect their solution to the fibre
channel switch that the current PT unit is connected to (and hence to the
Power server). Either runs BRMS and do the DUPTAP thing or they have a tool
that does the same. It will read from the PT, the data will be
reconstituted from the backup and then deduped back into the new VTL.

Remember that the VTLs need to maintain the 'illusion' that the full
tape is always there! IBM i has no clue that duplicated data is stored
only once. SO IBM I gets full tapes and writes full tapes.

As to how long this will take, yeah 'some minutes' indeed. I can't
really even hazard a guess without knowing how many tape volumes, how
much is on them, how fast is the FC Interface in use, and what size DSI
unit you acquire. And even WITH all of that it would be at best, a Guess.

The vendor is offering to do this on prem so over FC it should be okay
(22TB of actual backups so not large). But we are also thinking of doing
this over a WAN at 200Mbs since the new Power infrastructure is in a
different geo so this would save shipping the VTL.So time is now going to
be relevant.

Thanks again. It's good to have vendor proposals independently confirmed.

- Larry "DrFranken" Bolhuis

www.Frankeni.com
www.iDevCloud.com - Personal Development IBM i timeshare service.
www.iInTheCloud.com - Commercial IBM i Cloud Hosting.