Backup and Tape device answers

[Tim Jones]

Hi Folks,

I've been working with and designing backup tape hardware and software since 1984. If you have questions about backup tape technology, I can probably provide an answer or can at least point you to the best resource to find one. From old (ancient ?) QIC, DLT, or MLR/SLR to the latest DAT, LTO, AIT or SDLT, I've either worked with the design team, or with the physical devices. I currently deal with Mac OS X, all of the Unix variants, and Windows platforms.

While I work for a backup software company, I promise to keep my answers non-software product specific as I try and stay on top of the posts here.

Please don't hesitate to ask questions about backup tape hardware.

Tim

[Brian Timmons]

Welcome Tim,

Backup issues, particularly on OS X, are gaining much interest on the forum lately. I'm sure your expertise will be greatly appreciated.

Your company's software has also made life easier for many of us.

Thanks.

Brian Timmons
britim media

[michael zaletel]

Hello Tim:

It's been a long time since I've used any sort of tape-based media for backup and storage. I have one question for you. What is the current state-of-the-art in tape-based backup for backing up a 16TB RAID to tape once per week for off-site storage. Cost, speed, amount of media required? At $95 for a 1TB hard drive, isn't it cheaper and much faster to just build a backup RAID and store that offsite?

Please advise,

-shooter

-shooter

[albert rudnicki]

Hello Tim
I got a question for you.
I just received a Dell PowerVoult 110T DLT 3 external unit and I paired it with a ultra320 adaptec PCI-X
I have in total 3 workstations which are Mac and PC
My network is all 1 Gigabyte.
Since it's SCSI The lto will be running on the PC platform.

The question is : can I run my DLT on the network and with what software.
I usually run the backup at the beginning of the project (r3d files) and then at the end to backup the project and master files. I don't use it on regular everyday basis.


Thank you for your help and contribution to the forum !

Best
Albert

[Tim Jones]

Hi Shooter,

While disk may seem the "cheap" alternative to tape of late, disk comes with the expense of keeping it powered and what you're plugging them into. Plus, 16TB of RAID-5 backup (I'd use RAID-6) drives would require 21 drives (1,000,000,000,000 Bytes, not 1,099,511,627,776 Bytes per drive) plus 2 RAID parity drives AND a chassis capable of supporting 21+ drives - That's $1,995. With an LTO-4 drive on a similar system, you'd need ~$1,400 worth of tapes (20) per swap. And, that's assuming that you're not using server-grade disk drives which are MUCH more expensive than $95 each.

In fact, if you search for 16TB RAID-5 arrays. you'll uncover that to get RAID-5, you're only getting 13TB of usable space. For example, the Avid VideoRAID SR is around $22K and you're stuck at 13TB usable. However, an HP MSL 2024 LTO-4 library will set you back around $9K - $10K. Add the tapes and you're only at $13K max. Seems to me that tape's a win here if we're talking solely dollar costs.

[edit] Also, keep in mind that it can take 50 hours or so to prepare a 13TB RAID-5 array for use...

As for storage, when I take an LTO-4 tape and put it on the shelf, it can sit there for 5 years (or 50 years) and I can recover it. However, if I leave disks that had spun for some period on a shelf, for every 6 months they are left "unpowered", there's an increasing probability that they will suffer from a problem known as "Sticktion" that can cause the disk to not spin back up properly when it finally is repowered (this is the #1 cause of failure in LaCie drives, IIRC).

So, if you're not in need of long term storage (archival) or you can power the drive up weekly for a period of a few hours to reduce the possibility of Sticktion, and have taken the expense of storage and connectivity into account, disk may be a good answer for you. For me, my data's too important and I trust LTO and DAT for my long term retention needs.

To performance, we have users running LTO-4 media at consistently around 100MB/sec on Intel Mac's with Fibre-Channel or SAS connectivity. This would allow for the backup of 16 TB in 46 hours + tape changes. Or, if you can split the data into smaller chunks and run multiple drives (say 4TB to 4drives) with SAS or F-C you'll see an even more useful reduction.

Just my $.02 :)

Tim

[Tim Jones]

can I run my DLT on the network and with what software.

Hi Albert,

Unfortunately, not as a device on the other systems - in other words, the Mac can't write to the tape drive on the PC. However, you could use client/server software that will use your PC as the server and treat the other systems as clients.

I'd look at Netbackup or such. Be prepared for the expense...

Tim

[albert rudnicki]

Just realize of two mistakes I made in my post. (not DLT but LTO-3:)

Is 1gig network fast enough to support lto-3 ?


Thanks Tim

[warwickt]

brumeister! wonderful to have you on the forum. your expertise and opinions are invaluable to we content creators!
w

[Tim Jones]

Just realize of two mistakes I made in my post. (not DLT but LTO-3:)

Is 1gig network fast enough to support lto-3 ?

Yes it is fast enough - with the right software (100MB/sec is attainable over that link). Glad you cleared it up about the DLT, we were all starting to wonder if you were still recording on Quad... :innocent:

Tim

[Tim Jones]

Thanks, Warwick. Glad I can share. After all, what good is knowledge if it's not shared?

Tim