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DTL vs LTO open discussion

Sebastien Masson
Valued Contributor

DTL vs LTO open discussion

Hi all folks,

In mid 2000 I built a new backup infrastructure with DLT technology. Follow my plan, I ask a DLT 2/15 library and the plan ask the use of 700 DLT tape for offsite, on site, dev, etc.. backup. After two year, you hare on plan of 700 DLT but my library is not enough for what we need to backup, so I ask my manager for a new DLT library. My manager come to me and said someone from HP offer a LTO library for nearly the same price as the DLT I ask.

Now, I don???t think is a good idea to switch to a new technology since we already invest for DLT tape (700) and we not full up tape we send outside each day.

I need to help here. Do LTO is really better then DLT. The investment in that technology is a good thing?

Please fell free to comment, I want an open discussion on DTL vs. LTO, the best and the worst...

Your help is very appreciated...

For you are interested, I currently run with a DLT7000 2/15, omniback II v4.1, I backup some few N4000 on gig interface and my backup station is a A500 on gig also.

Sabey
16 REPLIES
H.Merijn Brand (procura
Honored Contributor

Re: DTL vs LTO open discussion

We upgraded from DLT7000 to DLT8000 and do not regret it. *Much* faster, and supporting larger tapes.

We do full backups of all our (not only HP) unix systems over the LAN at night. So far it still fits within the 40 Gb limit (given we've told the backup process not to include huge static directories that we backup once a month on a different tape)

HTH
Enjoy, Have FUN! H.Merijn
Jason VanDerMark
Trusted Contributor

Re: DTL vs LTO open discussion

We were in a similar situation where I work and we ended up going with the StorageTek 9940 drives/media. They too are nice, but in hindsight we should have gone to the LTOs. I can tell you that with any media that is not DLT(LTO, 9940, etc.) they are all a lot more reliable solutions as you don't drop tapes very often at all. I hope that this helps.

Regards,
Jason
Tie two birds together, eventhough they have four wings, they cannot fly.
A. Clay Stephenson
Acclaimed Contributor

Re: DTL vs LTO open discussion

Hi:

When I started with my current employer, I was faced with tha same hardware. The consultant had recommended and the company had purchased a 2/15 DLT7000. It was obviously too small to handle the task and I pointed that out on my 2nd day on the job. The news was not well-received but we did purchase a larger unit and I still use the 2/15 for PC Server backups. The other problem with the 2/15 is that it does not have a mailslot so that you have to manually open it to change media.

Your choice is only made difficult because of the very large investment in DLT media. If that were out of the picture, the decision would be trivially easy. The price of the media is roughly equivalent but the throughput and capacity is more than 2x your current capacity. I really don't let the speed of backup influence my decisions because no matter how fast it is, it's not fast enough. You really have to look at snapshot methods so that then you don't care how fast the backups are.

Here's my best advice (and you can use it for what it's worth): I would stay with DLT. Your roughly $49K in existiing DLT media can buy at least 2 more drives and more library slots. In Omniback, having more drives (and the flexibility that gives you) will probably prove to be more important. You can also keep your 2/15 in service; just let it do jobs for which it is better suited. P.S. You can copy media from one DLT library to another.

Food for thought, Clay

If it ain't broke, I can fix that.
Sebastien Masson
Valued Contributor

Re: DTL vs LTO open discussion

Hi A. Clay,

After few hour with the HP vendor, my choice stay on the DLT technology and a choose a DLT 8000 4/40 to replace my old DLT 7000 2/15. And like you said, I can alway keep my old library for other purpose without loose my already tape investment.

Thanks
Michael Tully
Honored Contributor

Re: DTL vs LTO open discussion

Hi,

Although the LTO does out perform the DLT, I think you should stick with your current media type. As mentioned by Clay you probably already have a significant investment in your current tapes. The cost I think would outweigh the performance that you would get by changing over.

Michael
Anyone for a Mutiny ?
harry d brown jr
Honored Contributor

Re: DTL vs LTO open discussion

Sabey,

I always found that punch paper tape was better, because you can actually read the characters, plus the punchies are great for parties. Seriously, if your boss is serious, ask her/him how much money they are willing to spend on switching from DLT to LTO.

live free or die
harry
Live Free or Die
Rick Garland
Honored Contributor

Re: DTL vs LTO open discussion

There are many pros and cons whichever way you decide to turn - just no getting away from it.

I did have a similar issue and fortunately (and I do mean forunately!) I was able to convince the powers that be to invest in using both types of drives. In this manner I believe I have minimized the cons of the argument. So if the money is not an issue, you can go both ways while still retaining your investment in the DLTs which are going to be around for quite some time.
Vincent Farrugia
Honored Contributor

Re: DTL vs LTO open discussion

Hello,

At face value, LTO is much better, otherwise they wouldn't have launched it if it were worse. 100Gb native capacity compared with 40Gb, 15Mb/s native speed compared with 6Mb/s, that IS better no? Mmm I realise that I'm mentioning the DLT8000s specs, not the DLT7000... DLT7000 is somewhat slower than that still...

That said, Ultrium is designed to be used by people having loads of Gb to backup. So my answer is, it depends on how many Gbs you have to backup daily. If you have a read lot, say an XP256 or something like that, Ultrium is the guy, no question. But if you have a somewhat smaller amount of Gbs to backup up, go with DLT.

BTW, you may do well to upgrade your DLT7000 to DLT8000. There are a lot of libraries from which you can choose from. Follow this link for more information on libraries and which take which drives:

http://www.hp.com/products1/storage/products/automatedbackup/index.html

HTH,
Vince
Tape Drives RULE!!!
Phil Daws_2
Regular Advisor

Re: DTL vs LTO open discussion

I believe that HP will not be supporting SDLT in the future. We have just swapped out 6 SDLT for 10 LTO with 5 CrossOver Bridges. Plus a nice pack of 300 LTO tapes ;)

Roch Bourdon
Occasional Contributor

Re: DTL vs LTO open discussion

One of the reasons we choosed a DLT8000 vs a LTO was because the throughput of the LTO (1st generation) is not much better than that of the DLT8000. (Looks like a bit more than the double if you look around on HP's site) But in fact the numbers for the LTO are with compression and the numbers for the DLT800 are native speeds (not compressed). So they are about the same speed :) Marketing...
Jan Klier
Respected Contributor

Re: DTL vs LTO open discussion

On which numbers did you base your observation?

LTO drive (230):
* 15MB/s native sustained transfer rate
* 30MB/s sustained transfer rate assuming 2:1 compression.

DLT 8K:
* 6MB/s native sustained
* 12MB/s sustained transfer rate assuming 2:1 compression

(data taken from specification files of external HP site).

LTO drive is definitely superior in transfer performance, so much though that on many systems the system can't keep up with the drive to keep it streaming.
Martin Johnson
Honored Contributor

Re: DTL vs LTO open discussion

When we faced this decision, we felt that Super DLT was the way to go. To get the higher densities, calibrating tracks are required. In LTO, these are magnetic tracks on the back side of the tape. If your tape is accidentally degaussed, the tape is useless. SDLT has a metalic track.

Overall, we found SDLT to be technically superior. I thought it was really cool to watch a SDLT tape drive do a backup while being shaken in a paint mixer! No errors!

Unfortunately, HPs lack of vision with repect to SDLT, we decided to go with Veritas Netbackup using ATL robotic drives. Preserving our investment in DLT7000 and DLT8000 was also a factor.
Leif Halvarsson_2
Honored Contributor

Re: DTL vs LTO open discussion

Hi
I was in a situaton similar to yours. We was planning for a new backup solution and had lot of DLT tapes from our old systems (DLT400 and DLT7000).
The question was DLT8000 or LTO.
I choosed LTO because a LTO solution was mutch cheper (samller library and fewer OmniBack licenses). I plan to use DLT tapes (and some of the old equipment) for archive purposes. There is a problem because OmniBack dont support copying data from a LTO to a DLT device, I need to run a extra backup session for this archiving.
Jan Klier
Respected Contributor

Re: DTL vs LTO open discussion

If you need to copy from DLT to LTO, you can actually use HP Library & Tape Tools (HP's diagnostic tool). Under the utilities menu it has a media migration function for just that purpose. And it should provide instructions for the various backup applications, in order for them to recognize the copied tapes.
Raul_7
Occasional Advisor

Re: DTL vs LTO open discussion

I meant to reply to this message but ended up with a new message. Please look up my two cents to read my responds.
Good things come to those who wait, "let the backups finish"
Julio Valero
Occasional Advisor

Re: DTL vs LTO open discussion

It's not a waste to purchase new LTO. We did and still have on production out DLT investment.

Addind LTO libraries will reduce the backup window, as well as will help you to success on backing up all of the required data.

We have DLT & LTO, LTO libraries do the backup of those servers with some hundreds of GB's of on line storage. DLT are now our backup player for the backup infrastructure.