how good is the data reliability with CD ROM and DVD RAM?

Grant Taylor cctalk at
Tue Jul 24 12:55:05 CDT 2018

On 7/22/18 2:06 PM, Zane Healy via cctalk wrote:
> I wouldn’t touch 4mm DAT tapes with a ten foot pole, if I can help 
> it.  I’ve used them in the past, but only in special cases, OR more 
> importantly when forced to.

I had reasonable success with DDS2 & DDS3 DATs back in the day.  I 
routinely wrote to and read from the tapes over about 18 months.  Though 
I have no idea how well they would last longer term than that.

QIC-80 drives were really before me, but I did manage to pick some up 
from garage sales and read their contents 5+ years after they were 
written.  I usually had to retention the tapes one (or more) time(s) to 
be able to get a (few) good reads off of them.  I do think they earned 
their reputation that I've heard others talk about.

That being said, CuriousMark is having decent luck with QIC cartridges 
in his old HP equipment.

> You can’t buy new LTO2 or DLT drives (I think the last DLT drives 
> were DLT8000’s).  Even Super-DLT tapes are obsolete.

I've got no personal experience with DLT.  I have multiple colleagues 
that used them to backup multiple servers (before I entered the scene).

> At this point, for tape, I recommend LTO8, and if this is for 
> Archival purposes, you’ll need to refresh to LTO9 when released. 
> LTO8 introduces an evil little gotcha.  While previous versions of 
> the drives, have been able to read two versions back, LTO8 can’t.

All of my professional experience with tape has been decidedly 
non-archival.  It was always used for nightly / weekly / monthly backups 
and consumed within 18 months.

> I’ve failed to see any reason behind your questions.  If you’re 
> looking for a long-term archival solution, look to cloud storage 
> (either on-prem, or off-prem).  Sure tape is cheap, but when you 
> start looking at other costs, such as storage and handling, it 
> becomes expensive.

I think you need to be EXTREMELY careful when selecting cloud storage 
vendors.  I've heard about a fewer smaller ones folding up shop.  I want 
to say I've heard of at least one going away fast enough that people had 
problems getting their data back.  So, make sure you pick one that is 
reputable and / or guarantees time to retrieve data that you have stored 
with them.

> This touches on one of my personal projects this year.  I virtualized 
> my backup infrastructure for my OpenVMS systems, and then I went a 
> step further, and have virtualized most of my OpenVMS environment.  I 
> still need to virtualize my DECnet area router.  While all the data 
> is moved, I’m still working to move some apps.  It makes protecting 
> my data easy.  My primary interest is the OS and software, while in 
> the past I’ve been focused on running on real hardware, 
> virtualization is looking real nice, even for working systems where I 
> have plenty of spares.

I would love to know more about how you did this.  Do you have any blog 
articles or the likes that I can read to learn?

Grant. . . .
unix || die

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