Talk:Linear Tape-Open

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Former good article nominee Linear Tape-Open was a Engineering and technology good articles nominee, but did not meet the good article criteria at the time. There are suggestions below for improving the article. Once these issues have been addressed, the article can be renominated. Editors may also seek a reassessment of the decision if they believe there was a mistake.
January 11, 2009 Good article nominee Not listed

Reference 46?[edit]

I tried to follow reference 46, but the web site requested a password. Is there an open version of these specs available? —Preceding unsigned comment added by 24.128.26.49 (talk) 14:17, 21 March 2011 (UTC)

Capacity figures[edit]

All capacity figures are assumed to be native capacity, uncompressed. It doesn't make sense to compare compressed figures. What is really getting stored on tape is just plain data. Just because it is the output of a compression algorithm, doesn't mean anything. Compressed figures have no place in the stat sheet. So we have no need to say redundant things like "Native Uncompressed Capacity." The statement is redundant.

Yes, I hate compressed figures. Yes, this is a rant. Yes, I care. Austin Murphy 19:24, 24 July 2006 (UTC)


Colours[edit]

Are the colours actually part of the standard or just the colours used by a particular manufacturer? All the HP brand 400GB LTO media I have seen was coloured dark red, which doesn't match the table in the article. --James 03:37, 18 October 2005 (UTC)


I have used HP LTO-1 (100GB/200GB) tapes, they're coloured blue.

All the LTO-2 cartridges that I have seen have been purple. I've seen Fuji, Maxell, TDK, HP, and Overland.

My cleaning cartridges are Black and are universal (across HP LTO-1 and LTO-2 drives at least).

WORM[edit]

Q: What does write-once, read-many mean in this context? Are the non-WORM varieties of tape only readable once? Or is it possible to write to them more than once?

A: It means you can write to the tape once, read it as often as you like, BUT you can't erase the tape or overwrite it. The idea is to keep some data indefinitely to meet regulatory requirements or for some other purpose. The regular varities of tape can be written and read until they wear out.

Recording characteristics[edit]

I've been googling this and the main page here is about all the info I can find!

Some of the questions I would have are:

What's the logical inter block gap (eg DDS is 4bytes, QIC is more like 2kbytes

Q: How does it react to already compressed data? (again DDS eg: logical capacity drops to about 60% if you don't physicall turn off the compression!)

A: For each data block written to tape with compression on it compares the size of the compressed and uncompressed data and writes whichever is smaller. Each block has one bit to indicate compressed or not. You can also turn off compression through a SCSI command. (Linux mt will do it.)

Q: I have found a couple of hits that the streaming requirements are easier than other tape drives, do the tape drives run at multiple speeds?

A: The HP LTO-2 Drive I use can stream at 10MB/sec to 30MB/sec. Other drives have different streaming ranges.


Later... Okay, I've put the stuff I did find eventually in the article looks like chop. chop time. 86.16.135.53 08:22, 26 March 2006 (UTC)

Units used for capacity and transfer speeds[edit]

Multiples of bytes
Decimal
Value Metric
1000 kB kilobyte
10002 MB megabyte
10003 GB gigabyte
10004 TB terabyte
10005 PB petabyte
10006 EB exabyte
10007 ZB zettabyte
10008 YB yottabyte
Binary
Value JEDEC IEC
1024 KB kilobyte KiB kibibyte
10242 MB megabyte MiB mebibyte
10243 GB gigabyte GiB gibibyte
10244 - - TiB tebibyte
10245 - - PiB pebibyte
10246 - - EiB exbibyte
10247 - - ZiB zebibyte
10248 - - YiB yobibyte
Orders of magnitude of data

As the pages for binary units, gigabyte, etc. makes very clear, there is more than one interpretation for "GB". I'm not trying to start YAUW (Yet Another Unit War) but I do think we have to either:

  • Use MiB/s and GiB as these units aren't ambiguous

or:

  • Add an explanation (perhaps in the notes section) stating that the units for this page is 2^x or 1024^y

Doldr 16:05, 6 September 2006 (UTC)


That (the addition of the unit defs) made sure that people know what we mean. Now we just have to figure out which is correct for LTO... Information about this isn't exactly easy to find (maybe someone is sitting on detailed info?). The few clues I've found seem to indicate that (like hard drives and DVDs) LTO uses 10^9, not 2^30. This is what I've found:

-- Doldr 15:32, 7 September 2006 (UTC)


Not finding any conclusive information about this I turned to "experiments". With compression off I let dd fill up two different tapes (using one of our IBM LTO3 drives). Here are the results:

  • HP LTO2 tape: 212149993472 Bytes (197.6 GiB or 212.1 GB)
  • IBM LTO3 tape: 423524040704 Bytes (394.4 GiB or 423.5 GB)

My conclusion, LTO tapes as hard drives and DVDs are spec'ed in GB (10^9). In reality tapes are manufactured to be atleast that capacity (with some margin it seems). -- Doldr 12:19, 8 September 2006 (UTC)

Interesting experiment. What was the block size for dd? It appears that neither unit system precisely describes the capacity in round numbers. 200 GB == 186 GiB, and 200 GiB == 214 GB; double that for LTO-3. Is it possible that there are error sections that are unused? I wonder if the streaming speed had anything to do with it. -- Austin Murphy 18:13, 8 September 2006 (UTC)

The template of byte quantities is pretty cool. maybe we can use it. -- Austin Murphy 18:34, 8 September 2006 (UTC)

I used 1 MiB blocksize with dd and the streaming speed was close to peak (76 MiB/s for the LTO3 and a bit under half that for LTO2). I think we should try to "get to the spec", maybe ask IBM or lto.org in some way. Doldr 09:51, 11 September 2006 (UTC)


Check out this page: ECMA 319, it looks like 100 Gbytes, the units used in the docs, means 100 x 109 bytes. -- Austin Murphy 21:17, 23 September 2006 (UTC)

Backward Compatibility[edit]

The table in the "Generations" section currently lists LTO-4 as reading only LTO-3 and LTO-4 tapes, and writing only LTO-4. This would seem to conflict with the LTO Consortium's published information, which says that any LTO drive is required to read tapes of its own generation and at least the two preceding it (so LTO-2, -3 and -4 for LTO-4 drives), and write to tapes of its own and at least the immediate preceding generation (so both LTO-3 and LTO-4 tapes for LTO-4 drives). I realise that LTO-4 has yet to be finalised, but is there any reason to expect that the prior policy on backward compatibility will change? -- 210.54.3.3 07:13, 22 November 2006 (UTC)

I would prefer to delete those two rows from the table since they describe something other than that specific generation of LTO in that column. The rows ("Reading" and "Writing") describe interoperability between generations and do a poor job of it. The previous section describes it suitably anyway. -- Austin Murphy 22:27, 26 November 2006 (UTC)
I deleted those rows. -- Austin Murphy 15:28, 27 November 2006 (UTC)

Tape wear[edit]

Am I reading this article correctly w/respect to the number of passes over the tape required to fill a tape to capacity? It sounds as if an LTO-1 drive requires 48 end-to-end passes, while an LTO-2 drive requires 64 passes. What are the implications to tape wear and head wear? How does this compare to helical-scan tape formats? -- dpotter 23:52, 5 February 2007 (UTC)

You are reading it correctly. X total tracks / Y tracks per pass (head elements) = Z total passes. 512/8=64. In this configuration the head is essentially fixed while in a helical scan configuration the head is rapidly rotating against the tape. A helical scan configuration will only make one pass over the tape. Both cause more tape wear than one with knowledge of audio tapes might expect. I don't know which causes more wear. As an aside, I've heard that older rented VHS tapes frequently have a loss of signal at certain particular points on the tape. This is due to the pause function keeping the spinning tape head at the same spot on the tape, slowly wearing away the magnetic coating. You don't get this with linear tape systems, because "pause" is not even possible. Shoe-shining is a problem with high-speed linear serpentine tapes. If a drive is shoe-shining, then it is effectively making many more passes than normal. -- Austin Murphy 19:13, 6 February 2007 (UTC)

HH (Half-height) drives[edit]

I feel half-height drives should be mentioned for LTO-2 & LTO-3 (and very soon LTO4). Perhaps only a short excerpt about how they operate at ~3/4 the data transfer rate of their full-height counterparts but take up only half the size height-wise? Being that they still use the same media as they are named after, capacity of course does not change. -- halfmoon 01:48, 31 August 2007 (UTC)

Dells HH LTO-4 Tape Drive does have same data transfer speeds as it's full height sibling! [ http://www.dell.com/downloads/global/products/pvaul/en/tbu_drives_comp.pdf ] —Preceding unsigned comment added by 212.254.33.106 (talk) 13:57, 14 April 2010 (UTC)

Agreed with this. I've been troubleshooting an issue and using the excellent page as reference. I discovered the HH issue yesterday and have wasted a lot of time!! Had the HH info been there I wouldn't have. I'll be updating the page again now to at least point out this discrepancy. I've read 70% of FH throughput for HH drives but I need a good source to cite before I can add that fact. Notverynick (talk) 13:37, 4 September 2013 (UTC) notverynick

Fair use rationale for Image:Lto-logo.png[edit]

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BetacommandBot (talk) 20:13, 2 January 2008 (UTC)

GA Review[edit]

This review is transcluded from Talk:Linear Tape-Open/GA1. The edit link for this section can be used to add comments to the review.

This article does not meet the good article criteria and has too many issues. It has therefore failed its nomination. Issues include but are not limited to:

  • Needs more references per WP:CITE
    • "Form factors" has no references
    • Most of "Technical features" has none

That's about half of the article.

Questions and comments placed on this page will receive responses. Once these issues have been resolved, feel free to renominate the article. Thanks! Gary King (talk) 06:29, 11 January 2009 (UTC)

SCSI[edit]

I noticed that all Ultrium/LTO devices on the market appear to be SCSI-only. Is there something in the specification that requires only SCSI devices? -Rolypolyman (talk) 06:17, 5 April 2009 (UTC)

"IBM called their cartridge 3480 and DEC originally called theirs CompacTape, but later it was renamed DLT and sold to Quantum." 

Excuse me, this is ambiguous. Which "it" was renamed and sold, DEC's or IBM's? Or were they the same thing? Were their specs different? Did they co-operate on the format? Can you put a link to the hacker's dictionary definition for 'squaretape'? —Preceding unsigned comment added by 38.105.85.100 (talk) 16:10, 26 January 2010 (UTC)

I think the 'History' comment is wrong. Both DLT and 3480 came out in 1984. DLT was 'low performance' and relatively cheap, and not available as channel attach. The 3480 technology was (I think) fundamentally different, and not even a competing standard as it was mainframe rather than micro/super micro. — Preceding unsigned comment added by 144.191.148.3 (talk) 15:10, 16 June 2012 (UTC)

I agree that 3480 and DLT are completely incompatible and serve different markets, but they both have linear, multi-track, half-inch tape in a square-ish cartridge. It is mentioned because LTO was built using IBM's technology (3480 & successors) and was aimed at DLT. --Austin Murphy (talk) 19:13, 25 June 2012 (UTC)

Data transfer rates[edit]

"The units for data transfer generally follow the binary prefix convention. (eg. mega = 2^20)"

Is there any reliable source for that? Data transfer rates hardly ever are given in binary prefixes. --GlaMax (talk) 13:43, 27 April 2010 (UTC)