Comments & Opinions
Home Page | Comments | Articles | Faq | Documents | Search | Archive | Tales from the Machine Room | Contribute | Set language to:en it | Login/Register
I received a mail from Mirko Schiavolin (thanks for the notice) that suggests the following article from 'il post':
"Il futuro promettente dei nastri magnetici".
Now, let's ignore the fact that it simply report what somebody else already wrote without adding anything new, but there are a few things that are incorrect (evidently whoever 'wrote' it didn't spent too much time thinking or researching the matter), so is worth to give it a look.
We're talking, as you can gather from the title, of magnetic tapes. Those things that have been used (and still are) for decades in datacenters. Since the beginning of the '80s when you wanted to show a "computer" in the movies, what you do? You put a picture of an IBM tape unit and voila', computer!
Why tapes? Well, simple. The demand was to have a thing that could be read and wrote, so things like vinyl was out, and whoever was asking was already spending an arm and a leg for the computer, throw in also a kidney and get a tape drive! Because, yes, the technology was very expensive at the time but they got the job done and in a relatively simple way.
The mechanical part of the thing was relatively simple, what was very expensive was the tape itself. Then, in the quest to increase the speed at which data could be read and wrote, we got stuff like ermetically sealed readed, when after the installation of the tapes air was sucked out of the unit to reduce drag and dust, and the cost of the units also increased.
Then... Technology improves and we get faster, bigger and cheaper disks...
And here we need to put a note. The article, also the original from the Economist, that doesn't look to me like a very "tech-savy" publication, refer to disks as "more practical because you don't have to rewind them". Well, yeah, but the major difference between the two technology is that disk have a data STRUCTURE while tapes don't.
What does this means? That before you can use a disk you have to "format" it. During this operation the surface is divided into sectors, and each sector is assigned a unique number. This way you can jump from one data block to another with precision, doesn't matter where you are at the moment.
Tapes... No. A tape is read from the beginning to the end as a long, very long, uninterrupted sequence of data. The only way to go from one point to another is to know where that 'other' point is from the beginning of the tape, go that point (more or less) and read. And this require a lot of time to be performed and a very precise mechanism to count the length of the tape. And this increase the cost and, in short, make tapes unadapted for specific applications.
Databases for example. Where an information refer to another information somewhere else. And when you want to put all together, you need to read pieces here and there, and to do so you need to be able to jump from one data block to another quickly. And if you have a tape, there is only one way: read the whole thing into memory. And memory was REALLY expensive at the time. Because they were made with large components, used a lot of power and generated a lot of heath.
That's why all companies pursued disk technology. The result was that disks, from slow, expensive and big (in size, not in capacity), became quickly fast, cheap and huge (in capacity, not size) and the main method of data storage.
But tapes did not disappeared, they kept being used for "other" uses, no longer "the" storage method but just "a" storage method. Particularly useful when the speed of access to data isn't that important but capacity is. Because the surface of a disk is... what it is. But a tape can be made longer... theoretically as long as you want.
Obviously there is a limit to the length of a tape, beyond which, it gets so heavy that it breaks when the drive try to pull it for reading, but technology helped there too, moving from cellulose to plastic and making magnetic heads smaller, reducing the size required for data storage.
So... high capacity, low speed... what is good for? Well, initially, mostly backup. Basically a backup is a copy of the data that is kept for security, you don't need to access it every 5 minutes and when you do, you can wait a few hours 'cause there is no alternative. As long as it takes less than a day to write it of course.
But... Time passes, technology improves and disks grows... a lot.
We went from few megabytes to hundreds of Megabytes and then we saw the 'G' of Gigabytes and then they came with several hundreds of them.
And with better technology, the prices went down. The use of software solution for data duplication (RAID) allow the creation of arrays, that uses lots of cheap disks to create an high-speed, high-capacity, high-redundancy solution, that is even better than tapes for backups.
Tapes moved to an even more "niche" application. A bit like vinyl disks moved to "vintage".
Now, the article here makes a bit of a mistake and reports:
Hemmm... No. Magnetic TAPES as support, are maybe less expensive that one hard disk, but the tape alone is useless, to be used you also need the other part of the hardware: the drive, that is a lot more expensive than one disk. We can argue that you only need to buy one drive to use multiple tapes, but then the discussion gets a lot more complex.
Also, tapes have "mechanical parts" too that are subject to "wear and tear", they are even MORE subject to it because the mechanical part of a disk are sealed into the disk itself, protected from dust and vibration, while tapes aren't. Unless you use a drive that is A LOT more expensive.
When a disk breaks, in many cases the part that brakes isn't the 'disk' itself, and you can move the platters to a 'donor' disk and get your data back. When a tape breaks... Well if it breaks on its own, in many cases it's trashed and when it breaks INSIDE THE DRIVE... You maybe need to trash also the drive. Unless is the drive that breaks and then you have to replace it.
On the other hand, disks are the most stressed when they start, because the platters goes from "stop" to "spin very fast". The longer a disk remain still, the more problem you have at the start. That's why is better to keep machines running all the time: is less stressful for the disks. On the other hand, you can manually wind a tape, "unlock" it before putting it into the drive, reducing the mechanical stress.
Also, let's not forget that both devices are magnetic, and magnetism ain't eternal. Usually, tapes older than 7 years should be considered "spent" and no longer usable.
So, that short sentence there... Deserve some more discussion.
But the article also has some base of truth: many companies keeps using tapes, not as backup per se, but something similar: archiving.
And you ask: and what is the difference? And I answer: a lot.
A backup is a copy that is made for security and after a while you need to take another one and after a while the oldest 'copies' are 'recycled'. This means that there is a finite numbers of copies that are kept around as backup. And if something bad happens, being able to access those data quickly and safely is very important.
An "archive" instead, is composed by "historical" data that keep being added to it. Accessing those data is, usually, not that important. Sure, you want to be able to get them, but if you realy to need to check the invoices of 10 years ago, I think you can wait a few hours (or a day) without dying...
Now, this is where tapes are in use.
If we look at the various solutions that are in use today, almost all the 'cloud' vendors have some sort of "data archiving" solution that has 2 characteristics: is very cheap for the data stored, but has very slow (and expensive) access to read the data back.
Different vendors uses different names, but the concept is the same.
Why all this? Well, in many cases the requirements is legal, in many countries there is a mandate to keep financial data for a certain numbers of years, this stuff is probably no longer actively used but have to be kept somewhere. And instead of keeping a bunch of disks spinning all the time, is easier to have a closet full of boxes with tapes and one machine with a drive. If there is a request, you send the intern to pick up the right box and load the data into a temporary disk while the box with the tape goes back to the closet.
So, what do I think about this?
That even here technology is getting better. Solid state drives (SSD) are getting less and less expensive, tapes still have some use as long as commodity and convenience are on their side but when the price of support and drives goes beyond some point...
And increase speed and capacity of tapes means that you also need to completely replace everything (the tapes and the drive). And all the old tapes needs to be re-read and written in the new format, increasing costs and time (I assume here that you want to keep everything omogeneus to avoid problems with incompatibles formats).
So, the technology is still in use but is it still worth improving it?
I am not sure...
As said, having to replace everything to chase the last version is not something that every company is willing to do, especially if the old system still works fine and cover the needs. There is, of course, the problem of getting new tapes, since this is a now almost moribund technology, not many manufacture are making new tapes or parts for the drives.
And if you decide to jump to the next iteration, what you do with the old stuff? The tapes are going stright to trash and the drives... almost...
So... I am not completely convinced that this technology is worth pursuing anymore. Is like keep trying to improve CRT displays.
For my part, I have a small, cheap synology that works fine for my needs.
Comments are added when and more important if I have the time to review them and after removing Spam, Crap, Phishing and the like. So don't hold your breath. And if your comment doesn't appear, is probably becuase it wasn't worth it.
By Daniele Levi posted 11/01/2021 12:22 - reply
Chissà com'è, mi è subito venuta in mente una certa TAPELIB SONY....-- Chi conosce tutte le risposte non si è fatto tutte le domande.
@ Daniele Levi By Davide Bianchi posted 11/01/2021 12:29 - reply
Chissà com'è, mi è subito venuta in mente una certa TAPELIB SONY....
Si', pensando che se quella tapelib fosse stato invece un volgare pc con una batteria di dischi in raid, collegato via NFS/SMB/FTP... non ci sarebbero stati tanti problemi.
-- Davide Bianchi
By Anonymous coward posted 11/01/2021 14:03 - reply
Sono d'accordo con quasi tutto quanto detto in questo post. Un aspetto importante dei nastri (e anche dei supporti magnetici e/o ottici rimovibili) che però si tende spesso a dimenticare è la loro natura off-line. Se da un lato questo è uno svantaggio (bisogna fisicamente cercare il supporto coi dati di interesse ed inserirlo nel lettore, a meno che non si usi una libreria), per contro ha il grande pregio di mettere al riparo i dati da errori accidentali. Infatti, se il supporto non è inserito, non è possibile cancellare o alterare i dati e, anche se è inserito, molti tipi di cartucce hanno un "interruttore" per impedirne la scrittura a livello hardware (come con i vecchi floppy disk). Con l'emergere di ransomware e altri attacchi informatici, rendere fisicamente impossibile la cancellazione o alterazione dei dati non è cosa di poco conto, specialmente in un contesto come quello dell'archiviazione a lungo termine discusso nel post.-- Anonymous coward
@ Anonymous coward By Anonymous coward posted 14/01/2021 17:34 - reply
Con l'emergere di ransomware e altri attacchi informatici, rendere fisicamente impossibile la cancellazione o alterazione dei dati non è cosa di poco conto, specialmente in un contesto come quello dell'archiviazione a lungo termine discusso nel post.
Ehm... mai sentito parlare di Centera?
-- Anonymous coward
@ Anonymous coward By Davide Bianchi posted 15/01/2021 07:11 - reply
rendere fisicamente impossibile la cancellazione o alterazione dei dati
Ehm... mai sentito parlare di Centera?
A parte quello, puoi sempre disabilitare la scrittura sui dischi. E si', si puo' fare a livello hardware.
-- Davide Bianchi
@ Davide Bianchi By Daniele Levi posted 15/01/2021 10:54 - reply
>> A parte quello, puoi sempre disabilitare la scrittura sui dischi. E si', si puo' fare a livello hardware.
Ecco, ammetto che questo non lo sapevo...
-- Chi conosce tutte le risposte non si è fatto tutte le domande.
By Cimpy posted 11/01/2021 14:11 - reply
Coi nastri, poi bisogna tenere pronta la matita per quando scarrucolano e devi riavvolgere la cassetta...
... Ah no, non quei nastri!
By Messer Franz posted 11/01/2021 14:28 - reply
...mi hai fatto ricordare quando i floppini sono diventati i flopponi, ma sono morti subito causa l'arrivo dei CD (e secondo me del nome schifoso, cioè, "flopponi"? Inventatevi un soprannome decente!)...e il mio primo PC (1998) con Windows 95.c e BEN 140 GB (o 160? Ho dei dubbi) di Hdd...ma d'altra parte la RAM era di 256mb, chi può desiderare di più?-- Messer Franz
By Francesco Da Riva posted 11/01/2021 14:59 - reply
Bellissima la ricostruzione storica ma non concordo sulle conclusione.
Lo Standard LTO è uscito nel 2000 da allora il nuovi lettori hanno sempre rispetatto la regola di poter leggere almeno le due generazioni precedenti di nastri.
La persistenza minima garantita, su nastri che rispettino il massimo numeri di cicli di utilizzo, è di 15 anni.
Altra cosa fondamentale: nessun rasomware riesce ad attaccare un nastro, un backup in linea è sempre vulnerabile.
Un backup in cloud, ben configurato, è ottima cosa, molto meno vulnerabile di qualsiasi soluzione in linea di casa, ma affiancargli dei backup su nastro aumenta non di poco la resistenza agli attacchi.
By D'oh? posted 11/01/2021 15:26 - reply
Ma quando i nastri andranno a morire, i giornalastri la smetteranno di sparar minchiate a nastro?-- D'oh?
By Anonymous coward posted 11/01/2021 16:06 - reply
Apro una parentesi, dai contenuti deve essere lo stesso articolo che vedo pubblicato ogni tot anni ormai da fine anni'90....
Probabilmente perchè parlare di nastri a una platea di newbie che si è formata sui cataloghi hardware della stagione in corso fa molto figo "vecchia scuola".-- Anonymous coward
By Anonymous coward posted 11/01/2021 19:46 - reply
Mi tornano in mente i vecchi tempi con il Commodore 64, e la superiorità dell'unità floppy 1541 rispetto alle cassette e al Datassette!
Riguardo il discorso di continuare ad evolvere la tecnologia dei nastri o no, basta pensare a quello che è successo con i cd e i dvd: il tentativo di evolverli ulteriormente con il bluray non è andato lontano...-- Anonymous coward
By Thomas posted 12/01/2021 00:09 - reply
<i>a parte che un post che riporta quanto gia' scritto da qualcun altro senza aggiungere niente non e' che valga un gran che</i>
Piu' che un Post, stavolta, e' un RePost!
Battute a parte, come testata generalista rimane la crema del settore in Italia. Son bravi, di solito.-- Thomas
This site is made by me with blood, sweat and gunpowder, if you want to republish or redistribute any part of it, please drop me (or the author of the article if is not me) a mail.
This site was composed with VIM, now is composed with VIM and the (in)famous CMS FdT.
This site isn't optimized for vision with any specific browser, nor
it requires special fonts or resolution.
You're free to see it as you wish.