Wikipedia:Reference desk/Archives/Computing/2015 July 10

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July 10

An open-source scheduling system

Hi there,
I look for a scheduling system, which sets employees according to their demands,
and can update it in an exchange server. 14:03, 10 July 2015 (UTC) — Preceding unsigned comment added by Exx8 (talk • contribs)

old school AOL screen names

I'm writing a historical novel that takes place around 1996-1997. What were the requirements restrictions for screen names back in the heyday of America Online? How many characters minimum/maximum? What types of characters were allowed/disallowed? Since your screen name was also your email address (if i recall correctly), I'm sure this severely limited what your name could be.--Captain Breakfast (talk) 14:14, 10 July 2015 (UTC)

I checked my archived files, which I knew contained a mailing list for AOL from the mid-90s. The character set for over 2,000 AOL addresses is a-z A-Z 0-9 and _. I didn't see a single dash or period. There are many names that are 15 characters long, but none longer than 15 characters. While this is not the rules from AOL, it is a representation of the result of AOL rules. So, if you are looking for names that look plausible, you can stick to alphanumeric strings of 15 characters max, with use of the underscore as necessary. 199.15.144.250 (talk) 13:30, 11 July 2015 (UTC)

Wow, that is extraordinarily helpful. Thank you!--Captain Breakfast (talk) 23:34, 11 July 2015 (UTC)

Hard drive holes

Why do hard drives have "void holes" on them covered by a sticker that if removed will allow atmosphere into the drive platters and ruin them? They say "void if removed" or similar. What I mean is, the purpose seems obvious to ruin the drive my question is why are they part of the design of drives that 99% of people will not want to ruin? It's like putting a hole covered by a sticker on every car tire that says "void if poked with a drawing pin". Why include it as part of the design? — Preceding unsigned comment added by 120.206.155.12 (talk) 14:29, 10 July 2015 (UTC)

Uh, I don't the platters being exposed to atmosphere would damage them. A hard drive is a magnetic storage medium. Therefore, they most likely wouldn't be affected by exposure to oxygen. Although they could be affected by rust. However, this would require an oxidization agent like water. Now if you took some magnets and waved them closed to the drive, thats another story. That's pretty much the most effective way to erase data from a hard drive. —SGA314 I am not available on weekends (talk) 16:48, 10 July 2015 (UTC)

The atmosphere contains dust and dust can cause a head crash. -- BenRG (talk) 17:00, 10 July 2015 (UTC)

True, I didn't think of that. —SGA314 I am not available on weekends (talk) 17:30, 10 July 2015 (UTC)

I don't think such holes exist. Most drives I've seen have a hole for pressure equalization with a label saying "do not cover this hole". If there's a sticker saying "warranty void if removed" it probably covers a screw or otherwise prevents you from opening the drive case. -- BenRG (talk) 17:00, 10 July 2015 (UTC)

Thank makes much more sense as for I have seen stickers on many other products that cover screw wholes. —SGA314 I am not available on weekends (talk) 17:31, 10 July 2015 (UTC)

Typical hard drives are open to atmosphere, albeit with a filter in between the outside air and the inside. See our article. However I agree with BenRG; I'm not sure the stickers you're talking about are covering the breather hole. --108.38.204.15 (talk) 08:10, 11 July 2015 (UTC)

The drive is very sensitive to dust. I recall an analogy that may help...if one track of the hard drive was as wide as a 6 lane road, the drive head would be the size of a 747 airplane, flying at an altitude of about three feet. On that scale, a human skin cell (a common component of dust) would be the size of a car. Clearly, dust is a bad thing.

So the common trick is to arrange for there to be positive air pressure inside the drive, so that even if there is a tiny leak, air will escape from the drive and not leak into it. But there are several approaches to doing this.

Parts of a HDD

That said, I agree that the stickers are probably covering screws, which if removed would result in the likely-hood of dust getting into the drive and wrecking it. Some other drives have a waxy plastic substance (ogjpoured into the screw holes so that it's evident if they have been tampered with. SteveBaker (talk) 22:20, 12 July 2015 (UTC)

I've mucked around with dead hard drives before, because taking things apart is interesting, and the little stickers the op is talking about definitely exist and are not covering screw holes. There is just a void if you poke through it. Could it be something to do with the manufacturing process, like this hole is needed to remove air from the inside, or to fill it with an inert gas, and then the hole is sealed? I'm just guessing at this point, but mostly posting to confirm these holes do exist and aren't covering screws. 81.138.15.171 (talk) 09:02, 13 July 2015 (UTC)

Enlarge the picture and see the notes by hoovering the mouse over it, there on commons, only. Below the breather, a filter is installed to keep the dust of. Another filter is installed in the dirve to catch any particles in the airflow from the rotating platter. --Hans Haase (有问题吗) 22:17, 13 July 2015 (UTC)

Hmmm - I checked the numbers on my disk head/747 analogy. The numbers are a bit outdated! current 'fly height' of a modern hard drive is about 3 nanometers - and a human skin cell is about 30,000 nanometers across. So if the 747 is flying 10 feet off the ground, the skin cell is the size of mount everest! SteveBaker (talk) 22:30, 13 July 2015 (UTC)

Indeed, is gives litten addition to the known analogy diskheads vs Boing 747. But the heads are parked on the inner side of the platters and the platters speed up first before the heads leave the parking position. 20 Years ago WD made a frimware bug making the heads leave before completing the spin up. ASUS M/Bs booted very quick and accessed the drives before spin up. The problem was WD not ASUS, but in the BIOS a delay for spin up could set. If any human skin cell is not gluing on the platter, it has the chance to be blown into the inner filter pad. --Hans Haase (有问题吗) 12:19, 14 July 2015 (UTC)

4g pocket wifi slow issues

If a 4g pocket wifi module is a lot slower than advertised is the problem likely to be the 4g or the wifi? 90.198.254.18 (talk) 18:53, 10 July 2015 (UTC)

A 4G connection is shared with other users on the repeater, also known as mobil phone network cell. WIFI from Your router is a dedicated DSL on Your phone line. Public WIFI is also shared with other users. This does not affect any if all the users do not overload by demand the installed bandwith. --Hans Haase (有问题吗) 22:25, 13 July 2015 (UTC)