Wikipedia:Reference desk/Archives/Computing/2013 April 7

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April 7

Download

Hi all,

Could you please answer this question about IT (I don't know much about it). If I download a file and then put it on a USB stick, does the file have any "print" of my computer? I mean, can anyone know this file was downloaded to my computer before being transferred to the stick? Thanks a lot!

92.97.154.11 (talk) 02:05, 7 April 2013 (UTC)

Assuming you meant "Does it leave any trace ?", then, probably, yes. To be certain to avoid this, you'd probably need a read-only operating system, which can't possibly save any info, or you'd need to reformat the entire hard disk, after. Otherwise, some kind of tracker program running on the computer could keep a record, no matter how hard you try to prevent it.

However, saving directly onto the USB stick instead of first to the hard drive might minimize the trace, such that only the names of the files and times of downloads are stored on the hard disk, assuming nobody has installed a tracker program. StuRat (talk) 02:42, 7 April 2013 (UTC)

To remove any trace of your download:

Do as StuRat said and delete your browsing history for that time period so it doesn't look suspicious.

RunningUranium (talk) 02:59, 7 April 2013 (UTC)

The OP actually seems to be asking whether the file on the USB stick can be traced back to his computer, and the answer is almost certainly no. The file should be passed untouched from the download to your hard drive to the stick, and won't have anything added by your computer. Rojomoke (talk) 04:38, 7 April 2013 (UTC)

It will depend on the file though, some things like Microsoft Office documents tag the 'author' of the document - so if it was created on the PC and transferred to the USB it may still include the name of the computer (not necessarily something that will make it easy/realistically possible to track down the PC though). E.g. at work our laptops get a unique number as their 'name', any Word documents I create on it show that number in the author field in the properties. ny156uk (talk) 08:02, 7 April 2013 (UTC)

True, but the possibility of that will be much reduced if you don't open the file (with Word or whatever program it comes from) before passing it on. If the OP could tell us what kind of file it is, we could give a more definitive answer. Rojomoke (talk) 08:41, 7 April 2013 (UTC)

HD tune results

I'm running HD Tune (see above) and at this point the results show

HD Tune Pro: ST32000641AS Health

ID                                  Current  Worst    ThresholdData         Status   
(01) Raw Read Error Rate            118      99       6        189990865    ok       
(03) Spin Up Time                   100      100      0        0            ok       
(04) Start/Stop Count               100      100      20       119          ok       
(05) Reallocated Sector Count       100      100      36       0            ok       
(07) Seek Error Rate                87       60       30       469998064    ok       
(09) Power On Hours Count           82       82       0        16046        ok       
(0A) Spin Retry Count               100      100      97       0            ok       
(0C) Power Cycle Count              100      100      20       118          ok       
(B7) (unknown attribute)            100      100      0        0            ok       
(B8) End To End Error Detection     100      100      99       0            ok       
(BB) Reported Uncorrectable Errors  100      100      0        0            ok       
(BC) Command Timeout                100      99       0        1            ok       
(BD) (unknown attribute)            100      100      0        0            ok       
(BE) Airflow Temperature            60       57       45       689831976    ok       
(BF) G-sense Error Rate             100      100      0        1            ok       
(C0) Unsafe Shutdown Count          100      100      0        46           ok       
(C1) Load Cycle Count               100      100      0        119          ok       
(C2) Temperature                    40       43       0        40           ok       
(C3) Hardware ECC Recovered         54       27       0        189990865    ok       
(C5) Current Pending Sector         100      100      0        0            ok       
(C6) Offline Uncorrectable          100      100      0        0            ok       
(C7) Ultra DMA CRC Error Count      200      200      0        0            ok       
(F0) Head Flying Hours              100      253      0        16368        ok       
(F1) LifeTime Writes from Host      100      253      0        -1989403685  ok       
(F2) LifeTime Reads from Host       100      253      0        -1902847635  ok       

Health Status         : ok

Looks like almost 190 million raw read errors. But it says OK. Do these error numbers seem reasonable? Bubba73 ^{You talkin' to me?} 03:24, 7 April 2013 (UTC)

From what I understand from [1], threshold is not the number of errors, but rather the limit. Your current test has 118 read errors, and before that the most number of errors was 99. The link I found doesn't show two values for Threshold. Maybe the program's help is more current or explains it better. RudolfRed (talk) 03:38, 7 April 2013 (UTC)

No, the "current", "worst", and "threshold" values are not counts of anything; they are abstract health values where higher is better and 100 (or sometimes 200 or 253) is normal. "Threshold" is a manufacturer-chosen constant value that's supposed to indicate the point at which you should think about replacing the drive. The "data" value is sometimes an actual count (as in "Power On Hours Count" and "Power Cycle Count").

The most relevant statistics here are the ones related to bad sectors: "Reallocated Sector Count", "Reported Uncorrectable Errors", "Current Pending Sector", and "Offline Uncorrectable". All of them are zero. That means the drive has never reported an I/O error to the operating system, so whatever error you're getting from Carbonite is not a drive hardware problem. -- BenRG 04:53, 7 April 2013 (UTC)

The HDTune test finished and those still show zero. You asked what error I was getting from Carbonite - it is a long story. I bought Carbonite HomePlus because one thing it does is make a mirror image of the HD to an external HD (which is a USB3 in my case). The docs say that it will take several hours to make the initial mirror image. It was taking a very long time. It was getting < 1% of the CPU and usually < 1% of the disc bandwidth. It was usually 0.1-0.2 MB/sec. Sometimes it would jump up to a few MB/sec and sometimes to 20-25 MB/sec. It was going to take several days at this rate, and I have only 300GB on the drive. I talked to Carbonite tier 1 and tier 2 tech support a few times, and some said that it just takes that long and others said that something is wrong. It finally finished after almost 6.5 days (155 hours). I think this is unacceptable because the mirror image is useless until it gets a complete image. (I had to reformat the external HD to do it, and had wiped a Microsoft drive image in the process, thinking that it would only take a few hours to do the new one. The MS one had taken only 3 hours.)

Anyhow, they bumped me up to tier 3 support, but it took more than a week for us to find a good mutual time. By that time the initial mirror image had completed. Tier 3 said that I had way too many HD errors. He said that my HD is so bad that the minuscule amount of processing that Carbonite is doing on it (about 0.1% of its capacity) is putting too much stress on it (which I don't believe). He said that the mirror image was useless because if my HD crashed and I replaced it and restored from the mirror image, what ever is wrong would cause the new drive to crash. And if I put in another new drive after that and restored, whatever is wrong would cause it to crash. (I don't believe this either, since if I have a H crash, it will be a head crash or other physical breakdown.) He wanted me to quit using the mirror image feature and refund part of my money and downgrade me to carbonite w/o the mirror image. I didn't want to do that, because I didn't really understand how it could cause a replacement drive to crash. He did turn off the daily updates of the mirror image.

So Carbonite software never gave me an error message, it just took a very long time for the initial mirror image. THe tech support people were all very nice, but they told me conflicting things and things I find hard to believe. Bubba73 ^{You talkin' to me?} 23:55, 7 April 2013 (UTC)

You should talk to a different support person, since that one has no idea what he's talking about.

Did HD Tune finish scanning the disk a few hours, or did it take days? If I understand correctly, you are not actually getting an error from Carbonite, it's just running slowly. Possibilities: 1. Another program may have been trying to access other files on one of the drives during the backup, causing a lot of back-and-forth seeking which can slow everything to a crawl. 2. There are a couple of SMART parameters above that do seem to show significant degradation: "Seek Error Rate" and "Hardware ECC Recovered". Both of those could conceivably slow things down. The next time you have this problem, you could look at the data values for those parameters in real time and see if they're increasing. 3. Maybe it's the backup drive that's failing; have you checked its SMART values? 4. There could be something wrong with the USB connection causing it to fall back to USB 1 speed. -- BenRG 05:32, 8 April 2013 (UTC)

HTTP Cookie

When a website is visited generally a cookie file is created at the server side then sent and stored in the client side.Is it possible for a human user to manually decrypt this cookie file with or without the help of some software tool.If so how?Will some Wikipedian elaborately expain this by giving an example? — Preceding unsigned comment added by Ichgab (talk • contribs) 07:17, 7 April 2013 (UTC)

You can view the contents of a cookie easily; most browsers have a simple function to do that. In Firefox it's rightclick -> viewPageInfo -> security -> viewCookies. But most cookies you'll see have a value that's just some random letters (or maybe a few labelled sequences of random letters). This isn't encrypted, so there's no decrypting to be done. Mostly cookies are like railway tickets: they have some numbers in them, and the important one may be a ticket number - but (unless you're a serious trainspotter) all the numbers are, from your perspective, essentially inscrutable. -- Finlay McWalterჷTalk 08:31, 7 April 2013 (UTC)

Not just one cookie either. Wikipedia has 14 cookies on my PC.--Shantavira|^{feed me} 14:36, 7 April 2013 (UTC)

Cookies aren't encrypted, although the values inside the cookie can be encrypted. For example, on the web site I work with, we store a session ID in the cookie, but encrypt it for security purposes. If the session ID wasn't encrypted, it may be possible for a hacker to hijack someone else's session. A Quest For Knowledge (talk) 14:50, 7 April 2013 (UTC)

android ≠ / = android

I bought my first android tablet (a cheap Ainol Novo7 Mars), that has a lot of chinese programs among with english ones and does not have my native language installed. It has now 4.0.3 system from manufacture's update. Can I install another android 4.0.3 or 4.0.4 system in it or even higher like 4.1.x or 4.2.x?--RicHard-59 (talk) 12:50, 7 April 2013 (UTC)

This video shows how to change the OS interface to English. Mostly you can only get OS updates from the manufacturer; the Android distribution from Google is intended for manufacturers, who configure it for their specific machine and add in stuff like device drivers for that particular platform. In a few cases you can get homebrew builds from enthusiasts, working to replicate the manufacturer's work. Looking at the NOVO7 article, it links to two CyanogenMod based firmware builds for the NOVO7; you should look into those, or in general check the CyanogenMod forums. -- Finlay McWalterჷTalk 13:12, 7 April 2013 (UTC)

I have the slightly older Novo 7 Basic and got useful advice from the forums at tabletrepublic. Their Novo 7 Mars forum doesn't have much content at present but would be a good place to ask for help. Flash my android is a forum with slightly more content, and has details of a 4.0.4 rom. I have no idea myself how good this rom might be.-gadfium 23:38, 7 April 2013 (UTC)

How old to learn Java?

When is the general upper limit, age-wise, for learning how to program in various code languages such as Java? Neuroplasticity degrades with age, so learning how to do it younger, I would image, would be best. If someone is in there mid-twenties, is it too late to learn how to program in Java well enough to make small Android apps? Acceptable (talk) 15:17, 7 April 2013 (UTC)

People tend not to go on degree courses once they get past 90 so I'd say somewhere around there is where one should perhaps give it a second thought. Dmcq (talk) 16:45, 7 April 2013 (UTC)

It’d probably be best to learn as much as early as you can, but there’s no particular reason to not learn it later in life if you have an interest. One might rethink learning Java™ for some other language that’ll have a better future, though. :p ¦ Reisio (talk) 17:30, 7 April 2013 (UTC)

I'm fairly sure that I pick up new programming languages now as fast as when I was 16 or 25 (and I have a lot more "experience" now ;-). I think Dmcq is spot-on. As long as you can hit the right key, you should be able to learn to program. --Stephan Schulz (talk) 19:56, 7 April 2013 (UTC)

There is a big difference, I might add, from learning Java as one of many programming languages you already know and learning Java as your first programming language. If you already more or less know how to program, especially OO languages, then adding Java can be done practically at any age over the course of a few weekends. If you're learning to program Java from nothing, that involves quite a lot more brain-stretching. In any case, I don't think mid-twenties is any kind of cutoff date whatsoever. I know people who have learned significantly new computing skills well into their 40s and I really don't see why there should be any significant cutoff well until one is very old indeed. To make an analogy, there are many people who learn how to play piano very late in life. Do any of them become brilliant virtuosos? Probably very few. But there is quite a lot of gulf between "enjoys playing piano" and "plays sold-out concert halls." I doubt someone coming to programming very late in life is likely to be the next genius programmer, but that doesn't mean they can't make apps or many other things. --Mr.98 (talk) 20:08, 7 April 2013 (UTC)

Linux Firefox download of .webm vs .flv

I downloaded a video from youtube using the plugin Flash Video Downloader, and selected the .webm file. The 306MB file took about three minutes to download. Just for a laugh, I decided to download the .flv version of the file and the 262MB took 29 minutes. Why should this take 10 times as long? --TrogWoolley (talk) 15:50, 7 April 2013 (UTC)

I'm not familiar with that particular extension (and the reviews for it don't persuade me that installing it is a good idea), but that performance hasn't been my experience, with similar extensions. FLVs, from YouTube or elsewhere, download many times faster than real-time for me, on a normal ADSL connection. It may be that your particular extension (documentation for which I failed to find) has code to deliberately choke FLV download speeds so it resembles the pattern of an actual Flash player (so as to thwart anti-download measures some cites may implement). If that's the cause, one would hope there was an option to disable that behaviour for sites, like YouTube, that don't care. -- Finlay McWalterჷTalk 16:04, 7 April 2013 (UTC)

You’d probably already watched the .webm version, and therefore already had it all cached somewhere, so the download was more of a move. ¦ Reisio (talk) 17:32, 7 April 2013 (UTC)

In my experience, different display resolutions will download at different speeds from YouTube. I don't know anything about the webm format, but what might be happening is that the FLV is at a smaller resolution than the webm file, which will download slower. With my downloading plugin for Firefox, when I choose 240p, I get ~50KB/sec. With 480p I get 150+ KB/sec, and with 720p I can get over 1MB/sec. -- 143.85.199.242 (talk) 15:43, 8 April 2013 (UTC)