Author Topic: Best way to download iso images? Getting faulity images.  (Read 1138 times)

BurungHantu

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Best way to download iso images? Getting faulity images.
« on: April 05, 2010, 01:02:06 AM »
 ??? I have been discovering lately that possibly 'all' the images I've downloaded are faulty? I am not sure th reason. I used one download manager that breaks the images into threads of up to 10 to make it faster or ease the load etc.

I have tried directly with the browser. Various.

I tried another downloader called 'Fatrat'.

All my operating systems are linux based. The one windows machine I had, just gave up the ghost therefore I needed a machine up fast to work with.

Unfortunately, all my iso's when tested under the check media 'fail'.

I am using USB. I can't use DVD/CD due to media and hardware problems. Media where I am in the world is just suspect. It is poor quality.

Burners where I am also do not have but two modes of burning. TAO and SAO. No DAO. I have heard now DAO may be replaced with MAO? Whatever. You won't find it on a Burner in this country and I have been unable currently to order from abroad at the moment.

I have tried several ways to test this. I have two USB drives.

I have downloaded all the isos from the same mirror. Put the same one on both USB drives. (I am trying to see if the USB drives are at fault. Given the poor media quality here. I wouldn't be surprised. However, I usually thought that USB drives simply failed if they were faulty. For example some I bought were fakes of namebrandes and it was impossible to install a Linux Live iso on them. They all broke the 1st time. In about 5min of opening the pack and using them. But maybe it is still a problem with the USB media. Any suggestions to test them would be welcome.)

Now, I have downloaded the same iso from different mirrors. Same result. On one occasion I found that the same ISO wouldn't even boot. Gave an error and dropped me into a shell.

That was when I began to suspect that the iso was not downloading well or properly.

SO far not one ISO though they will boot into Livemode and look well and seem to behave well, has passed the media test?

In fact the media test never makes it past 1%??

Any ideas?

What is the best way to get a stable download? Is it possible the USB drives can still be faulty despite the fact they work or seem to? Is the problem the manner in which the USB Live system is installed? Unetbootin?

However, the 1st USB drive I got, I installed two Linux systems on the computer that just gave up the GHoST.
Those system were quite good and stable. PClinuxOS and the other was even 64bit. They worked well. But that doesn't mean that the performance may not have deteriorated with that USB.

I always carry it around so I've got a Live Linux with me. While I was trapped for the last two months in another country just recently I had my trust little USB with PClin on it so when I went to netbars... I could have a bit of privacy if needed.

I welcome any suggestions to solve my problem...


Online Old-Polack

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Re: Best way to download iso images? Getting faulity images.
« Reply #1 on: April 05, 2010, 01:26:00 AM »
BurungHantu:

Two items. First, there is no MAO mode. That was supposed to be somebody's idea of a joke, since you said you were in China. A word play on DOA, as in the name being replaced by one honoring Chairman MAO. Some of us here have a strange sense of humor. It wasn't meant to be taken seriously. Stick around and you'll get used to some of our silliness. ;D

On a serious note, if you are getting that many bad downloads, check your RAM sticks by running memtest86, for at least an hour. If errors result, and you have more than one stick of RAM, test each individually. Remove any stick that shows errors, then try again to download the image. With bad RAM, the download source could be good, but the file gets corrupted when being written to the drive disk. Also things like md5sum errors occur, even when the actual file is correct. Bad ram can cause all sorts of odd hard to troubleshoot symptoms. It really is critical that one get the best quality RAM one can afford.
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Offline marian

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Re: Best way to download iso images? Getting faulity images.
« Reply #2 on: April 05, 2010, 02:37:29 AM »
You should check your iso with md5sum first. If there are not errors then your download is ok and the problem is elsewhere.
It can be the RAM as old-polack suggested.
My friend gave me a few ISOs and when I checked them (md5sum) all had errors.
Then he find out that one of his RAMs were faulty.
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BurungHantu

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Re: Best way to download iso images? Getting faulity images.
« Reply #3 on: April 06, 2010, 06:15:13 AM »
Last I recalled, checking MD5sum was a complicated formula. SO I never have bothered. I usually in the case of some distros that have it on the menu, let it check it and I have sometiems found the check to show the md5sum as bad. But not so consitantly.

If someone can put a step by step procedure that isn't a pain in the neck. I'll surely do it. What I browsed on google for doing it, a long while ago, wasn't something that looked easy.

I have checked the ram several times. It is a new computer, this little one here. SO sometimes I've heard the ram modules can be bad right out the box. Everytime the test reveals no errors.

SO I guess, I must consider that the PClin media test saying don't use this media, is 'not' talking at all about the ISO, but it is referring to these crap USB drives.

Typical of what's sold here. The computer that died on me, has two Linux installs from one of these two usb drives. When that was brand new! Those systems, one of which was PClin LXDE that I set up myself with the desktops I wanted on them etc, has worked very well with no issues. (Yet by the way, that same image when put on these USB, not says don't use this media when tested! But it's the same image! I saved it to my portable HDD)

The other distro, also worked well and it was first time I tried a 64bit system so expected to run into problems but I really didn't.

Now that old USB along with one I just bought, seems to be neck and neck for returning a do not use this media when using the PClin media check tool on the iso.

SO anyone have a clue how to test a SSD drive/USB drive? I usually find they just give up the ghost when they don't work. (As with several fakes I bought and tried to run livemode from. They just totally crashed. Then you can do nothing with them! Not even reformat! I've been returning them and asking my money back. If it says it's a namebrand why is it crashing?)

Now another idea I've got but haven't had time to go to the computer store and try, is that I also understand that a SD card can be used for this? If you reformat it?

Since at the 'moment', I have had better success, I am going out on a limb with this, with SD, MMC and other memory cards here. That maybe I'd be better off buying a SD card of suitable capacity, both the USB drives are 8gb (Like in the instance of remastering with a lot of programs added) and reformatting them and trying to boot from them instead?

I only go out on a limb with that suggestion because I have bought SD/MMC/ cards here for cameras and mobile phones and haven't had them crash. Though I know one person out of many who did have a 'bad' memory card or so they were told by the Nokia center which said that was why it was 'confusing' her phone. Then again, later that 'phone' crashed big time.

I've found too often here don't ask the professionals because they really aren't. They may often do more damage than you may yourself...




Offline Was_Just19

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Re: Best way to download iso images? Getting faulity images.
« Reply #4 on: April 06, 2010, 06:37:04 AM »
To get the MD5Sum for any file, in a terminal type

md5sum <filename>       <enter>

it shoud return the number in the terminal which you can use to compare with the one issued with the ISO.

Offline sling-shot

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Re: Best way to download iso images? Getting faulity images.
« Reply #5 on: April 06, 2010, 10:35:50 AM »
Consider 2 things.
1. Avoid using multi-threaded download managers for downloading large .iso images. Use the command line 'wget' after extracting the exact address from your favourite download manager. It works the best.

2. May be your USB drive itself is defective. I had a Transcend 4 GB unit in which only files larger than 400 MB turned bad. Gave back for replacement now things are fine.

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Offline kjpetrie

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Re: Best way to download iso images? Getting faulity images.
« Reply #6 on: April 06, 2010, 01:34:44 PM »
I thought SAO (Session at Once) was just the correct name for what is normally called DAO (Disc at Once). Is that not correct?

Secondly, does media test work on a USB stick? Maybe it does - I don't know. You can check the md5sum on the USB matches that of the extracted files on your hard drive using JohnBoy's instructions. If they match your USB stick is OK.

If you loop mount the ISO (man mount for details) you can also check the md5sums of the files on the ISO.

All this should tell you where the problem is occurring.
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BurungHantu

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Re: Best way to download iso images? Getting faulity images.
« Reply #7 on: April 07, 2010, 04:19:28 AM »
To JohnBoy, thank you. I started linux in 2006, I remember then looking up how to do md5sum and it wasn't so simple. I looked it up again however because I know you guys are giving me good suggestions and I did find that it is as simple as you stated...

Results: 3 out of 5 with OPERA Browser. Maybe I should say 3 out of 4 but I tried two times with an image that is 2.1gb. This iso does not check out every time. I now have 3 iso images that match md5sum and will check the USB as suggested to see that once Unetbootin puts it over is it not the same?

Where I live, a faulty USB is practically a fact of life. Getting one that works is more like a pleasant surprise in the scheme of things.

Until I really have some way to order products from overseas this is an ordeal I face on a regular basis any time I just want to do something simple. Then I can struggle with it for hours.

Mostly because of hardware.

My guess is it was probably two problems. Some iso's were not good. Everything I downloaded from firefox was not. As noted the multi-stream downloader wasn't effective either, and FATRAT? It didn't
do multi-stream but seems it didn't do well either. In the old days before I got into using downloaders
I did usually just use Opera. (It's built in downloader, can do bittorrents as too, was always hassle free for me.)

uh, wget? Just extract the location and put it in wget you say? Will have a try.

Sling-shot, you are therefore recommending 'not' to use any GUI interfaces of wget? Any reason?

TO the other person, about SAO(Session at once), TAO (Track at once), and DAO (Disk at once). I wanted to know why I could never get a good image and one particular iso of a Linux Distro I had very strongly stressed in their burning instructions do not use anything but DAO to write the compressed format. SO I thought there 'must' be a difference and I looked it up.

There is a difference. SAO does happen not to write/close the optical disc to till the end like DAO. But there is a difference and other than iso, what is DAO good for? It's good for backing up DVDs! Now where I live. They 'pretend' they're cracking down on this sort of thing and the way to do that is to supposedly make sure the 'every day joe' can't get their hands on hardware that can burn in this way.

I spent a whole day once in what passes for the computer city center here and tested every DVD writer I could get my hands on looking for 1 with DAO. These were big units that go in Desktops cause they only have this 1 IBM clone slim dvdwriter here, I've never seen another brand anywhere. You can put them in a box and run them as USB and they don't cost much. Rather cheap even the good ones. (Now if I lived in some place like Shanghai, or Beijing, this probably wouldn't be a problem. Someone would have one for a price. However, I hate big cities and I wouldn't live in one of those places if you paid me and they're literally on the other side of the country from where I am.)

When I arrived in this country. With my 'old' Desktop at the time. I had a 'rare' thing! A computer with a DVD writer in it! No joke. At that time 256ram! Was a lot of RAM and if you wanted anything with 512
you were gonna pay dearly for it. To get something with a DVD writer in it? OUCH! You were really gonna pay an arm and leg.

Then good old VISTA happened. The memory market just dropped and now you can buy 1gb of DDR2 for like around 9bucks or so(My recent dead machine, has DDR1 and just getting myself a nice 1gb card of it was highway robbery!). They started putting more memory in computers but even now...

What you'd get for memory on a mid-level computer in USA, is not what you would get here. I hear it's pretty easy now to get something for a reasonable price in US with 4gb of ram. The 4g ram computers are just coming here... and 2gb of ram is still the norm and there are still lots of DDR2 and the DDR3's are slow coming to the shelf so to speak.

Always a step behind.

I can't recall all the info, but you're best off burning DAO for an iso image. I just looked up all that stuff cause I wanted to know what was DAO and could I burn an image well without it. It's sorta of a chance thing. The image may come out well, like for example, the massive number of uncompressed pirated Winduds crap they sell here.

But an iso? Well maybe but maybe not. So unable to get a Burner with DAO I abandoned the burning process. Not to mention, the optical media here, DVD's are just not up to snuff. I literally hesitate to burn on a CD here, they're usually that bad and just a waste of time and money.

A coworker and I, literally went to HP repair to buy their CDs and DVDs because they were the only ones that worked consistently, at rather extotionate prices I may add.

So, SAO when you google it is definately something different in the writing scheme than DAO.

To Johnboy, some basic commands on using wget from command line????

Has anyone tried using Memory cards and a usb cardreader for booting from? I just toss this idea out because probably the only media I've bought here that does seem to work a bit more consistently, are memory cards. They don't seem to have the crash rate of USB drives but I am not the only one I've witnessed with crashing usb drives. A lot of people have them.

But I don't hear too many complaints from those with mobile phones and media cards... but who knows,
for this purpose, maybe they'll crash too... hahaa.

Offline Was_Just19

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Re: Best way to download iso images? Getting faulity images.
« Reply #8 on: April 07, 2010, 04:48:43 AM »
Quote from: BurungHantu
To JohnBoy, thank you. I started linux in 2006, I remember then looking up how to do md5sum and it wasn't so simple. I looked it up again however because I know you guys are giving me good suggestions and I did find that it is as simple as you stated...

I am glad you have that part sorted at least.   ;)

On the matter of downloading .......  I use Kget exclusively here as it integrates into KDE rather well.


You might have a look at the manual page for wget for more information on that, either in a terminal as
man wget
or in Konqueror browser as
man:wget
You could also read
info:wget
Those should help you figure it out.

In its simplest form you just type wget followed by the location of the file you wish to d/load.
Here is an example of wget d/loading the MD5sum file for the Openbox PCLOS ISO that is on the Heanet mirror. I hope this gives you an idea of what to expect. The d/loaded file is dropped into my user's Home .....  at   /home/user/<d/loaded file>

Code: [Select]
[user@Dell ~]$ wget ftp://ftp.heanet.ie/pub/pclinuxos/live-cd/english/preview/pclinuxos-openbox-2010-beta.md5sum
--2010-04-07 11:55:27--  ftp://ftp.heanet.ie/pub/pclinuxos/live-cd/english/preview/pclinuxos-openbox-2010-beta.md5sum
           => `pclinuxos-openbox-2010-beta.md5sum.1'
Resolving ftp.heanet.ie (ftp.heanet.ie)... 193.1.193.64, 2001:770:18:aa40::c101:c140
Connecting to ftp.heanet.ie (ftp.heanet.ie)|193.1.193.64|:21... connected.
Logging in as anonymous ... Logged in!
==> SYST ... done.    ==> PWD ... done.
==> TYPE I ... done.  ==> CWD (1) /pub/pclinuxos/live-cd/english/preview ... done.
==> SIZE pclinuxos-openbox-2010-beta.md5sum ... 66
==> PASV ... done.    ==> RETR pclinuxos-openbox-2010-beta.md5sum ... done.
Length: 66 (unauthoritative)

100%[========================================================================================================================>] 66          --.-K/s   in 0s

2010-04-07 11:55:28 (1.62 MB/s) - `pclinuxos-openbox-2010-beta.md5sum.1' saved [66]

[user@Dell ~]$

EDIT
Note: the above if from the second d/load of the same file and wget automatically renamed the stored file with ".1" appended rather than overwriting the first d/loaded file of the same name.


regards.
« Last Edit: April 07, 2010, 05:02:51 AM by JohnBoy »

BurungHantu

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Re: Best way to download iso images? Getting faulity images.
« Reply #9 on: April 07, 2010, 07:10:03 AM »
Thanks Johnboy!  ;) So you don't think it's necessarily a problem with a GUI. I usually use for example, Xfce or E17 as my DE's of choice. So a lot of Gnome or GTK apps fite well. The good thing about E17 is it doesn't usually care so I can grab a lot of KDE apps I'm used to.

I started Linux like many with KDE and it was more familiar because it was KDE3 at that time and well, similar to Winduds...

But I soon got 'bored' with it. It seemed too complicated to me though it still has all the options for serious point and click and it's what I plan to give my students if I can get a decent image installed and remaster it into Chinese for them.

They are taught Linux here but I do not seriously understand how or why they are 'never' shown an up to date 'modern' distro. No kidding.

But I always use Linux on my work computer in class so they're really confused because in short it doesn't look like whatever they're being shown in class.

But they like the look and some are interested in trying it.

When you say 'loop mount' the usb, can you clarify that with some examples? I profess I have no idea what you mean.  :P

Offline Was_Just19

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Re: Best way to download iso images? Getting faulity images.
« Reply #10 on: April 07, 2010, 08:41:53 AM »

When you say 'loop mount' the usb, can you clarify that with some examples? I profess I have no idea what you mean.  :P

It was not I who suggested it, but to clarify ......  it is the ISO itself that you mount and thus get access to its files, and so can do an MD5sum on them if you think some are not correct.

Quote from: kjpetrie
If you loop mount the ISO (man mount for details) you can also check the md5sums of the files on the ISO.

All this should tell you where the problem is occurring.

man:/usr/share/man/man8/mount.8.bz2

in a Konqueror location bar, and scroll to the bottom of the page for information on loop mounting.

regards.

Offline kjpetrie

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Re: Best way to download iso images? Getting faulity images.
« Reply #11 on: April 07, 2010, 03:24:28 PM »
The point is by loop mounting a known good ISO and doing md5sum on vmlinuz, inird.img and livecd.sqfs files you will get the numbers you should get from the same files on the USB key, so you can then see whether the USB is correct.
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DrDOS

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Re: Best way to download iso images? Getting faulity images.
« Reply #12 on: April 07, 2010, 05:16:35 PM »
Something not mentioned is burn speed. These are data CDs and even one incorrect bit can cause a fatal error. I only burn at 8x or less and have almost never had a problem. And most of my burns are done on an older high quality Plextor. I understand the new ones aren't so good, they seem to be trading in one their reputation.