DISCUSSION: External USB or firewire drives

This thread is to discuss the article titled: External USB or firewire drives

A statement made in the article is not, strictly speaking, true. I'm nitpicking a bit, of course...


Statement:

Fact: Fat32 filesystem instead of ext3 or ReiserFs or any other makes your drive portable and compatible with any operating system because both Linux and Windows read and write fat32. (Linux only reads NTFS reliably and the writing is shaky at best. As for Windows, it doesn't read or write any unix filesystem)





Correction:

Fact: Fat32 filesystem instead of ext3 or ReiserFs or any other makes your drive portable and compatible with any operating system because both Linux and Windows read and write fat32. Bear in mind, that fat32 filesystems do not support 'chmod' for file permissions in linux. File permissions are set the same for all files using the umask variable in the file located at "/etc/fstab" (The file system table for linux). This means that fat32 fcan be shaky as linux root filesystems, although it is definitely possible thru a compressed cloop image file in a fat32 filesystem, like knoppix can do. (Linux reads NTFS reliably but the writing is shaky at best and disabled by default. However, the captive-ntfs tool at http://www.jankratochvil.net/project/captive/ has been reported to work well with NTFS . As for Windows, it doesn't NATIVELY read or write any unix filesystem. There are tools that read linux ext2/3 partitions, like extfs at http://uranus.it.swin.edu.au/~jn/linux/explore2fs.htm , and there are write drivers for ext fs's for windows as well like in http://winext2fsd.sourceforge.net/, but you have to download them. Writing ext fs's in windows is unreliable also, but reading works just fine).

Hope this thread isn't old and thus will never be seen.

Is external USB drives shareable? I've tried with both Xandros and Linspire and I get the "you don't have permission" error from my WinXP machine when I try to access it on the network.

Fact: Linux partitioning tools, Command line or graphical, like DiskDrake are wonderful but THEY DO NOT LIKE EXTERNAL DRIVES OF ANY KIND when it comes to formating. Just remember that. So... that means do not try to partition your external drive with them. It most probably won't work and you'll get errors.

These are bad news!
I was considering buying an external hard disk; I need some extra space for data (a couple of partitions) and I'd like to backup my /home partition (preserving permisions, etc): another partition. And I need it EXTERNAL.
Does anyone know how to do this under linux?
I mean, is it absolutely impossible partitioning+making filesystems without errors in linux?
how true are the comments above quoted?
TIA, please give me hope...

Regards

this is really a good thread for linux newbies like me.
now i've get my USB drive mounted.

but i've a question here:
anything we can do so that when we plug in the USB drive, it is detected and automaticly mounted? (and its icon automatic appear on desktop)
just like what happen when we insert a CD in the CDrom.

thanks.

I frequently need to back up BIG files, some as large as 20 Gb, and files that size won't go on a fat 32 drive. Is Partition Magic reliable for formatting external hard drives ext3?

I bought myself a 256 MB Astone USB2 key, and when I first plugged it into SuSE, it was presented as having four partitions.
I did a bit of research, and found this is pretty much standard ?
Anyway, I didn't see the point using four of them, so I partitioned it using the linux fdisk, and that worked fine.
During the partitioning process, I had it list the ones it could see, and apparently they where not only "out of order" (ie not 1,2,3,4), it said it the partition sizes didn't match their parameters.

I have used the key since, formated fat32, single partition, and it's quite happy so far

I'm curious as to why using a linux partition programme on a usb key is considered bad ?

Not to play the devils advocate, but I have succesfully formatted my usb drive under Slackware 10.1 using mkfs. If you want fat32 use:

mkdosfs /dev/sdX -c -F 32 -I -v

The -c and -v can be left off (respectively) if you don't want it to check for bad blocks and be verbose during the entire process.

Granted you should edit the partition with cfdisk or fdisk first. Also, the big gotcha is that some users forget to unmount the drive before formatting. Just thought I'd throw my 2 cents out there.

Part of what brought me here is that I had to reformat the hardrive in my Rio Karma (DAP), and I got tired of Windoze hanging around 50% for an ungodly amount of time. At least in Linux I know the job will be done right and I don't have to worry once I tell it what to do.

Just for the lazy ones here (like me )):

No need to reboot, just type

mount -a

that will reread /etc/fstab and mount any unmounted devices (though I don't know about the icons in the GUI)...

I have an interesting situation in that I have a Linksys Network Storage Link which connects to two USB drives that I use for home storage. The linksys website stated that its OS was a linux derivative so I plugged the USB drives into my laptop when it was running Fedora and to my surprise both drives automounted and appeared on my desktop. I moved the drives back to my Linksys device and restarted it and went on my merry way copying, moving and deleting files. When I experienced a problem with timeouts while moving a 40Gig backup file it dawned on me to connect the drives back to my Fedora and just drag and drop them so I did but when I moved the drives back to the Linksys I no longer have the rights to r or w. I looked at the permissions via the Linksys and it displays that I have the correct permissions. I tried changing permissions and it acts like it is working but when I come back the permissions are back to what they were. So I moved the drives back to my Fedora and tried to change permissions and the error I get is 'Read Only Drive'. The really funny thing is that when connected to the Linksys I have permission to r+w the files I moved, it is the files I didn't move that I seem to have lost the permissions on. Any ideas on how to correct this short of letting the Linksys reformat the drives?

Maybe I got lucky, but I succesfully partitioned two USB2 external HDD using sfdisk, and then formated them using mkfs :
- I plug the disk in an USB2 slot
- it is detected as /dev/sda
- # sfdisk /dev/sda
- you ready to roll

could it be because they aren't "true" external drives, but rather IDE drives in an external USB2 rack ? I thought it would change nothing. Or is my software simply more recent ?

While searching for a problem I have with mkdosfs, I came across this thread (and rather indirectly at that..). I noticed a number of problems with the article and I happen to be in a contribute mood (whatever that means) so here is where I know for a fact things work and don't work.

I have two working scratch systems that run entirely off usb, on any pc-compatible system with a either usb 2.0 (which as far as I have seen generally support usb-boot..no comment for award bioses) or a usb 1.1 system with a cdrom drive.
I only have usb 1.1 systems that don't boot usb.

1) As noted by the article, many graphical partitioners donot like USB. With Partition Expert 2003 (maybe it was Partiion magick, I confused the two..sorry), this is certainly true. But with QT-Parted, this graphical partition has no trouble whatsoever in any way and supports vfat and ntfs filesystem installs. System Rescue CD is a safe approach to using QT-Parted, no worries about RPM's, dependencies, or scratch installs. Just burn System Rescue CD and you can almost go straight into qtparted.

2) That aside, the way I have the systems setup is as follows:
root partition ( / ): ext3 - ext3 takes a little more space, but USB Devices unplug easily. if you unplug your OS you will most certainly screw up something. Ext2 will give hell on every one of those problems, while ext3 makes "live unplug recovery" quick and clean.
Shared Directory( /home/share ): A common practice of mine, in which all files here are considered permissionless. This will be vfat (fat 16, which fits better on smaller usb-sticks, if you have say...2-gigs or more for this partition, you can safely make it fat32 instead)

3) In these partitions, I give unique Labels, for the USB-device:
root partition ( / ): 635SAC_/
This label is simply a serial number for the usb-device and the the _/ to designate the root partition.
This is good for when there are more usb-devices plugged in, how does the system know which device, or even system you want? Well of course a unique label would work. This will prevent having two usb-sticks of the same system and mounting the wrong one (or even worse, different parts of each)
Shared Directory ( /home/share ): mkdosfs has a nice little command called -n Follow this with an at most 11-character system name (like: 635SAC_/hom) for the same purposes as above. WARNING: This is one of the problems I need to look up, the linux system doesn't seem to always see this label and occasionally does not mount. In addition I had to format the vfat system about 20 times to make the label stick.
* This Shared Directory can be accessible from Windows as well as linux, giving you freedom to move files if you don't want to boot to your USB-system and have, say a readily available Windows system around.

4) Moving on, preparing to boot! Not so easy with the stock linux-kernel. (needs 1-improvement in my opinion and thats root=LABEL=635SAC_/)
First, you need the /etc/fstab file, as already noted, LABELS are best choice here.
Where you might have /dev/sda2 use LABEL=635SAC_/.
Here is one of mine:

LABEL=635SAC_/       /                    ext3       defaults                       1 1
LABEL=635SAC_/home   /home                ext3       defaults                       1 2
LABEL=635SAC_vfat    /home/share          vfat       users,gid=users,umask=0        0 0
tmpfs                /tmp                 tmpfs      size=128m,mode=1777            0 0

Notes on above:
Windows XP has a problem with USB-Memory Sticks and probably with USB-HardDrives. The problem is this: The first partition it finds, it assumes its vfat or ntfs, otherwise it says your drive needs to be formatted. The system will ignore every single other partition present, including any windows partitions. For this reason, make the first partition vfat if you intend to have a windows partition. (ie: make /dev/sda1 vfat).
Also notice the /tmp mount. That is useful if you have a small usb-memory stick that cannot hold much. This gives you 128 megabytes of room in the /tmp directory (at the potential cost of using 128 mb of your memory )
A final problem is the biggest one. SWAP??? Well if you have got the space for a swap, make it so. Otherwise it can be left alone with hopes you have enough system memory. With Linux that is rarely a problem with 512mb or above..unless you watch lotsa movies or work with art. Anything less, there may be trouble.

5) Now we can really boot? Or can we?
well if you've got usb-boot your almost done.
with usb-boot, you can just put grub on the usb-system.
After that, you have to pass root=/dev/sda2 AND rootdelay=6. I find 6 to be the fastest safe wait time. The system has to wait on the usb to say hello, before it attempts to mount it. if you forget rootdelay or set it too short, your system will not boot.
Secondly, you may have to get an initrd or constantly change the root=/dev/sda2 option depending on how may usb-devices are plugged in and which gets assigned in what order. An initrd my allow you to pass an option such as root=LABEL=635SAC_/ and thus have no more problems. I am still working on learning how to mkinitrd or Make an Initrd. Documentation this far seems to suck and those that don't seem to depend on a certain dist with certain dependencies...so much for my SCRATCH system!!
If you in my boot, you have to boot to a cdrom device. This gets fun. I already had a discussion about this in LinuxQuestions so go here for the help on this: http://www.linuxquestions.org/questi...hreadid=375493
Same problems with root=/dev/sd?? still exist with the cdrom.

I prefer grub over lilo and by all means syslinux (as syslinux requires the nasty windows partitions, which in my opinion makes it a little anti-linux), as grub allows you to change settings on the fly, getting around many of the boot-time problems and tweaks one might need to get a USB system ti boot, solely from the usb and/or cdrom. Nothing wrong with lilo other than the fact that last time I tried it, I had to not only re-edit the config from a running system, but also recompile parts of the thing just to get it to boot! That will be hell if you can't get to your USB system, because you have to first get on it so you can fix your problem about not getting on it!! And thus, I conclude, the strangely maintained grub is the choice for USB systems.

6) Thats all, unless I missed something is this book of a post.

Hi Yearp. Wow. That's a lot to digest but very thorough. Thank you kindly for it I know I'll be absorbing it...

Originally posted by Yerp ... 2) ... if you unplug your OS you will most certainly screw up something. Ext2 will give hell on every one of those problems, while ext3 makes "live unplug recovery" quick and clean. ... 3) ... This is good for when there are more usb-devices plugged in, how does the system know which device, or even system you want? ...

Just as a matter of interest, why don't you use "udev"? See http://gd.tuwien.ac.at/linuxcommand....ges/udev8.html
If I understood correctly what you mean this should hopefully solve (part of) your problems... .

I am using SuSE 9.3 along with Windows XP on a dual partion, recently I bought an external usb hard drive. Yesterday I partitioned USB drive in Linux with ext3 fs, while partitioning it gave me a warning that it is creating UUID for the drive and sometimes it is dangerous, but I ignored it. But now I am unable to boot to linux os. I don't know what went worng. Guys please help me.

Thanks