Input/output error when copying files to Fedora Live CD

kenneho · 12-21-2010, 06:24 AM

Hi all,

I booted my Fedora 13 live CD on my Dell server, and configured networking and SSHd. On my desktop I logged into the live cd and started copying over a big file (1.5 GB) (i.e. copying from the desktop computer to the server). After copying about half the fil, the download fails with an error message about the filesystem being read-only.

I've seen this exact same behavior on both i386 and x86_64 of the same live CD, but don't know why it's happening. I've also had the same issue when copying small files. In /var/log/messages these messages are repeated many times:

Code:

Dec 20 12:32:23 localhost kernel: Buffer I/O error on device dm-0, logical block 684075
Dec 20 12:32:23 localhost kernel: lost page write due to I/O error on dm-0
Dec 20 12:32:23 localhost kernel: Buffer I/O error on device dm-0, logical block 685598
Dec 20 12:32:23 localhost kernel: lost page write due to I/O error on dm-0
Dec 20 12:32:23 localhost kernel: Buffer I/O error on device dm-0, logical block 685609
Dec 20 12:32:23 localhost kernel: lost page write due to I/O error on dm-0
Dec 20 12:32:23 localhost kernel: Buffer I/O error on device dm-0, logical block 684147
Dec 20 12:32:23 localhost kernel: lost page write due to I/O error on dm-0

Does anyone know what may be causing this? It makes it impossible to use the Fedora Live CD for the task at hand the way it is now, so any advice is appreciated.

- kenneho

PS. I posted the same issue on fedoraforum.org, but since I didn't get any replies I'm posting here too.

JoshyJ · 12-21-2010, 06:33 AM

Files cannot be stored onto the LiveCD as it is a read-only filesystem as it stated.

You will have to mount another filesystem which you can write to like a harddrive or flashdrive.

kenneho · 01-05-2011, 05:53 AM

Quote:

Originally Posted by JoshyJ

Files cannot be stored onto the LiveCD as it is a read-only filesystem as it stated.

You will have to mount another filesystem which you can write to like a harddrive or flashdrive.

Thanks for your reply. On the Fedora web site (http://fedoraproject.org/wiki/FedoraLiveCD), however, it is stated that current features include "Read-write rootfs so it's possible to install software while the livecd is running". So it seems like it should be possible to copy over files..

TobiSGD · 01-05-2011, 06:00 AM

You can install software to the live-CD, but this is not a permanent install. The files from the installed software are stored in RAM and will be lost when you power off or reboot the computer.
This is the same for all files you store in the live system, except files that are stored to a mounted disk. If the file is to big to fit on the virtual filesystem in RAM you will get that error.

kenneho · 01-06-2011, 03:42 AM

Quote:

Originally Posted by TobiSGD

You can install software to the live-CD, but this is not a permanent install. The files from the installed software are stored in RAM and will be lost when you power off or reboot the computer.
This is the same for all files you store in the live system, except files that are stored to a mounted disk. If the file is to big to fit on the virtual filesystem in RAM you will get that error.

Thanks for the input. I'm using the live-CD to perform a disaster recovery test, and need to install the backup agent to restore the files. Basically, this is the plan:
* Boot the live CD
* Mount the local disk, create the partitions etc
* Install the backup software client on the live-CD, and restore file systems to the local disk
* Create boot, and restart

The problem is that the live-CD fails when trying to copy over the backup software client, which is 1.5 GB in size. The RAM on the server is about 64GB, and I'm assuming that I should be able to fill up all the RAM with files if needed. As shown in the output below, it seems like the root partition is read-write, and thus the backup software client install should work:

Code:

[root@localhost ~]# mount
/dev/mapper/live-rw on / type ext4 (rw,noatime)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
tmpfs on /dev/shm type tmpfs (rw,rootcontext="system_u:object_r:tmpfs_t:s0")
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
/dev/sr0 on /mnt/live type iso9660 (ro)
varcacheyum on /var/cache/yum type tmpfs (rw,mode=0755,rootcontext="system_u:object_r:rpm_var_cache_t:s0")
/tmp on /tmp type tmpfs (rw,rootcontext="system_u:object_r:tmp_t:s0")
vartmp on /var/tmp type tmpfs (rw,rootcontext="system_u:object_r:tmp_t:s0")
gvfs-fuse-daemon on /home/liveuser/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=liveuser)

But for some reason it fails, so I'm going to go with JoshyJ's suggestion and store the backup client on a harddrive. I'm going to try and create a temporary partition on the the local disk, install/copy the agent there, and see if that works. But anyways I'm really puzzled as to why the live-CD fails when I'm trying to create files there...

- kenneho

jschiwal · 01-06-2011, 03:58 AM

Is the live cd a 32bit distro or 64bit distro?
While the server may have 64GB of memory, if you boot up a 32 bit distro, only 3 gb can be accesses. Subtract the area of memory where devices are mapped, and the memory used running the system. That could easily leave less than 1.5 GB available.

kenneho · 01-06-2011, 04:39 AM

Quote:

Originally Posted by jschiwal

Is the live cd a 32bit distro or 64bit distro?
While the server may have 64GB of memory, if you boot up a 32 bit distro, only 3 gb can be accesses. Subtract the area of memory where devices are mapped, and the memory used running the system. That could easily leave less than 1.5 GB available.

It's a 64-bit Fedora live-CD, and as you can see the entire memory is available to linux:

Code:

[root@localhost mnt]# free -m
             total       used       free     shared    buffers     cached
Mem:         64621       2541      62079          0        140        933
-/+ buffers/cache:       1467      63153
Swap:            0          0          0

So I have a read write file system, and over 60 GB of free memory, and still I get I/O error when trying to put files on the file system. Very strange... And ideas what could be the cause?