USB disk only work fo a while

[paros]

I have Lacie Network Space vs2 and trying to use a USB disk (powered by the USB cable) as a backup disk.
I have created a few CRON jobs and using mirror backup option.

THe problem is that the USB disk disappear after a while and only come back if I disconnect it to the Network Space.
I have tried to use NTFS, FAT32 and EXT4 format options.

I have also tried to remove spin down.

The disk is connected on the front of the Network Space.

What can be the problem?

[Jocko]

Hi paros,

you can see the dmesg output if there are some issues with the usb device sdb( or sdc,... several remounts).

Maybe there is also a power issue if you have a big disk