Re: [gentoo-user] Partition of 3TB USB drive not detected

[Daniel Frey]

On 07/31/2016 06:37 AM, Jörg Schaible wrote:
> Hi,
>
> for my backups I use a 3TB USB drive (one big ext4 partition) without any
> problems. Just plug in the cable, mount it and perform the backup. The
> partition (sdi1) is detected an mountable without any problems:
>
> =============== %< ==============
> $ ls -l /dev/disk/by-id
> total 0
> lrwxrwxrwx 1 root root  9 Jul 31 13:17 ata-
> Crucial_CT500MX200SSD1_161512468483 -> ../../sda
> lrwxrwxrwx 1 root root 10 Jul 31 13:17 ata-
> Crucial_CT500MX200SSD1_161512468483-part1 -> ../../sda1
> lrwxrwxrwx 1 root root 10 Jul 31 13:17 ata-
> Crucial_CT500MX200SSD1_161512468483-part2 -> ../../sda2
> lrwxrwxrwx 1 root root 10 Jul 31 13:17 ata-
> Crucial_CT500MX200SSD1_161512468483-part3 -> ../../sda3
> lrwxrwxrwx 1 root root  9 Jul 31 13:17 ata-HL-DT-ST_DVDRAM_GH41N_K5Q9AN32423
> -> ../../sr0
> lrwxrwxrwx 1 root root  9 Jul 31 15:20 ata-ST3000DM001-1CH166_Z1F45VR9 ->
> ../../sdi
> lrwxrwxrwx 1 root root 10 Jul 31 15:20 ata-ST3000DM001-1CH166_Z1F45VR9-part1
> -> ../../sdi1
> lrwxrwxrwx 1 root root  9 Jul 31 13:17 usb-Generic-
> _Compact_Flash_20060413092100000-0:0 -> ../../sdc
> lrwxrwxrwx 1 root root  9 Jul 31 13:17 usb-Generic-_MS_MS-
> Pro_20060413092100000-0:3 -> ../../sdf
> lrwxrwxrwx 1 root root  9 Jul 31 13:17 usb-Generic-
> _SD_MMC_20060413092100000-0:2 -> ../../sde
> lrwxrwxrwx 1 root root  9 Jul 31 13:17 usb-Generic-_SM_xD-
> Picture_20060413092100000-0:1 -> ../../sdd
> lrwxrwxrwx 1 root root  9 Jul 31 13:17 usb-Generic_Flash_HS-
> CF_26020128B005-0:0 -> ../../sdg
> lrwxrwxrwx 1 root root  9 Jul 31 13:17 usb-Generic_Flash_HS-
> COMBO_26020128B005-0:1 -> ../../sdh
> lrwxrwxrwx 1 root root  9 Jul 31 13:17 usb-INTENSO_USB_AA04012900007518-0:0
> -> ../../sdb
> lrwxrwxrwx 1 root root 10 Jul 31 13:17 usb-INTENSO_USB_AA04012900007518-0:0-
> part1 -> ../../sdb1
> lrwxrwxrwx 1 root root  9 Jul 31 15:20 wwn-0x5000c50065531ec5 -> ../../sdi
> lrwxrwxrwx 1 root root 10 Jul 31 15:20 wwn-0x5000c50065531ec5-part1 ->
> ../../sdi1
> lrwxrwxrwx 1 root root  9 Jul 31 13:17 wwn-0x5001480000000000 -> ../../sr0
> lrwxrwxrwx 1 root root  9 Jul 31 13:17 wwn-0x500a075112468483 -> ../../sda
> lrwxrwxrwx 1 root root 10 Jul 31 13:17 wwn-0x500a075112468483-part1 ->
> ../../sda1
> lrwxrwxrwx 1 root root 10 Jul 31 13:17 wwn-0x500a075112468483-part2 ->
> ../../sda2
> lrwxrwxrwx 1 root root 10 Jul 31 13:17 wwn-0x500a075112468483-part3 ->
> ../../sda3
> =============== %< ==============
> $ ls -l /dev/disk/by-label
> total 0
> lrwxrwxrwx 1 root root 10 Jul 31 13:17 boot -> ../../sda1
> lrwxrwxrwx 1 root root 10 Jul 31 13:17 gentoo -> ../../sda3
> lrwxrwxrwx 1 root root 10 Jul 31 15:20 intenso -> ../../sdi1
> lrwxrwxrwx 1 root root 10 Jul 31 13:17 swap -> ../../sda2
> =============== %< ==============
>
> However, when I boot a rescue system from a USB stick, the partition on the
> USB is not detected. I already tried latest SystemRescueCD (default and
> alternate kernel), Knoppix and the Gentoo Admin CD. Nothing, the partition
> is not available.
>
> What's the difference? Why does my kernel find this partition and the other
> one's do not? It's pretty silly to have a backup drive and cannot access it
> in question ;-)
>
> - Jörg
>
>

I can only think of two reasons, the kernel on the livecd doesn't
support GPT (which is unlikely) or you're booting a 32-bit kernel live
USB. I am reasonably certain for drives > 2TB a 64-bit kernel and GPT
are required.

Dan