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Let’s say I have 50 USB flash drives.

I assume they get to be /dev/sda to /dev/sdz. What comes after /dev/sdz?

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  • Extension of the same question - what happens with virtual xvd devices like /dev/xvda ? NVME devices of the format /dev/nvme1n1 or with partiiton nvme2n1p3 Does the old format IDE driver giving /dev/hda device nodes have the same limits ? Commented Apr 1, 2022 at 23:05
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    Amusingly, I once tried to help a Windows user who had run out of drive letters. This was years ago. He had two floppies, several compressed drives (each uses two drive letters), external drives and several CD-ROMs and DVDs. Drive A: to drive Z: is all you get. Commented Apr 2, 2022 at 14:17
  • @Wastrel At that point you start mounting additional volumes under directories. Yes, that is a very *nix-like approach. Works fine. The underlying physical device paths are numerical, so it'll happily keep incrementing forever (\Device\HardDisk1, etc.). Commented Apr 3, 2022 at 15:17

1 Answer 1

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It will go to /dev/sdaa, /dev/sdab, /dev/sdac, etc.

Here is a comment from the source code:

/** * sd_format_disk_name - format disk name * @prefix: name prefix - ie. "sd" for SCSI disks * @index: index of the disk to format name for * @buf: output buffer * @buflen: length of the output buffer * * SCSI disk names starts at sda. The 26th device is sdz and the * 27th is sdaa. The last one for two lettered suffix is sdzz * which is followed by sdaaa. * * This is basically 26 base counting with one extra 'nil' entry * at the beginning from the second digit on and can be * determined using similar method as 26 base conversion with the * index shifted -1 after each digit is computed. * * CONTEXT: * Don't care. * * RETURNS: * 0 on success, -errno on failure. */ 

Source

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