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Assume that we have two disks, one master SATA and one master ATA. How will they show up in /dev?

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up vote 14 down vote accepted

Depending on your SATA driver and your distribution's configuration, they might show up as /dev/hda and /dev/hdb, or /dev/hda and /dev/sda, or /dev/sda and /dev/sdb. Distributions and drivers are moving towards having everything hard disk called sd?, but PATA drivers traditionally used hd? and a few SATA drivers also did.

The device names are determined by the udev configuration. For example, on Ubuntu 10.04, the following lines from /lib/udev/rules.d/60-persistent-storage.rules make all ATA hard disks appear as /dev/sd* and all ATA CD drives appear as /dev/sr*:

# ATA devices with their own "ata" kernel subsystem
KERNEL=="sd*[!0-9]|sr*", ENV{ID_SERIAL}!="?*", SUBSYSTEMS=="ata", IMPORT{program}="ata_id --export $tempnode"
# ATA devices using the "scsi" subsystem
KERNEL=="sd*[!0-9]|sr*", ENV{ID_SERIAL}!="?*", SUBSYSTEMS=="scsi", ATTRS{vendor}=="ATA", IMPORT{program}="ata_id --export $tempnode"
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If I'm understanding your question correctly, the first parallel ATA hard drive under Linux will be /dev/hda, the second will be /dev/hdb, followed by /dev/hdc, etc.

Serial ATA devides will show up the same way SCSI and USB devices do: /dev/sda will be the first one, followed by /dev/sdb, /dev/sdc/, etc.

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I don't think this is true any more. At least with recent Fedora release, parallel ATA disks get /dev/sda etc too. – fschmitt Sep 26 '10 at 18:00
This is how it is on my Ubuntu machine, but I'm not bleeding edge, so maybe it's different. – Josh Sep 26 '10 at 18:04

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