[Bug 704412] Re: /dev/sda is not limited to 20 partitions
psusi at ubuntu.com
Fri May 13 01:16:06 UTC 2016
** Branch linked: lp:~psusi/ubuntu/yakkety/installation-guide/partition-
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/dev/sda is not limited to 20 partitions
Status in installation-guide package in Ubuntu:
Linux limits the partitions per drive to 15 partitions for SCSI
disks (3 usable primary partitions, 12 logical partitions), and 63
partitions on an IDE drive (3 usable primary partitions, 60 logical
partitions). However the normal Ubuntu system provides only 20
devices for partitions, so you may not install on partitions higher
than 20 unless you first manually create devices for those
This is misleading since the transition from /dev/hda to /dev/sda as the
latter now enforces a limit of 16 minor devices per drive.
$ ls -l /dev/sd[ab]
brw-rw---- 1 root disk 8, 0 2010-12-30 16:28 /dev/sda
brw-rw---- 1 root disk 8, 16 2011-01-13 16:32 /dev/sdb
0 is the whole drive, 1-4 are the primary partitions, 5-15 are the
logical partitions. So there's now a limit of 15 partitions per drive,
assuming you've used all of the primary partitions.
A friend of a friend found installation failed on creating the three
partitions for /, swap, and /home. The first two succeeded, the third
failed with an error passed on imprecisely as "the 17th partition"
couldn't be created. The guide suggests 20 should be OK.
"oh, wait, I'm evidently misremembering and the /dev/sd* limit is indeed
16. Yes, I suppose that should be documented in the installation
guide." -- Colin Watson, #ubuntu-installer, 2011-01-17 10:21.
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