Best partition scheme for a large USB device.

Best partition scheme for a large USB device.

Post by Noate » Mon, 23 Apr 2007 00:39:21

Hello all,

Is there a best practice or way to partition a large (500GB) USB
storage device?
Should I split the thing in 1/2, 1/4s?
Is it ok to create a raw ext3 filesystem on the whole drive without
creating a partition?
Are there any absolute no-nos?

Thanks in advance.

Best partition scheme for a large USB device.

Post by » Mon, 23 Apr 2007 01:56:13

If this harddrive is a new one, you can create the filesystem without
checking for bad blocks (mkfs.ext3 ... /dev/sda without the option "-
c") This saves time.
And I prefer partitioning, beacause of the blocksize in the filesystem.


Best partition scheme for a large USB device.

Post by Douglas Ma » Mon, 23 Apr 2007 10:47:10

I'd argue for the opposite for new drives, especially USB drives; that
is, I'd run badblocks (with write testing) to confirm the drive has a
chance of working as intended. This is important because S.M.A.R.T. does
not work with USB, IME.

To the OP: There are no hard and fast rules when using a modern GNU/Linux
distribution to access the drive. You could use it all in one partition,
if you want, but I've included some factors for consideration below. When
partitioning and using large external USB disks, consider the following:

a) Consider reserving 8G for use as a bootable partition. The drives are
so big, you won't miss it and adds to recovery options.

b) Consider using encryption for backups, etc. Device mapper encryption
allows all partitions to be encrypted. It can give some peace of mind
should the drive ever be lost or stolen.

c) Consider using a journalling filesystem, (on top of encryption as
applicable.) I like xfs.

d) Consider adding redundancy. what would happen if the drive failed and
took 500G of data with it? I have recommended using these drives in pairs
for data redundancy.

Douglas Mayne

Best partition scheme for a large USB device.

Post by Matt Giwe » Mon, 23 Apr 2007 13:11:16

I can't speak for 500M sizes but these are the results I got putting ext3 on
three usb externals. (I discovered bittorrent.)

120G == 113 free = 7
250G == 230 free = 20
320G == 294 free = 26

Looks reasonable to me. If I had a 500 (two 320s are the same or cheaper at the
moment) I would first try formatting without partitioning and see what happens.
Obviously I crossed some kind of threshold between 120 and 250 but 250 to 320 is

The only second thought I have had is that if the external is only for storage
then ext2 should be fine and none of that lost journal space. Only drives with
frequent reads and writes would I use ext3. Without regular accesses there
should be no reason for fsck-ing save in the rare case of a crash during an
access. I was very happy with ext3 at the 40GB disk size as the fsck took on the
order of 20 minutes with ext2. That is just something I have thought of doing if
I get another but I probably won't try to do "better" as I have "good enough."

Rather I am getting around to looking up taking better control of the journal
file size as storage cannot possibly need one as big as a potentially multi-user
system with many operations going at one time. I will be looking to get the
journal to the bare minimum which is presumably no larger than twice the largest
file that may be accessed at the time of a power outage or some such. But that
would be something like 4.6GBx2 which isn't that much different from the
default. So it is not very high on my study priority.

Also my experience says that if you do something other than the simplest
defaults take good notes on paper and put that where you will not lose it. Being
too clever by half is a pain sometimes.

If Americans knew about Israel's treatment of non-Jews they would turn
against Israel as fast as they did against apartheid South Africa.
-- The Iron Webmaster, 3737
Larry Shiff

Best partition scheme for a large USB device.

Post by Noate » Wed, 25 Apr 2007 06:07:07

On Apr 21, 11:11 pm, Matt Giwer < XXXX@XXXXX.COM >

This is all great info, thanks for all the insight.
I, ( meaning the company I work for ) bought 4 x 500 GB Fantom drives
( Century Corp.) to use for acquisition data.
The one we had for our team is a Lacie. This is the one that had major
I've since retired it to NTFS only, but I had created an ext3
filesystem using the whole drive.
I don't recall ever running fdisk to create a partition. Just
wondering whether it was me or the drive.

Thanks again.