[Solved] Installing on preformatted disk?

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turboscrew
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[Solved] Installing on preformatted disk?

Post by turboscrew » Wed Apr 17, 2019 5:32 pm

Is there a way to install Mint (in my case 19.1) on a preformatted disk?
It looks like the installer just reads the partition info and calculates a rough sizes of partitions, and then partitions the disk again by those rough sizes.
I even partitioned the disk with fdisk using block counts, but after installing, I saw that the block numbers had changed ALWAYS causing:
Partition 3 does not start on physical sector boundary.
(Start sector of partition 3 changed from 243273728 to 243275774 and there was originally 2048 block space between partition 2 and 3.)

My partition #3 is extended partition.

It lookss like if I opened the "change"-view, the partitioning changes. But without opening it, I don't know how to specify the mount points.
(Especially when I have multiple Linux-partitions.)
I know that the error message from "fdisk -l" is not serious, but it irritates me. It means that some older tools may not work right.

First I partitioned, then rebooted, then checked the partitions - all well this far, but after installing, the partitions had changed.
Last edited by turboscrew on Thu Apr 18, 2019 1:43 pm, edited 1 time in total.

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Larry78723
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Re: Installing on preformatted disk?

Post by Larry78723 » Wed Apr 17, 2019 5:49 pm

turboscrew, I'm no expert on installation but yes, Mint can be installed on a preformatted partition however it must be formatted as ext3 or 4. Another consideration is that I'm not sure Mint can be installed on an extended partition.

I'm sure one of the experts will be along shortly to give a more definitive answer.
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Mark Phelps
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Re: Installing on preformatted disk?

Post by Mark Phelps » Wed Apr 17, 2019 9:04 pm

An Extended Partition is not really a partition; instead, it is a container for one or more Logical partitions.

And yes, you can install on a Logical partition.

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turboscrew
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Re: Installing on preformatted disk?

Post by turboscrew » Wed Apr 17, 2019 11:31 pm

My formatting is: sda1 = root, sda2 = swap, sda3 = extended, sda5 = home, sda6 = backup stuff (not normally mounted).

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Re: Installing on preformatted disk?

Post by catweazel » Thu Apr 18, 2019 1:05 am

Larry78723 wrote:
Wed Apr 17, 2019 5:49 pm
Mint can be installed on a preformatted partition however it must be formatted as ext3 or 4.
This statement is false. Linux can be installed on any supported FS, including NTFS or FAT32.
Larry78723 wrote:Another consideration is that I'm not sure Mint can be installed on an extended partition.
Of course it can.
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Re: Installing on preformatted disk?

Post by catweazel » Thu Apr 18, 2019 1:06 am

turboscrew wrote:
Wed Apr 17, 2019 5:32 pm
Is there a way to install Mint (in my case 19.1) on a preformatted disk?
Yes. Just select the 'something else' option then tell the installer what partitions to use for /, and /home if you set one up.
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turboscrew
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Re: Installing on preformatted disk?

Post by turboscrew » Thu Apr 18, 2019 1:22 am

catweazel wrote:
Thu Apr 18, 2019 1:06 am
turboscrew wrote:
Wed Apr 17, 2019 5:32 pm
Is there a way to install Mint (in my case 19.1) on a preformatted disk?
Yes. Just select the 'something else' option then tell the installer what partitions to use for /, and /home if you set one up.
That's what I did. I wonder if the "catch" is the "format"-checkbox?
Maybe "no formatting" keeps the installer from repartitioning?

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Re: Installing on preformatted disk?

Post by hcentaur13 » Thu Apr 18, 2019 4:19 am

An extended partition is a container, holding logical drives. It is nothing that can hold operating system or plain data. In windows it is hidden by default. In linux it shows up as place holder for a number of logical drives.

The stucture of plain old DOS or compatibility mode partition table can hold only up to 4 partitions. Whereas one of the 4 partitions can be a extenden one. Whereas the extended partition is a partition holding a number of logical drives. A logical drive is section inside the extended partition that works like a partition. Each and all partitions are limited to 4 TB in size. So all logical drives together can not bigger than 4 TB in total.

All this limits are gone with the new type of partition table named GPT. This type is required by UEFI. Number and size of partitions are no longer limited other than through the size of the physical size of the physical device.

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turboscrew
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Re: Installing on preformatted disk?

Post by turboscrew » Thu Apr 18, 2019 1:27 pm

Finally!
For some reason, the installer wants a gap between the extended partition and a primary partition before that.
Fdisk doesn't suggest that.
And the installer adds 2047-sector gap that pisses fdisk off. If there's a gap fdisk thinks the next partition should start at 1MiB boundary.

This seemed to work:

Code: Select all


root = 2048 to 209715199 (+209713151)
swap = 209715200 to 243269631 (+33554431)
gap
ext = 243271680 to end
gap
home = 243273728 to 872419327 (+629145599)
gap
backup = 872421376 to end
Now both Mint installer and fdisk seem to be happy.
(the "gap" is the 1MiB = 2048 sectors alignment)

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turboscrew
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Re: [Solved] Installing on preformatted disk?

Post by turboscrew » Fri Apr 19, 2019 9:38 am

I think there's a small bug in the installer. I installed Debian on another machine with exactly similar disk. Debian didn't need the gap between the extended partition and the primary partition before that.

Maybe it confuses offset to last block of partition and partition size (offset to the beginning of the next partition)?

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