How to get the total size of an unmounted partition in Linux?

For example "/dev/sdb1"

Rainer Stratmann wrote

How to get the total size of an unmounted partition in Linux?

Can you use the info at
http://serverfault.com/questions/190685/whats-the-best-way-to-get-info-about-currently-unmounted-drives ?

Just googled you question ;-)

You can run these commands and parse the output.

Bart

Thanks, it is may interesting.
Better would be a syscall.

Am 19.12.2014 13:54 schrieb "Rainer Stratmann" <

http://serverfault.com/questions/190685/whats-the-best-way-to-get-info-abou

You'll likely need to check for IOCTL values you can then pass to an opened partition node per FpIoctl. I don't know them though, so I can't help you there...

Regards,
Sven

I think this is a question that doesn't have a straightforward answer. For example, you refer to an "unmounted partition", but partitions aren't mounted: filesystems are mounted, and without knowing the type of filesystem you don't know how much overhead is associated.

The canonical program that looks at partition sizes is fdisk, and painful experience has taught me that different fdisk implementations can return different results. Sometimes the differences are subtle, sometimes not.

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On Fri, 19 Dec 2014 13:53:23 +0100, Rainer Stratmann () wrote about "Re: [fpc-pascal] Size of a
partition" (in ):

t-currently-unmounted-drives ?

> > Just googled you question ;-) Thanks, it is may interesting.

Probably not, actually. ... :-)

Better would be a syscall.

This stuff is all in sysfs. Attached is some code that can get you started on a more sensible path.

HTH.
- --
Regards,

Dave [RLU #314465]
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I have been trying to use tStringList in a larger project of mine, but this just keeps bombing out with a exception.
I have been able to reproduce the problem with this very simple test program:

program project1;
USES Classes;
Var T : tStringList;
     S : String;
begin
   S := 'Test';
   T.Create;
// T.Clear;
   T.Add (S);
   T.Free;
end.

It will throw the exception at each and every instruction using T after the T.Create statement.

The project is a simple command line program, tested both with Lazarus 1.2.6 and the included default install of FPC 2.6.4 on either Windows 8.1/64 or Windows 10/32...

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You're mixing old TP-style objects with classes.

T := TStringList.Create is the correct syntax.

Regards,

Joost.

On Fri, Dec 19, 2014, 12:49 Ralf Quint wrote:

I have been trying to use tStringList in a larger project of mine, but this just keeps bombing out with a exception.
I have been able to reproduce the problem with this very simple test program:

program project1;
USES Classes;
Var T : tStringList;
     S : String;
begin
   S := 'Test';
   T.Create;
// T.Clear;
   T.Add (S);
   T.Free;
end.

It will throw the exception at each and every instruction using T after the T.Create statement.

The project is a simple command line program, tested both with Lazarus 1.2.6 and the included default install of FPC 2.6.4 on either Windows 8.1/64 or Windows 10/32...

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Well, then why is the compiler building this just fine without even throwing an error?!?!?
As mentioned, I do not get the call, but at
anything after that...
I do not have a working Delphi system at hand right now, but I am sure that this would have compiled and worked on anything up to Delphi 2006 just fine.

I will change this and see if this makes a difference, thanks

Ralf

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Hi Dave!

that's exactly what I was searching for.
Thanks a lot.

One question is left:

Where can I read the blocksize. Normally it is 512 bytes. But there are (newer) devices where there is a different blocksize. Also a CD has a different blocksize as far I know.

/sys/block/sda/queue/hw_sector_size

logical_block_size
physical_block_size

and so on

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On Sat, 20 Dec 2014 00:00:35 +0100, Rainer Stratmann () wrote about "Re: [fpc-pascal] Size of a
partition" (in ):

Hi Dave! that's exactly what I was searching for. Thanks a lot.

You're welcome.

There are 2 functions in the unit to do that:
get_physical_sector_size() and get_logical_sector_size().

If the disk's sector size is 512 bytes they will give the same answer. Likewise, for a CD or DVD they will give the same answer of 2048 bytes.

If a disk has a physical sector size of 4096 bytes, it is up to the SATA/SAS driver to publish a logical sector size of either 4096 or
512. I think this configuration is determined when you partition the drive, where using GPT sets it to 4096 and using DOS-style partition reverts it to 512 bytes, but this is just my guess -- I don't have a large disk on which to test.
- --
Regards,

Dave [RLU #314465]
*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-* (David W Noon)
*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*

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throwing an error?!?!?

Because Create is a legal method call as well. You can call a constructor like a normal method on an existing instance.

As mentioned, I do not get the call, but at anything

after that...

I do not have a working Delphi system at hand right now, but I am sure

that this would have compiled and worked on anything up to Delphi 2006 just fine.

Delphi will compile this (like FPC does), but it will me here, I did the mistake a few times myself when I thought about too many other things.

Regards,
Sven

Am 20.12.2014 00:01 schrieb "Rainer Stratmann" <

different

blocksize as far I know.

Please note that there are drives that internally have 4kB, but emulate 512B ones. On SATA ports you can determine this, but if you connect them using some USB adapter you might not be able to detect this. Depending on what you plan to do thus is important (e.g. copying large amount of data would be better done in 4kB blocks or multiples of that).

Regards,
Sven

Delphi will compile this (like FPC does), but it will me here, I did the mistake a few times myself when I thought about

too many other things.

Regards, Sven

Yes and this is just sad.
Is there a reasonable case for not disallowing call of constructor as method outside constructors (of the class itself)?

Best regards,
Flávio