Author Topic: Size limits  (Read 519 times)

John Poltorak

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Size limits
« on: June 29, 2017, 11:13:57 pm »
Can someone point me to a  reference for size limits for various filesystems such as FAT, FAT32,  exFAT,  HPFS,  JFS, NTFS, for file size, partition size, disk size?

Also what are the limits which LVM can handle?

If I have a 2TB disk, can I use it under OS/2 and if so how?



Pete

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Re: Size limits
« Reply #1 on: June 29, 2017, 11:59:44 pm »
Hi John

LVM screws up at 512Gb but it is possible to use a 2Tb drive prepared using dfsee - once "dfsee'd" the drive is shown as the correct size in LVM.

The drive can be formatted JFS - max size for filesystem - or you can split the drive into multiple volumes.


Regards

Pete
 

« Last Edit: June 30, 2017, 12:05:17 am by Pete »

André Heldoorn

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Re: Size limits
« Reply #2 on: June 30, 2017, 03:56:18 am »
Can someone point me to a  reference for size limits for various filesystems such as FAT, FAT32,  exFAT,  HPFS,  JFS, NTFS, for file size, partition size, disk size?

Wikipedia, comparison of file systems?

John Poltorak

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Re: Size limits
« Reply #3 on: June 30, 2017, 09:50:08 am »
Many thanks...

https://en.wikipedia.org/wiki/Comparison_of_file_systems

I'm amazed that there are so many file systems.... They managed to overlook  HPFS386 though...

André Heldoorn

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Re: Size limits
« Reply #4 on: June 30, 2017, 10:36:50 am »
They managed to overlook HPFS386 though...

Yes, but only if we'd ignore the essentials of their HPFS386 page.

John Poltorak

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Re: Size limits
« Reply #5 on: July 01, 2017, 11:57:56 am »
Hi John

LVM screws up at 512Gb but it is possible to use a 2Tb drive prepared using dfsee - once "dfsee'd" the drive is shown as the correct size in LVM.

The drive can be formatted JFS - max size for filesystem - or you can split the drive into multiple volumes.


Regards

Pete

Thanks Pete.

Are you saying that once DFSEE has done whatever it needs to do, then LVM is able to function properly? If this is a bug in LVM, has it been identified as something which needs fixing? BTW  are there different versions of LVM and if so how to identify them? BLDLEVEL did not return any version information on LVM.EXE from CP2.

Actually, when you mention this problem with LVM, I wonder if it is responsible for identifying one of my boot partitions on the Boot Manager Menu as being -16528M whereas it is 49007M. Boot Manager also shows it as HPFS, whereas it is really JFS.

Pete

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Re: Size limits
« Reply #6 on: July 01, 2017, 02:24:00 pm »
Hi John

Yes, once a disk >521Gb has been prepared by dfsee (if memory is correct this involves Wipe start of disk to zero) it can be used by LVM. Yes, this is the reason LVM reports the size of partitions incorrectly on disks >512Gb.

I think it is a case of LVM is now very old - I think the latest is from around 01/2006, date is probably the only way to identify builds  - and was not built to cope with a disk larger than 512Gb.

it would be nice to get LVM updated but I doubt IBM will give you the source code. Both eCS (2.0 on) and ArcaOS get around the problem by including a disk preparation tool - a cutdown dfsee I believe - to prepare disks between 512GB to 2Tb.


Regards

Pete



John Poltorak

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Re: Size limits
« Reply #7 on: July 16, 2017, 04:53:24 pm »
Hi John

LVM screws up at 512Gb but it is possible to use a 2Tb drive prepared using dfsee - once "dfsee'd" the drive is shown as the correct size in LVM.

The drive can be formatted JFS - max size for filesystem - or you can split the drive into multiple volumes.


Regards

Pete

Hi Pete,

I have a 500GB drive (LVM  sees it as 476937MB) so I'm not exactly sure if it has reached this LVM 'screw up' limit but I'm unable to create partitions on it using LVM. Guess I'll have to bite the bullet and try doing something with DFSEE...

Doug Bissett

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Re: Size limits
« Reply #8 on: July 16, 2017, 06:44:42 pm »
Quote
I have a 500GB drive (LVM  sees it as 476937MB) so I'm not exactly sure if it has reached this LVM 'screw up' limit but I'm unable to create partitions on it using LVM. Guess I'll have to bite the bullet and try doing something with DFSEE...

There are many possible reasons for this. One is that even on 500 GB disks, the disk geometry is made the same as for 2 TB disks. Windows uses a geometry that LVM doesn't understand. It is not a LVM screwup, it is simply that LVM can't use what is there, so you need to change it (LVM won't allow you to change something that it doesn't understand). To change it, you need to backup the whole disk, using a backup method that will not restore the geometry (in the MBR) when you restore it. Before restore, you need to wipe the disk (use DFSEE to wipe the front of the disk, it is a menu item). Then recreate all of the partitions, as you want them, using an OS/2 tool (I recommend LVM, but DFSEE will also do it, as long as DFSEE is running under OS/2). Add LVM drive letters, as required, and install the Air Boot boot manager. Restore the windows partition(s), then install the desired OS/2 to the prepared partitions (properly called "volumes").

FWIW, the ONLY windows backup tool, that I know of, that will do it properly, is Acronis (if you have a Seagate drive, you can get the cut down version, called Seagate Disk Wizard - you just need a Seagate drive attached to be able to use it - USB will do). Do NOT restore the MBR, or you will end up back where you started. Use the backup option for partitions, not the whole disk, and include all of the partitions.