Partition sizes for Amiga OS 3.1 (SCSI)?

[Thomas]

"End capacity" might be lower. But your example does not mention end capacity. Your example shows low level format, number of sectors.

File system overhead is another story. For example an empty Amiga floppy formatted with OFS has 837 KB free, not 880K.

For harddrives the low level format is given by the manufacturer and cannot be changed by the operating system. If a harddrive is labelled as 4GB, it has ca. 8,000,000 sectors. This number is fixed for all operating systems.

File system overhead seldomly reduces the formatted capacity by more than 0.1 percent. OFS is a bad example. With FFS for example you get 879KB out of the formatted 880KB. File systems of other operating systems are similar.

[danbeaver]

So the type of file system, error correction, sector size, allocation size, file allocation table, all take essentially nothing away from raw storage capacity of the drive?  Odd, I've never heard this before; tell me more.

[Amiwest]

Some good reading on the 4gb limits.
http://thomas-rapp.homepage.t-online.de/4gb_faq.html
http://thomas-rapp.homepage.t-online.de/filesyslimits.html
http://www.youngmonkey.ca/nose/articles/NewTekniques_9810/AmigaInMotion.html

[Thomas]

So the type of file system, error correction, sector size, allocation size, file allocation table, all take essentially nothing away from raw storage capacity of the drive?

That's not what I said. They take their needed space when it is needed. But an empty partition is empty. Almost. 0.1 percent of for example 2 GB is 2 MB. Should be enough to store nothing but the volume name and the information that there is nothing.

BTW, you are mixing all up. Error correction is part of the low-level format. It does not account into the 512 bytes user data. Sector size is fixed, I said this already.

If you like pre-allocated storage so much, you can use PFS3. It allocates 20% of the partition from the beginning. On the other hand, it uses the remaining space for data only. All meta-data is stored in the 20%.

This means that on other file systems more space than the file size divided by sectorsize is needed for each file while with PFS3 a file occupies exactly this space only.

[danbeaver]

I'm not interested in pre-allocated storage, but how a file system and all of its overhead takes virtually no space.

[utri007]

I'm not interested in pre-allocated storage, but how a file system and all of its overhead takes virtually no space.

With GVP there shouldn't be 4gb HD limit, only limit should be  fast file systems's 2gb partition limit

[danbeaver]

With GVP there shouldn't be 4gb HD limit, only limit should be  fast file systems's 2gb partition limit

So a raw hard drive from the factory when subsequently formatted in FAT, FAT32, NTFS, ,FFS, SFS, etc. on a GVP has virtually the full capacity of the new unformatted hard drive after any file system is then applied?

[Thomas]

I'm not interested in pre-allocated storage, but how a file system and all of its overhead takes virtually no space.

Like I said, it takes its space when it's needed. For example to store a file of 500 bytes it needs two sectors, not one as you might expect.

[blakespot]

Ok, back in town. HDToolBox riding gvpscsi.device reports the following about this "4GB" drive after Read Configuration:

File Name: drive definitions
Manufacturer's Name: SGI
Drive Name: Seagate ST34572W
Drive Revision: 0878

Cylinders: 918
Heads: 1
Blocks Per Track: 9674
Blocks Per Cylinder: 9674

Size: 241225K (235MB)

Park Head Where? (Cylinder): 918

Information on this drive:
http://pbclub.pwcsite.com/PBInfo/PB%20Info%20Site/pb/harddrive1/34572wovw.asp.htm

Thanks for any help on this.


bp

[Thomas]

918 * 1 * 9674 * 512 = 4,546,934,784 Bytes

= 4.547 GB = 4.235 GiB = 4.0 GiB + 235 MiB

So everything is right so far.

In order to stay below 4 GiB, just reduce the number of cylinders by 51.

867 * 1 * 9674 * 512 = 4,294,327,296 Bytes = 3.999 GiB.

(2 ^ 32 = 4,294,967,296; that's the magic limit)


Edit: given that the drive is bigger than 4GB and is not yet installed (which means that changing values does not destroy existing data), you could use these completely different values:

Cylinders = 4096
Heads = 1
Blocks per Track = 2048
Blocks per Cyl = 2048

Then you'll get exactly 4 GiB.

[blakespot]

Thank you!

Now that that's sorted, 2GB is the max partition size for AmigaOS 3.1, yes?

I am using HDToolBox. I also have GVP's FaaaaaaastPrep app, can I ignore that in setting this up?

Thanks.



bp

[Thomas]

Now that that's sorted, 2GB is the max partition size for AmigaOS 3.1, yes?

AFAIK FFS does not have a partition size limit. But some old programs (including the Commodore Installer) refuse to copy data to a partition which has more than 2 GB of free space. Therefore it is a good idea to limit the partition to 2 GB, then there never can be more than 2 GB free.

I am using HDToolBox. I also have GVP's FaaaaaaastPrep app, can I ignore that in setting this up?

I don't know what Fa...astPrep does. As long as the controller is RDB-compatible, HDToolbox should be fine.

[scuzzb494]

Just as an aside, just be mindful of the different connections between a W ref and a WC

Connections
1 x Storage - Ultra Wide SCSI - 80 pin Centronics (SCA-2)  WC
1 x Storage - Ultra Wide SCSI - 68 pin HD D-Sub (HD-68) W

Just that the WC may not be suitable for your Amiga. I say may not. I am no expert, just that I had problems buying drives and then finding I couldn't fit them. And I really only ever bothered with 2.1s cus I had real probs with the bigger drives. Even after I thought I had got them working, they suddenly became corrupt. And that was with a GVP on a 2000.