Partition sizes for Amiga OS 3.1 (SCSI)?

[blakespot]

Software or a hardware question? Hmm.

I have a 700MB SCSI HD on my GVP HD+8 SCSI controller in my A2000 w/ OS 3.1. I need to add a bigger disk. What is the max partition size under OS 3.1, ROM 3.1? Will a 40GB, 80GB, etc. disk work (even if nowhere near that space needed)?

Things to look out for? The Quantum drive I have is circa 1994. More modern drives present issues?

Thanks.



bp

[Thomas]

Partition size limit is a software question.

But you are not asking for partition size limit but for harddrive size limit. Harddrive size limit is 4GB. You can connect a bigger drive if you use only the first 4GB of it. You can use more than 4GB with the right software.

Partitions must not be created outside the harddrive size limit. If you create a partition outside the first 4GB area (or crossing the boundary), writing to this partition will corrupt other partitions sooner or later. It's dangerous to deal with large harddrives.

[magnetic]

Yes like thomas said it doesnt matter the interface (scsi) its os restriction

[blakespot]

So I have this 7,200 RPM Seagate 4GB SCSI drive laying around.

SCSQuery tells me it has 6300 cylinders. It has 8 heads. How do I calc for HDToolBox Blocks / Track, Blocks / Cylinder to get a full 4GB? Interleave is 1.

I enter 6300 cylinders, but it changes nothing - I hear that #, tho it is in an editable field, is calculated by the other two values I mentioned.

Thanks.

Drive is a Seagate Barracuda ST34572WC.


bp

[Thomas]

Click on Read Configuration, then the values should be right.

Size is calculated as Cylinders * Heads * Blocks per Track * 512
Blocks per Cyl is calculated as Heads * Blocks per Track.

There are only very rare cases where you have to edit the values.

[blakespot]

I had it Read Configuration and while the vendor info is accurate, the physical attrib returned call it a 23MB drive. It is a 4GB drive. (Returns 1 head instead of 8, etc.)


bp

[Thomas]

Please post all values as read by Read Configuration.

If the drive is 4119 MB, it will be shown as 23 MB because everything above 4GB (= 4096 MB) is cut off.

[blakespot]

Please post all values as read by Read Configuration.

If the drive is 4119 MB, it will be shown as 23 MB because everything above 4GB (= 4096 MB) is cut off.

I will do so once I get back into town - out on vacation until Thurs evening. Thanks.


bp

[blakespot]

Something I noticed. Here is a picture from the 'net of the same drive (same model #):

http://www.4drives.biz/images/DRIVEPICTURES/IBM_02K3404.jpg

It says 4.51GB USCSI. My drive says 4GB SCSI in the same place. I see more references to this model being 4.5GB than 4GB. I wonder why my drive is labelled as such? Two drives with same model # differing by .5GB seems odd.

My drive came in an SGI O2 and HDToolBox's Read Configuration reports both Seagate and SGI in the text details.

It seems I may have a 4.5xGB drive. Steps, then?

Thanks.



bp

[danbeaver]

There is a raw, unformatted size for a drive and after a format lays down the file system there is a much lower size; this is why the Amiga got 880K from a floppy DD, Apple got 800K, and IBM got 720K.

[zipper]

I think I had a similar one once; prepped it with P5 tools and was asked if the size should be restricted to 4 GB which I did.

[Thomas]

There is a raw, unformatted size for a drive and after a format lays down the file system there is a much lower size; this is why the Amiga got 880K from a floppy DD, Apple got 800K, and IBM got 720K.

This does not apply to harddrives. They are formatted by the manufacturer and have a fixed number of sectors. All of these sectors are available to the operating system.

[Thomas]

Something I noticed. Here is a picture from the 'net of the same drive (same model #):

http://www.4drives.biz/images/DRIVEPICTURES/IBM_02K3404.jpg

It says 4.51GB USCSI. My drive says 4GB SCSI in the same place. I see more references to this model being 4.5GB than 4GB. I wonder why my drive is labelled as such? Two drives with same model # differing by .5GB seems odd.

My drive came in an SGI O2 and HDToolBox's Read Configuration reports both Seagate and SGI in the text details.

It seems I may have a 4.5xGB drive. Steps, then?

Thanks.



bp

Please post all values as read by Read Configuration. Then I can tell you which values to use to restrict the drive to 4GB. IMHO there is no point to take the hassle with scsi driver patches and third-party file systems just for 0.5 GB.

[danbeaver]

This does not apply to harddrives. They are formatted by the manufacturer and have a fixed number of sectors. All of these sectors are available to the operating system.

So the low level format size of a hard drive determines the end capacity regardless of the type of file system, cluster size, ECC overhead, etc.?

[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.