FAT32 Partition Limit?

[Prospero]

I haven't been able to find this anywhere, but what is the max size partition FAT32 will recognize? Something in the back of my mind remembers reading 78gigs somewhere, but I have no clue. Help me please?

Prospero

[Dr Mordrid]

The max partition for FAT32 is 2 terabytes (2000 gigs). This, however, doesn't stop your mainboards BIOS from supporting less. The actual max partition size for a given mainboard will depend on the state of the int13h extensions, if any, in the boards BIOS. These extensions allow for mapping more sectors than allowed for in the original int13 spec.

The best way to find out the numbers for your particular board/BIOS combination is to contact the manufacturer or to visit their newsgroup and ask. The limit for many current mainboards maxes out at about 136 gigs or so, with most older boards only accepting 8 - 32 gigs absent a BIOS update.

It's my understanding that the Promise RAID cards impose their own limits which can, and often do, exceed those of the system BIOS. I'm not sure if this extends to their ATA adapters, but it seems logical that it does since their BIOS's are similar. I'll contact my Promise contact to get a real answer to this.

A tertiary issue is how large a partition FDISK can "see". This is, however, a cosmetic issue as current versions of FDISK will create very large partitions. It's just that FDISK cannot report their size accurately if they are over 64 gigs.

Dr. Mordrid



[This message has been edited by Dr Mordrid (edited 05 December 2000).]

[Prospero]

Thanks Doc. Would I gain anything by using a program like partition magic to do the partitioning? I'm using the onboard adapter on a KT7RAID at the moment. I currently am using two IBM 75GXP 30 gigs for a 60gig RAID 0, but am looking for something bigger. HUFFYUV does eat the space.

[Dr Mordrid]

I use Partition Magic 5 all the time and yes it's worthwhile. Besides partition manipulation (partition resize, copy, format changing etc.) it also comes with BootMagic for setting up multiboot systems. Great product.

Now for the meat of the Promise comment in my previous post; YES, the Fasttrak and ATA cards have their own large drive support.

How large this is depends on how you count gigabytes: 1000k or 1024k. The max size would be 137 or 128 gigs respectively. For purposes of further discussion I'll use the 128 gig number. In this example a Promise Ultra ATA66/100 card could have up to a 128g drive attached regardless of the system BIOS's limitation. Only the OS/filesystem is now a problem.

Win95a would not work with this very well given its 2 gig FAT16 partition limit. Win98/FAT32 would not offer much of a problem given its 2 terabyte partition limit.

Now for the good stuff: on the current Fasttrak's this 128g size limitation is PER DRIVE, not per array.

This means that you could theoretically have four 128 gig drives hooked up into a 512 gig array with the current setup. Promise has tested this up to 300 gigs (4x75g), but will not offer official support for it. They tested it under Win98/ME/NT/Win2000.

As larger drives are introduced they plan on supporting further int13h extensions to support them. That means that down the road a multi-terabyte array could thoretically be built.

Example: presume that some new int13h translation scheme comes out with a 2 terabyte limit, thereby allowing the production and use of drives up to this size. With 4 such drives on the FastTrak you could set up an 8 terabyte array given a BIOS update permitting it.

Of course, this is all subject any drive and/or partition size limits the OS may impose. This would, of course, limit the use an 8 terabyte array to NTFS or some subsequent filesystem that could handle such a monstrosity. FAT32 would start smoking at 2 terabytes.

NOW for the practical side:

Such an array, while large, would be so fast that it would easily overrun the PCI/33 32 bit bus's 133mb/s bandwidth. So, we end up with a huge array but are incapable of using it's full speed potential. What to do.....

Answer: wait until Feb/March 2000 for the next new Fasttrak100 4 channel to come out. This Fasttrak will run on the new PCI/66 64 bit slots which can deliver a 256 mb/s bandwidth. It also treats each drive as a separate entity; no master/slave drives as with the current models.

Boards with PCI/66 64 bit slots are starting to appear now, most notably the new Asus CUR-DLS server board. This beast has 2 PCI/66 slots and 5 PCI/33 slots, 2 x SCSI-2, NIC, PC133 memory etc. etc.

Drooling yet?

Dr. Mordrid


[This message has been edited by Dr Mordrid (edited 06 December 2000).]

[Prospero]

Cleaning the slobber off my keyboard now.