David Tansey wrote:
>
> maybe this was answered somewhere, but i could not find it.
>
> you said "partitions." That doesn't mean i can boot my windows partition (which
> is something under 2GB) does it? (I had thought plex couldn't do that)
If the mods work, then you could do this. However, we don't have any
write-cache code written yet. The cache would protect your partition
by opening it read-only and storing writes in a cache. So if you
did boot a win partition currently, your partition could get
screwed up.
> also, does this mean i can make 2GB disk files for HD images??
This should also be possible if the mods work.
> lastly, supposedly linux 2.4 will allow for filesized in the TB... does that
> mean plex will support even bigger HD images or is that plex dependant not
> kernel dependant?
Here's a little summary of limits. The effective limits due to
the BIOS limits combined with the IDE limits are on the right column.
(from the Phoenix Enhanced disk drive spec May 9, 1995)
BIOS IDE Limit
sectors/track 63 255 63
heads 256 16 16
cylinders 1024 65536 1024
capacity 8.4G 136.9G 528M
So, via the BIOS with the LBA mods, it is possible to generate
offsets of up to 8.4G, which are passed on to the host OS
to handle. Using a real IDE driver, this limit would be 136.9G.
Now we run into another layering of limits - the host OS
interface. I believe the newer glibc versions have the capabilities
to handle file IO with files > 2GB. You couldn't do this
before, because the 'off_t' parameter to lseek() was a 32-bit
int (-2G..+2G). Now there's a llseek().
But, file IO goes through (in Unix) the Virtual File System layer (VFS) to
the specific file system code for the partition type you are using.
A lot of Linux users for instance, use ext2. Ext2 can handle large
_partition_ sizes, but only 2GB _file_ sizes when formatted with
512-byte sectors.
So the answer would be:
- If using the BIOS, you will hit the wall at 8.4G
or the file size limitation of your filesystem, whichever is smaller.
- If using an OS IDE driver, you hit the wall at 136.9G
or the file size limitation of your filesystem, whichever is smaller.
If using a special guest OS specific driver, it would be possible
to emulate an arbitrarily defined hard disk device controller
(non-IDE) and thus the limit would then soley be your host OS
filesystem's limit.
--
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Kevin Lawton [EMAIL PROTECTED]
MandrakeSoft, Inc. Plex86 developer
http://www.linux-mandrake.com/ http://www.plex86.org/
