DA Morgan wrote:
> Frank wrote:
>
>
>>DA Morgan wrote:
>>
>>>Billy Verreynne wrote:
>>>
>>>
>>>
>>>>Frank wrote:
>>>>
>>>>
>>>>
>>>>>Could some OS guru elaborate on why some OS's only handle 2GB?
>>>>>Seems to me these must be 31 bit then. (AIX 4.x had a special
>>>>>'add-on' to go beyond 2GB, looked like the MSB was enabled, so to speak)
>>>>
>>>>Won't call myself an OS guru, but I will have a bash (don't like ksh or csh
>>>>that much ;-).
>>>>
>>>>Firstly, it has _nothing_ to do with operating system and _everything_ to do
>>>>with the file system.
>>>>
>>>>And this type of problem has been around for a long while. Back in my
>>>>mainframe days, the filesystem used on the Siemens BS2000 o/s (still IMO
>>>>one of the best mainframe o/s's ever) used a single byte for storing extent
>>>>number. Thus you were limited to 255 extents. (wasn't this also the case
>>>>with Oracle extents a few versions ago?)
>>>>
>>>>Using DOS old FAT16 filesystem is no different. The File Allocation Table
>>>>has also size restrictions. Thus, a completed path of a subdirectory can
>>>>only be (if I recall correctly) also 255-256 characters in total. When you
>>>>reached that limit, you can not create any more subdirectories.
>>>>
>>>>Okay, now for ionodes and Unix. A file is represented by a structure called
>>>>an inode (similar to a FAT entry).
>>>>
>>>>Each inode contains stuff like file type, access rights, timestamps, size,
>>>>pointers to data blocks, and so on. A bunch of data blocks make up a file.
>>>>Their addresses are stored in that file's inode.
>>>>
>>>>An ionode is of a certain size. Thus, you are limited to the number of data
>>>>block pointers (or addresses) you can store in the ionode of a file.
>>>>
>>>>Here are a table listing Unix filesystems used by Linux through the years:
>>>> Minix ext ext2
>>>>Max fileystem size 64MB 2GB 4TB
>>>>Max file size 64MB 2GB 2GB
>>>>
>>>>Because operating systems are closely tied to specific filesystems (often
>>>>only running on a single specific filesystem), filesystem limitation such
>>>>as the 2GB filesize limit is seen as an operating system issue. Which is
>>>>not really the case as that limitation belongs solely to the filesystem.
>>>>
>>>>--
>>>>Billy
>>>
>>>
>>>You are correct but I don't see the separation as clearly as you do. If an O/S
>>>doesn't support a file system it is the O/S that is the issue.
>>>
>>>In the case of some O/Ss they default to 2GB files and default parameters in the
>>>O/S can be changed to allow larger files. The makes it look, again, like the O/S
>>>to me.
>>>
>>>Daniel Morgan
>>>
>>
>>First of all - Billy is right in stating it is a file system issue, not
>>OS. I must become more precise...
>>
>>And Daniel: what about Microsoft's 536MB "barrier", 2GB, 4GB, ...?
>>Doesn't MS have DOS (in two flavors, if I may believe the Linux
>>Installer/Disk Druid: FAT12/FAT16), NTFS, FAT32? Afaik, you can
>>still install Win2K on a DOS16 partition - it will effectively
>>limit your file (and partition!) sizes, but you can. You can also
>>migrate to NTFS of FAT32, allowing for much larger files/partitions.
>>
>>OS/2 could use HPFS (superior to NTFS, in my opinion), or FAT.
>>
>>I remember burning a special CD off the standard NT Server CD, with
>>drivers of sp4 (iirc), just because that allowed you to install
>>NT in a larger-than-2GB partition. Until sp4, you could not create
>>a boot partition, larger than 2GB.
>>
>>Don't many of today's Linux distro's give you a choice of ext2,
>>ext3, reiserfs, journalled rfs, or a combination of all of the above?
>>
>>If you still want to call it an OS issue, fine with me, but I hope
>>I have made it clear with the above examples, that it is more of
>>a file system issue.
>>OS's (even MS!) support multiple file systems; it's up to the user
>>to decide what's best.
>>--
>>Regards, Frank van Bortel
>
>
> If you limit the discussion to Intel boxes ... but how about Sun, HP, and IBM (AIX)
> which is where most of the serious Oracle work is done?
>
> Daniel Morgan
>
I am not that knowledgeable about the file systems used on those
platforms. I know some Unix to realize there's raw IO and cooked IO.
And not to like HP - you can still not read a Rockrigde CD.
It was just that I knew some examples of Operating Systems,
that supported different file systems. And it happened to be
Intel hardware. Yeah, well, sorry about that.
I am sure Sun, IBM and HP have (had) their different file systems,
on their hardware platforms, too. I just don't know the examples.
'nuff said
--
Regards, Frank van Bortel
Received on Sun Feb 16 2003 - 13:58:57 CST
