Subject Re: [firebird-support] Re: Database Size
Author Helen Borrie
At 05:39 AM 6/07/2007, you wrote:
>Speaking to the limitations of file system sizes alone:
>FAT12 has a 32MB file size limit
>FAT16 has a 2GB file size limit

Only if it was created on NT 3 or higher.

>FAT32 has a 4GB file size limit

- no, 2 Gb, unless it was created on NT 5 or higher.

>NTFS has a 16EiB file size limit

Unless the NTFS partition was created on NT 4. Then, the file size
limit is 4 Gb, even if you subsequently updated the OS to NT 5 or higher.

>EXT3 has a 2TB file size limit

Not necessarily. File size limits on Linux (ext2/ext3 or reiserFS)
depend on the block size that the kernel was compiled with, so it's
literally customisable if you roll your own and build-specific if you
use others' binaries.

>I believe the "Firebird limit" on database size depends on the page
>size set when you create the database.

No. Firebird just keeps on requesting disk storage it needs, in
page-sized blocks, until the filesystem says "No more".

>I definitely have some Firebird databases that are over 2GB.

Under 2 Gb would be a pretty small database. :-) Regardless of file
size limits imposed by the filesystem, Firebird has always been able
to spread a database over multiple files (and thus, different storage
devices). To the server, it is all one logical file.

>I've also read that with an 8K page size you can have BLOB's up to
>32GB, so that would imply to me that databases could be at least that
>large. Perhaps someone can provide you with an exact answer from the
>Firebird side.

Again, only the filesystem limits the size of a blob. Of course,
given that one usually stores data with the intention of retrieving
it, one has to apply some common sense.

>However, do consider the info above when choosing a file system.

Understanding the limits of the file system is always an issue for
deploying databases. A trap to watch for in a lot of site situations
is that operating systems were upgraded without upgrading the old
filesystem. Some of those hard disks out there are museum
pieces. Often, the only decent hard disk in the whole organisation
is the one on the boss's desktop that he switches on once a day to
read his email.

If we care about the safety, performance and security of the systems
we install, we owe it to our customers to be extremely picky about
the storage they're going to put them onto. It's all very well for
us to crow about Firebird's ability to function on any old clunker -
it's a total anachronism, IMO. Firebird will be just as dead as
anything else when that 1996-vintage 2.8Krpm hard disk decides it is
time to plod no more.