RE: How to make Linux scale up WRT bandwidth and size?

Jeremy Fitzhardinge (jeremy@goop.org)
Thu, 29 Apr 1999 12:29:20 -0700 (PDT)

On 29-Apr-99 David Kastrup wrote:
> File size: the ext2 file system tops out at 2GB file size, which is
> sufficient only for very short sequences (about two minutes).
> Something like 10GB would be more appropriate. For handling of the
> sequences *after* recording at the latest, we need to put them on
> files. Partitions are not flexible enough. So probably we need to
> use a non-native file system for this, like NTFS.

The limit is in the VFS layer on 32-bit CPUs, so switching filesystems won't
help. Ext2 and the VFS do support large files on 64 bit CPUs, so you're in
luck.

> File access speed during recording: we could probably get around this
> one by not memory-mapping a file, but a partition (or its RAID
> equivalent). It would probably still be a large waste of resources
> not to be able to be using a raw device for this.

You can't mmap block devices. I don't think avoiding the filesystem will help
particularly, though you could avoid some filesystem overhead in the real-time
path by preallocating the file.

J

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