Messages in this thread | | | Date | Wed, 27 Nov 1996 15:55:17 -0800 (PST) | From | David McIntyre <> | Subject | Re: Union file system |
| |
On Wed, 27 Nov 1996, D. Chiodo wrote:
> On Wed, 27 Nov 1996, Keith Owens wrote: > > > Does anybody know of a union file system for Linux? Alternatively any > > writeups on why it is/is not a good idea? > > > > Looking for a way to take multiple levels of data, some on cdrom, some on > > network, some on disk and make it look like a single level. All updates > > should be written to the top level. > > Symlinks? Mount all the cd, network, disk, etc, then make symlinks from > whereyou want you everything to appear to wherever the appropriate files > are...
Symlinks have the disadvantage of being "seperate" filesystems. The idea of a union filesystem is to make all drive space on all drives appear as a contiguous block. Therefor, it would be harder to run out of space on one of the component filesystems. For example, if you mount /home on a 1gig drive and you have 900meg used on it, you would be unable to untar a 200meg file, even if you had 3gig on the / partition. A union filesystem would show that you had the available free space of all free space on all physical devices. This is possible to do in Novell with a base system. It has a couple of quirks which only show up in unusual situations. In Novell, you can't split a single file across physical devices. It just begins on the next device if a file is about to overrun one device. This is usually not a factor unless you are working with a HUGE file, like a big database. But then, if this were our application, we'd buy a drive large enough to support the file, wouldn't we? :)
----------------------------------------------------------------------------- David McIntyre (in order) -> | (1) plugh@best.com | The geeks Linux Powered | (2) davidm@fsc.fujitsu.com | shall inherit PGP key available: | (3) plugh@webpros.com | the earth. finger plugh@plugh.vip.best.com | (4) plugh@mailstop.com |
| |