Re: Suggestion for Linux 2.3

bofh@snoopy.virtual.net.au
Tue, 07 Jan 97 21:43:58 +1000

>> This one's a tricky one, but it would be extremely nice for people, such
>> as ISPs, who are likely to want to add, upgrade, etc. hard drives on a
>> comparitively frequent basis: something like Digital's AdvFS.
>[output from Digital "df" command deleted for brevity...]B
>> Notice that the user_domain is mounted on three separate points, for three
>> separate functions. Adding a partition to a domain increases its size;
>> removing one reduces it. The nice thing is that if you add a new hard drive,
>> add it to a domain, and remove the original partitions from the domain, all
>> the contents of the domain are moved to the remaining drive, relatively
>> transparently.
>>
>> AdvFS is available under Digital Unix; 'twould be very nice to have, IMO.
>> (I'd do work on it, but I don't have the time, nor the technical knowledge,
>> to pull it off. :-( ) I can't see it happening before 2.3, though.

>This is similar to IBM AIX and its JFS (Journaled File System). When a disk
>is added to the system, you have to add the physical disk into a "Volume
>Group". This volume group (1 or more physical drives) can then be split up
>into multiple file systems and each filesystem can be mounted individually.
>When the drive is added into the volume group (VG), it is divided up into
>Physical Partitions (PP) of normally 4MB. These PPs can then be added to any
>of the filesystems in that VG. Therefore, if you need to make a couple
>filesystems larger, you don't have to repartition the HD and/or shuffle mount
>points, all you do is add a drive to the volume group and disperse the 4MB
>PPs to the required filesystems.

>Anyone want to work on this for Linux? I don't have the time to be a lead
>person, but this looks like it would integrate well with the MD driver (Multi
>Disk)... Might be a big step for ext2 -- anything going on with that
>project?

From what I know of the IBM JFS it is not nearly as capable as the DEC ADVFS.
ADVFS supports adding and removing partitions dynamically while JFS AFAIK only
supports adding them dynamically (and removing them is as difficult as moving
file systems around on E2FS is). ADVFS also has other features such as it's
snap-shot backup.

I have started a project to develop a free filing system to support all
features that are in the DEC ADVFS, and if possible the features that DEC plans
for the next version of ADVFS (as listed on their web page). Currently I am
the lead person for this as I haven't found anyone else who's better qualified
and willing to take the job. I am looking for a host for a mailing list (as
I'm having problems with my PERL setup and can't get it to work properly -
alternatively if a Majordomo/PERL expert could give me some tips on getting a
mailing list going then it would be greatly appreciated).

If you are interested in joining the project or are able to help with a
mailing list then please contact me by sending mail to
rjc@snoopy.virtual.net.au (an address that I use for mail which is of higher
priority than typical mailing list stuff).

Russell Coker