[9fans] 9load and 9fat

[9fans] 9load and 9fat

[Vester Thacker]

I know that under Plan 9 the 9fat directory is a FAT file system.
I know that 9load accesses the 9fat directory for plan9.ini and
kernels. If 9load were to be replaced with a means for Plan 9 to
be booted without 9load, would there be a need to have the 9fat
directory? Or would there be any need for a FAT filesystem in
Plan 9?  I'm asking this after reading prep(8) and Ron Minnich's
earlier post in 9fans.

-- Vester Thacker

Re: [9fans] 9load and 9fat

[Lucio De Re]

On Sun, Sep 28, 2003 at 04:55:48PM +0900, Vester Thacker wrote:
>
> I know that under Plan 9 the 9fat directory is a FAT file system.
> I know that 9load accesses the 9fat directory for plan9.ini and
> kernels. If 9load were to be replaced with a means for Plan 9 to
> be booted without 9load, would there be a need to have the 9fat
> directory? Or would there be any need for a FAT filesystem in
> Plan 9?  I'm asking this after reading prep(8) and Ron Minnich's
> earlier post in 9fans.
>
I think the more recent 9loads can read the Plan 9 filesystem so,
no, there is no need for a FAT partition, although the chicken and
egg problem of where to find plan9.ini is still haunting Plan 9
boot.

++L

Re: [9fans] 9load and 9fat

[Vester Thacker]

On Sun, Sep 28, 2003 at 10:15:06AM +0200, Lucio De Re wrote:
>
> I think the more recent 9loads can read the Plan 9 filesystem so,
> no, there is no need for a FAT partition, although the chicken and
> egg problem of where to find plan9.ini is still haunting Plan 9
> boot.

I'd suggest /sys/boot for the files, but I was really just
interested in the relationship between 9fat, the FAT file
system, and 9load. Thanks for clearing this up.

-- Vester Thacker

Re: [9fans] 9load and 9fat

[Russ Cox]

> I think the more recent 9loads can read the Plan 9 filesystem so,
> no, there is no need for a FAT partition, although the chicken and
> egg problem of where to find plan9.ini is still haunting Plan 9
> boot.

Only if your Plan 9 file system is the now-obsolete kfs.
Reading a kernel from a fossil+venti file system is quite
a lot more code, so it seems 9fat is going to stay for
a bit longer.  Sadly.

Russ

Re: [9fans] 9load and 9fat

[Lucio De Re]

On Sun, Sep 28, 2003 at 08:12:55AM -0400, Russ Cox wrote:
>
> Only if your Plan 9 file system is the now-obsolete kfs.
> Reading a kernel from a fossil+venti file system is quite
> a lot more code, so it seems 9fat is going to stay for
> a bit longer.  Sadly.
>
There's always the floppy drive, although that may cost a little
more than 10MB of hard disk.  Nice thing about the floppy is that
the kernel can be compiled without support for it, so it remains
secure against alterations.

++L

Re: [9fans] 9load and 9fat

[Richard Miller]

> Only if your Plan 9 file system is the now-obsolete kfs.

Is kfs really obsolete now?  What about a laptop which is normally
used standalone "on the road" and occasionally synchronised with
the home fileserver?  Is kfs still more suited to that environment,
or would it be better to configure a fossil without venti backing?

-- Richard

Re: [9fans] 9load and 9fat

[Fco.J.Ballesteros]

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My laptop is running a fossil, and the nice thing is that
you get snapshots although I don't archive them. I use
rm without thinking twice.

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From: Richard Miller <miller@hamnavoe.demon.co.uk>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] 9load and 9fat
Date: Wed, 1 Oct 2003 16:11:56 +0100
Message-ID: <b78586e0d4f360e23f00eeb9d45d7bbb@hamnavoe.com>

> Only if your Plan 9 file system is the now-obsolete kfs.

Is kfs really obsolete now?  What about a laptop which is normally
used standalone "on the road" and occasionally synchronised with
the home fileserver?  Is kfs still more suited to that environment,
or would it be better to configure a fossil without venti backing?

-- Richard

Re: [9fans] 9load and 9fat

[Russ Cox]

> Is kfs really obsolete now?  What about a laptop which is normally
> used standalone "on the road" and occasionally synchronised with
> the home fileserver?  Is kfs still more suited to that environment,
> or would it be better to configure a fossil without venti backing?

If I were installing a new system, I would run fossil.
If you run without venti backing you can still keep
daily dumps (in /n/snap) and retire them as you need
the disk space back.  Even without any of that, fossil
is much more resilient to being turned off abruptly,
and it supports long file names.  If you run fossil+venti,
then it takes absolutely forever to fill up even a few
gigabytes of Venti, and it's easy to back up the laptop
by simply backing up the Venti server to another Venti
server, incrementally.

Re: [9fans] 9load and 9fat

[ron minnich]

w.r.t fossil and configuration a machine.

Say I have a 4 gB partition disk. Do I make the whole disk 'plan9' and put
(e.g.) fossil on 2 gB, venti on 2 GB? Or do I make 'plan9' 2 gB and plan
to put venti on the other 2 gB?

ron

Re: [9fans] 9load and 9fat

[Russ Cox]

> Say I have a 4 gB partition disk. Do I make the whole disk 'plan9' and put
> (e.g.) fossil on 2 gB, venti on 2 GB? Or do I make 'plan9' 2 gB and plan
> to put venti on the other 2 gB?

you can do whatever you want.  i find it nicer to make plan9 the whole
disk because then i can use arbitrary names for the subpartitions.

Re: [9fans] 9load and 9fat

[Richard Miller]

> If I were installing a new system, I would run fossil.
> [... good reasons deleted]

OK, I'm sold.  But I find the concept of backing up a
venti server onto another venti server makes my brain hurt.

- if you lost the venti partition on the laptop, how would
  you restore it from the other server?
- looking at /sys/src/cmd/venti/backup.example why do you
  have to subtract blockSize from the arena offset?

-- Richard

Re: [9fans] 9load and 9fat

[Fco.J.Ballesteros]

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IMHO, if you run fossil in your laptop you usually make
it archive on your venti file server, which is supossed
to be reliable and backed up (eg. by using devfs).

If you run both a laptop and a real file server, I've
found it useful to keep a fossil with just snapshots
(no archives) in the laptop and keep it replica(1)ted
from your real file server, that makes archives too.

hth

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From: Richard Miller <miller@hamnavoe.demon.co.uk>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] 9load and 9fat
Date: Wed, 1 Oct 2003 17:38:23 +0100
Message-ID: <3bf4d3f39cb2ab57f509a57a62f4d6c6@hamnavoe.com>

> If I were installing a new system, I would run fossil.
> [... good reasons deleted]

OK, I'm sold.  But I find the concept of backing up a
venti server onto another venti server makes my brain hurt.

- if you lost the venti partition on the laptop, how would
  you restore it from the other server?
- looking at /sys/src/cmd/venti/backup.example why do you
  have to subtract blockSize from the arena offset?

-- Richard

Re: [9fans] 9load and 9fat

[Russ Cox]

> - if you lost the venti partition on the laptop, how would
>   you restore it from the other server?

you'd venti/copy the latest root hash you had, and that
would get you the entire history of your laptop fossil.

> - looking at /sys/src/cmd/venti/backup.example why do you
>   have to subtract blockSize from the arena offset?

because the code is sloppy about exactly what
the arena offset means.  in the c code the arena
base typically points just after the header, but
when you set up an arena by pointing venti at a
particular location on disk, you have to give it
the pointer to the beginning of the header.

russ

Re: [9fans] 9load and 9fat

[Richard Miller]

>> - if you lost the venti partition on the laptop, how would
>>   you restore it from the other server?
>
> you'd venti/copy the latest root hash you had, and that
> would get you the entire history of your laptop fossil.

Any sufficiently advanced technology is indistinguishable
from magic ...  very nice.

>> - looking at /sys/src/cmd/venti/backup.example why do you
>>   have to subtract blockSize from the arena offset?
>
> ...  in the c code the arena
> base typically points just after the header ...

Got it.  Unfortunately the example script doesn't work for me
because my arena blocksize is not the same as the index blocksize.
That's what I get for not sticking to default values.

-- Richard

Re: [9fans] 9load and 9fat

[boyd, rounin]

> Is kfs really obsolete now?  What about a laptop which is normally
> used standalone "on the road" and occasionally synchronised with
> the home fileserver?  Is kfs still more suited to that environment,
> or would it be better to configure a fossil without venti backing?

i guess kfs was a jump start.  a long time ago i was talking to
honeyman about how he could sync with AFS once he got off
the road and back 'home'.

Re: [9fans] 9load and 9fat

[boyd, rounin]

not really.  russ explained it pretty well:

    http://www.insultant.net/repo/plan9/usbflop.html