[9fans] disk/prep partitioning issue

[9fans] disk/prep partitioning issue

[Marco Feichtinger]

I have a behaviour from disk/prep I do not understand.
I want to setup a partition table on a venti server as follows.

%disk/prep /dev/sdE0/plan9
        empty                             0 204800              (204800 sectors, 100.00 MB)
        nvram                   204800 204801           (1 sectors, 512 B )
        empty                   204801 204816           (15 sectors, 7.50 KB)
        arenas0                 204816 209920016                (209715200 sectors, 100.00 GB)
        isect0            209920016 220405776           (10485760   sectors, 5.00 GB)
        arenas1           220405776 430120976           (209715200 sectors, 100.00 GB)
        isect1            430120976 440606736           (10485760   sectors, 5.00 GB)
        arenas2           440606736 650321936           (209715200 sectors, 100.00 GB)
        isect2            650321936 660807696           (10485760   sectors, 5.00 GB)
        arenas3           660807696 870522896           (209715200 sectors, 100.00 GB)
        isect3            870522896 881008656           (10485760   sectors, 5.00 GB)
        arenas4           881008656 1090723856  (209715200 sectors, 100.00 GB)
        isect4          1090723856 1101209616   10485760   sectors,  5.00 GB)
        arenas5         1101209616 1310924816   (209715200 sectors, 100.00 GB)
        isect5          1310924816 1321410576   (10485760   sectors,  5.00 GB)
        arenas6         1321410576 1531125776   (209715200 sectors, 100.00 GB)
        isect6          1531125776 1541611536   (10485760   sectors, 5.00 GB)
        arenas7         1541611536 1751326736   (209715200 sectors, 100.00 GB)
        isect7          1751326736 1761812496   (10485760   sectors, 5.00 GB)
        bloom           1761812496 1762861072   (1048576     sectors, 512.00 MB)
        empty           1762861072 1875379842   (112518770 sectors, 53.65 GB)

Now if I write the partition to disk, and exit the prep,
the bloom, isect7 and arenas7 partition are gone.

If I prep the disk again it shows following

%disk/prep /dev/sdE0/plan9
        empty                             0 204800              (204800 sectors, 100.00 MB)
        nvram                   204800 204801           (1 sectors, 512 B )
        empty                   204801 204816           (15 sectors, 7.50 KB)
        arenas0                 204816 209920016                (209715200 sectors, 100.00 GB)
        isect0            209920016 220405776           (10485760   sectors, 5.00 GB)
        arenas1           220405776 430120976           (209715200 sectors, 100.00 GB)
        isect1            430120976 440606736           (10485760   sectors, 5.00 GB)
        arenas2           440606736 650321936           (209715200 sectors, 100.00 GB)
        isect2            650321936 660807696           (10485760   sectors, 5.00 GB)
        arenas3           660807696 870522896           (209715200 sectors, 100.00 GB)
        isect3            870522896 881008656           (10485760   sectors, 5.00 GB)
        arenas4           881008656 1090723856  (209715200 sectors, 100.00 GB)
        isect4          1090723856 1101209616   (10485760   sectors, 5.00 GB)
        arenas5         1101209616 1310924816   (209715200 sectors, 100.00 GB)
        isect5          1310924816 1321410576   (10485760   sectors, 5.00 GB)
        arenas6         1321410576 1531125776   (209715200 sectors, 100.00 GB)
        isect6          1531125776 1541611536   (10485760   sectors, 5.00 GB)
        empty           1541611536 1875379842   (333768306 sectors, 159.15 GB)

What's causing that?

-marco


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Re: [9fans] disk/prep partitioning issue

[Richard Miller]

> ...
> the bloom, isect7 and arenas7 partition are gone.
> ...
> What's causing that?

The partition table has to fit in one disk sector. Has yours
got bigger than 512 bytes? You might have to split it up
into two fdisk partitions, or shorten some names.

Try 'disk/prep -p /dev/sdE0/plan9 | wc -c'


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Re: [9fans] disk/prep partitioning issue

[Richard Miller]

I said:
> You might have to split it up
> into two fdisk partitions, or shorten some names.

Actually, shortening names isn't likely to help much.

If you're setting up a new venti, not expanding an
existing one, could you make the arena partitions
fewer and larger? The original idea behind limiting
arena size was so that they could be conveniently
backed up onto optical media, but I suspect nobody
does that any more.  Nowadays large arenas can be
backed up onto a big USB flash drive, or onto another
venti server.


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Re: [9fans] disk/prep partitioning issue

[Marco Feichtinger]

> Try 'disk/prep -p /dev/sdE0/plan9 | wc -c'

Tried it; output:
        syntax error reading partition
                488

So my partition count is too much, correct?


> The original idea behind limiting
> arena size was so that they could be conveniently
> backed up onto optical media, but I suspect nobody
> does that any more.  

That was the plan.
Now I might change that.

-marco


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Re: [9fans] disk/prep partitioning issue

[Richard Miller]

> Tried it; output:
>         syntax error reading partition
>                 488
> 
> So my partition count is too much, correct?

Correct. The last line has been truncated at the end of the block
so it has no newline, which is a syntax error.

It's ok to use fdisk to create more than one plan9 partition on a disk.
They'll appear as /dev/sd*/plan9, /dev/sd*/plan9.1 etc. Then you can
use prep to put some of your arenas on each plan9 partition, to avoid
overflowing the partition tables.


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Re: [9fans] disk/prep partitioning issue

[Marco Feichtinger]

Okey, thanks

-marco


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[9fans] boot order on separate venti/fossil machines

[Marco Feichtinger]

I am curios.
In an environment where you have separate machines for fossil and venti,
do you boot fossil first, and let venti pxe boot over it,
or do you boot venti first, with a small, local, fossil partition?

-marco

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Re: [9fans] boot order on separate venti/fossil machines

[Charles Forsyth]

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Fossil once attached to venti can't serve without it, so venti must arrive
first.
My machine is fossil+venti, so not quite what you asked about, but the
mechanism would
be similar. The server boots the kernel from 9fat. (If I wanted to pxe boot
the venti,
I could push the boot server problem back to a boot server, perhaps the
auth server.)
The kernel uses configuration pcfs, which contains enough in bootdir to
start and run fossil,
which checks $venti (set in plan9.ini) to see if it should run that first,
if local. If venti isn't
local, it sets up the network so fossil can dial it.
/sys/src/9/boot/local.c organises that. I don't think a configuration is
provided
that starts just venti, but some of the pc* configurations in /sys/src/9/pc
hint at ways to
make various custom systems.

(9front's /sys/src/9/boot use rc scripts, which is much easier to change,
but it doesn't provide fossil at all.)

On Sat, 20 Apr 2024 at 08:21, Marco Feichtinger <marco@germteig.com> wrote:

> I am curios.
> In an environment where you have separate machines for fossil and venti,
> do you boot fossil first, and let venti pxe boot over it,
> or do you boot venti first, with a small, local, fossil partition?
> 
> -marco

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