[9fans] fs(3) for pseudo partitions

[9fans] fs(3) for pseudo partitions

[Akshat Kumar]

For AoE reasons, I need to combine
a mirror (of a partition of a disk and
a whole disk) with another partition
of a disk, in a way that the combination
looks like a disk in itself.

Has anyone tried such a thing with fs(3)?
I have a mirror:

mirror m0 /dev/sdD1/data /dev/sdC0/worm

at /dev/fs/m0, and what I would like is
a new pseudo device in fs(3) that joins
/dev/fs/m0 and /dev/sdC0/kcache. But
not simply as a `cat' of these two files,
rather so that the resulting data file
has the two as partitions.

This way I don't need a ton of NICs and
`vblade' instances for each drive/partition
that I want to serve to my ken fs server.


Thanks,
ak

Re: [9fans] fs(3) for pseudo partitions

[erik quanstrom]

On Sun Jul 10 22:58:01 EDT 2011, akumar@mail.nanosouffle.net wrote:
> For AoE reasons, I need to combine
> a mirror (of a partition of a disk and
> a whole disk) with another partition
> of a disk, in a way that the combination
> looks like a disk in itself.
>
> Has anyone tried such a thing with fs(3)?
> I have a mirror:
>
> mirror m0 /dev/sdD1/data /dev/sdC0/worm
>
> at /dev/fs/m0, and what I would like is
> a new pseudo device in fs(3) that joins
> /dev/fs/m0 and /dev/sdC0/kcache. But
> not simply as a `cat' of these two files,
> rather so that the resulting data file
> has the two as partitions.
>
> This way I don't need a ton of NICs and
> `vblade' instances for each drive/partition
> that I want to serve to my ken fs server.

there are several simple options
- write a little sd driver.  see sdloop(3) for
a prototype.

- modify vblade to serve multiple luns.

- erik

Re: [9fans] fs(3) for pseudo partitions

[Akshat Kumar]

On Sun, Jul 10, 2011 at 8:05 PM, erik quanstrom <quanstro@quanstro.net> wrote:
> there are several simple options
> - write a little sd driver.  see sdloop(3) for
> a prototype.

Ah, so such a thing can't be done simply
with some fs(3) configuration?

The sd driver would concatenate the specified
list of files, and keep in the header, some
partition lines, in the vein of sd(3) data files?

>
> - modify vblade to serve multiple luns.
>

Is there any reason you decided against this
in the past? Some drawbacks?


Thanks,
ak

Re: [9fans] fs(3) for pseudo partitions

[erik quanstrom]

> >
> > - modify vblade to serve multiple luns.
> >
>
> Is there any reason you decided against this
> in the past? Some drawbacks?

vblade is a toy target.  i wrote it in an evening to
demonstrate that it just wasn't that hard.  it's not
ment to be performant or featurefull.

- erik