RAID VFS module SoC project

[Gerald (Jerry) Carter]

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Copying back on the samba-techincal list...

Ming Wong wrote:

> Yeah, I agree. Implementing a directory tree stuff was what 
> I first have been thinking over the weekend. :)
> 
> How do you reckon we can achieve that?
> I thought of a couple of ways to approach this problem:
> 1. Let the file system handle the tree structure (On system starts,
> structures on different disks are examined but slower.)
> 2. Build a tree structure internally in the VFS module (Dump this
> structure into a file on the corresponding disk.)

If I understand your comment correctly, I think it's safer
to start with the simplier solution.  Let the file system
handle the files and not try to implement another block type
protocol on top of the fs.  The VFS module will then only
have to handle the naming schemes.

>> Building the initial mirror is a little bit more work.
>> I'd accept using rsync for establishing the initial
>> mirror (outside of smbd).  If we can be more clever
>> later on, that good.  But at least we can get started.
> 
> Yep, I reckon rsync is good enough for now. But I 
> was thinking to implement something myself to achieve
> that. I was thinking that building the initial mirror
> might take quite a bit of time. So if we could write
> our component to handle that, we could keep samba online 
> whilst the system is still building the mirror. (This
> may require the later approach suggested in implementing
> the directory tree, cause then we can update the directory
> tree in a more efficient fashion whenever any
> changes are made to the primary disk. )

I'm not sure how easy this would be to do in Samba 3,
but I can think of a few possible ways.  If you can work
one out, that sounds good.  Just remember that it's a
secondary priority behind having a working module :-)

>> We can look at striping later.  Level 1 probably makes
>> more  sense initially.  Raid 0+1 might be interesting.
>> I'm not how to really leverage the advantages of RAID 5.
> 
> Agreed.
>
> So from here on, I'm gonna start writing the directory 
> tree mirroring module first. Actually, I started planning on
> a bit of stripping stuff. (I was designing the indexing
> of distribution of files across disks before. ) But that's
> ok, after RAID 1 is down, we can head back down to
> the stripping. :)

ok.  Sounds good.






cheers, jerry
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