Re: [9fans] Petabytes on a budget: JBODs + Linux + JFS

[Jack Norton <jack@0x6a.com>]

erik quanstrom wrote:
>> So what about having venti on an AoE device, and fossil on a local drive
>> (say an ssd even)?
>>
>
> sure.  we keep the cache on the coraid sr1521 as well.
>
>
>> How would you handle (or: how would venti handle), a
>> resize of the AoE device?
>>
>
> that would depend on the device structure of ken's fs.
> as long as you don't use the pseudo-worm device, it wouldn't
> care.  the worm would simply grow.  if you use the pseudo-worm
> device (f), changing the size of the device would fail since
> the written bitmap is at a fixed offset from the end of the
> device.  and if you try to read an unwritten block, the f
> panics the file server.  i stopped using the f device.
>
> - erik
>
>
I am going to try my hands at beating a dead horse:)
So when you create a Venti volume, it basically writes '0's' to all the
blocks of the underlying device right?  If I put a venti volume on a AoE
device which is a linux raid5, using normal desktop sata drives, what
are my chances of a successful completion of the venti formating (let's
say 1TB raw size)?   Have you ever encountered such problems, or are you
using more robust hardware?
I ask because I have in the past, failed a somewhat-used sata drive
while creating a venti volume (it subsequently created i/o errors on
every os I used on it, although it limped along).  I must say it is
quite a brutal process, creating venti (at least I get that impression
from the times I have done it in the past).
If linux is my raid controller, I know that it is _very_ picky about how
long a drive takes to respond and will fail a drive if it has to wait
too long.

By the way I am currently buying a few pieces of cheap hardware to
implement my own diskless fileserver.  Should be ready to go in about a
couple of weeks.

-Jack