Re: [Moosefs-users] Chunks

[Thomas S H. <tha...@gm...>]

Over ext4? moosefs is a different storage layer than ext4, do you mean xfs
over ext4? ext3 over ext4?

On Wed, Mar 2, 2011 at 10:30 AM, Steve <st...@bo...> wrote:

>
> What is the feature in moosefs that makes you choose it over say ext4 ?
>
>
>
> I'm not understanding this yet!
>
>
>
> -------Original Message-------
>
>
>
> From: Michal Borychowski
>
> Date: 02/03/2011 16:08:20
>
> To: 'Heiko Schröter'
>
> Cc: 'moosefs-users'
>
> Subject: Re: [Moosefs-users] Chunks
>
>
>
> Hi Heiko!
>
>
>
> We undestand your point and can see that using RAID6 + goal=1 is a little
>
> bit more economical than RAW HDD + goal=2 but this is not a huge difference
>
> as you still need some disks for the RAID6.
>
>
>
> The main purpose of MooseFS system is security not the space savings. And
>
> solution with RAID6 is not that secure. We generally advise not to use any
>
> RAIDs and using at least goal=2.
>
>
>
> Module responsible for rebalancing chunks operates on chunks (independently
>
> of the files). Each chunk is treated individually while making different
>
> operations. So the requested change is not just a matter of providing a
>
> simple patch, it would be a change in the "philosophy" of the system and
>
> unfortunately won't be possible.
>
>
>
>
>
> Kind regards
>
> Michal
>
>
>
>
>
> -----Original Message-----
>
> From: Heiko Schröter [mailto:sch...@iu...]
>
> Sent: Monday, February 28, 2011 4:13 PM
>
> To: mic...@ge...
>
> Subject: Chunks
>
>
>
> Hi Michael,
>
>
>
> sorry for seeing your post to the list too late before posting my
>
> screenshots.
>
> I can see your point, but to us it would be very important to have a
>
> "chunkabilty" or striping in other fs of one.
>
>
>
> The reason:
>
>
>
> We receive a lot of large satellite data files per day. (400MB to 2GB per
>
> file).
>
> The storage space is limited (because of the governmental funding), so we
>
> need to keep risks to a certain minimum with the ressources given.
>
>
>
> We are running Hardware raid6 on our chunkservers. So there is some safety
>
> margin here.
>
>
>
> But we need to make sure that in case of a total breakdown of a chunkserver
>
> only some files are lost to 100%, and not all files beeing damaged to a
>
> certain extend and therefore irrecoverable.
>
>
>
> So if I could be of any help testing a patch I would very much appreciate
>
> it.
>
>
>
> Thanks for your time looking into this.
>
>
>
> Regards
>
> Heiko
>
>
>
>
>
>
>
>
>
>
>
>
>
> Hi Heiko!
>
>
>
> You are definitely right! I made a mistake writing all chunks of the file
>
> with goal=1 would reside just on one chunkserver. Each chunk of the file
>
> would go (more or less by random) to different chunkservers.
>
>
>
> On the other hand we again focus on the point that using goal=1 is almost
>
> useless. Unless these are some temporary, unimportant files. The
> expectation
>
>
> of distributed file system is to keep at least two copies of the file :)
>
>
>
> Thank you for being conscious :)
>
>
>
>
>
>
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