set_layout

set_layout

[xinren]

All,

I try to use cephfs to set up 
various parameters, such as 

cephfs /cephdir set_layout -s 8388608 -c 1 -u 8388608 -o 1

In this case, the "preferred osd" will be 1. I then copy files to /cephdir. I 
found that stripe_unit is 8MByte. However, files are copies to different OSDs (I 
have 4 OSDs). Is there any way that I copy a file to a designate OSD? Thanks in 
advance.

Regards

Xinren

Re: set_layout

[Tommi Virtanen]

On Fri, Apr 27, 2012 at 10:25, xinren <tntinfo@hotmail.com> wrote:
> All,
>
> I try to use cephfs to set up
> various parameters, such as
>
> cephfs /cephdir set_layout -s 8388608 -c 1 -u 8388608 -o 1
>
> In this case, the "preferred osd" will be 1. I then copy files to /cephdir. I
> found that stripe_unit is 8MByte. However, files are copies to different OSDs (I
> have 4 OSDs). Is there any way that I copy a file to a designate OSD? Thanks in
> advance.

The "local PGs" feature used by -o is deprecated and removed
(depending on the release).

Experience with the feature showed that it did not behave well, and we
currently consider trying to manually manage data allocations to osds
a bad idea.

If you want to manage how your data is located and replicated, you are
better off using pools with custom crushmap rules. This allows for
placement policies that are still flexible enough to handle osd
failures and balancing.

Re: set_layout

[xinren]

Thanks for the info. I will look at "custom crushmap rules".