[lustre-discuss] Supporting more than 4 parity OST’s

[Stepan Beskrovnyy]

Hello everyone!

In my diploma project I use WIP EC branch, and I need to have more parity
oss’s than current supported. (More than 4, in my case - 8).

I use cluster topology with 24 oss’s laid on 6 servers, 4 oss’s per node
each. (Due to performance issues I cant use less, I did a topic about
client performance limitation, because of it I try to avoid this by adding
oss’s). I want to lose 2 of 6 nodes(requirement from the professor). In
this case I need 8 parity oss’s with scheme n+8(16+8 for example)

I found a way to use custom EC layouts with —ec-expert flag and set 16+8
layout. Then I killed 8 random oss’s and mirror resync funtion falls with
error “resource temporary unavailable”.

Is there any way to use layouts with more than 4 oss’s and use resync on
them? I know, that EC is very WIP branch, but is anyone knows or tested
this feature with this layouts yet ? I’m ready to use at my own risk and
will fix bugs if I would see some, but help with the way how to set up 16+8
layout and rebuild file on it.

Thanks,
Stepan
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