* raid40?
@ 2011-04-16 1:10 Fyodor Ustinov
2011-04-16 1:13 ` raid40? Gregory Farnum
0 siblings, 1 reply; 2+ messages in thread
From: Fyodor Ustinov @ 2011-04-16 1:10 UTC (permalink / raw)
To: ceph-devel
Hi.
Looking the sources I noticed that the "rule" in CRUSH may be type "raid4".
Because of this, I have a question: Is it possible to organize the 20
OSD servers in the scheme 4 * (4+1)? I.e. like a stripe from 4 of raid4
sets?
Plain "replication level = 2" is too expensive by "used space".
WBR,
Fyodor.
^ permalink raw reply [flat|nested] 2+ messages in thread* Re: raid40?
2011-04-16 1:10 raid40? Fyodor Ustinov
@ 2011-04-16 1:13 ` Gregory Farnum
0 siblings, 0 replies; 2+ messages in thread
From: Gregory Farnum @ 2011-04-16 1:13 UTC (permalink / raw)
To: Fyodor Ustinov; +Cc: ceph-devel
On Fri, Apr 15, 2011 at 6:10 PM, Fyodor Ustinov <ufm@ufm.su> wrote:
> Hi.
>
> Looking the sources I noticed that the "rule" in CRUSH may be type "raid4".
>
> Because of this, I have a question: Is it possible to organize the 20 OSD
> servers in the scheme 4 * (4+1)? I.e. like a stripe from 4 of raid4 sets?
>
> Plain "replication level = 2" is too expensive by "used space".
>
> WBR,
> Fyodor.
Unfortunately, no. CRUSH and some of the other auxiliary bits can do
the mappings required to support RAID, but none of the core code
required to do that is implemented. It's in mind as something that
would be nice to have in the future, but is much more complicated than
simple replication schemes.
-Greg
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