And as to min_size choice -- since you've replied exactly to that part
of mine message only.
On Sat, 13 Apr 2019 at 06:54, Paul Emmerich <paul.emmerich@xxxxxxxx> wrote:
> On Fri, Apr 12, 2019 at 9:30 PM Igor Podlesny <ceph-user@xxxxxxxx> wrote:
> > For e. g., an EC pool with default profile (2, 1) has bogus "sizing"
> > params (size=3, min_size=3).
{{
> > Min. size 3 is wrong as far as I know and it's been fixed in fresh
> > releases (but not in Luminous).
}}
I didn't give any proof when writing this due being more focused on EC
Pool usage calculation.
Take a look at:
https://github.com/ceph/ceph/pull/8008
As it can be seen formula for min_size became min_size = k + min(1, m
- 1) effectively on March 2019.
-- That's why I've said "fixed in fresh releases but not in Luminous".
Let's see what does this new formula produce for k=2, m=1 (the default
and documented EC profile):
min_size = 2 + min(1, 1 - 1) = 2 + 0 = 2.
Before that change it would be 3 instead, thus giving that 3/3 for EC (2, 1).
[...]
> min_size 3 is the default for that pool, yes. That means your data
> will be unavailable if any OSD is offline.
> Reducing min_size to 2 means you are accepting writes when you cannot
> guarantee durability which will cause problems in the long run.
> See older discussions about min_size here
Would be glad doing so, but It's not a forum (here), but mail list
instead, right(?) -- so the only way
to "see here" is to rely on search engine that might have indexed mail
list archive. If you have
specific URL or at least exact keywords allowing to find what you're
referring to, I'd gladly see
what you're talking about.
And of course I did search before writing and the fact I wrote it
anyways means I didn't find
anything answering my question "here or there".
--
End of message. Next message?
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