Re: [ceph-users] why was osd pool default size changed from 2 to 3.

2015-10-26 Thread Lincoln Bryant
>but because there were only two copies it had no way to tell which one was >correct, and when I forced it to choose it often chose wrong. Yeah. This is a BIG problem with only running with two copies. Good luck if your pgs ever get inconsistent :) --Lincoln > On Oct 26, 2015, at 10:41 AM,

Re: [ceph-users] why was osd pool default size changed from 2 to 3.

2015-10-26 Thread Quentin Hartman
TL;DR - Running two copies in my cluster cost me a weekend, and many more hours of productive time during normal working hours. Networking problems can be just as destructive as disk problems. I only run 2 copies on throwaway data. So, I have personal experience in data loss when running only two

Re: [ceph-users] why was osd pool default size changed from 2 to 3.

2015-10-24 Thread Christian Balzer
Hello, There have been COUNTLESS discussions about Ceph reliability, fault tolerance and so forth in this very ML. Google is very much evil, but in this case it is your friend. In those threads you will find several reliability calculators, some more flawed than others, but penultimately you

Re: [ceph-users] why was osd pool default size changed from 2 to 3.

2015-10-24 Thread Stefan Eriksson
> Am 23.10.2015 um 20:53 schrieb Gregory Farnum: >> On Fri, Oct 23, 2015 at 8:17 AM, Stefan Eriksson wrote: >> >> Nothing changed to make two copies less secure. 3 copies is just so >> much more secure and is the number that all the companies providing >> support recommend, so

Re: [ceph-users] why was osd pool default size changed from 2 to 3.

2015-10-24 Thread Wido den Hollander
On 10/24/2015 09:41 AM, Stefan Eriksson wrote: >> Am 23.10.2015 um 20:53 schrieb Gregory Farnum: >>> On Fri, Oct 23, 2015 at 8:17 AM, Stefan Eriksson > wrote: >>> >>> Nothing changed to make two copies less secure. 3 copies is just so >>> much more secure and is the number

[ceph-users] why was osd pool default size changed from 2 to 3.

2015-10-23 Thread Stefan Eriksson
Hi I have been looking for info about "osd pool default size" and the reason its 3 as default. I see it got changed in v0.82 from 2 to 3, Here its 2. http://docs.ceph.com/docs/v0.81/rados/configuration/pool-pg-config-ref/ and in v0.82 its 3.

Re: [ceph-users] why was osd pool default size changed from 2 to 3.

2015-10-23 Thread Corin Langosch
Am 23.10.2015 um 20:53 schrieb Gregory Farnum: > On Fri, Oct 23, 2015 at 8:17 AM, Stefan Eriksson wrote: > > Nothing changed to make two copies less secure. 3 copies is just so > much more secure and is the number that all the companies providing > support recommend, so we

Re: [ceph-users] why was osd pool default size changed from 2 to 3.

2015-10-23 Thread Gregory Farnum
On Fri, Oct 23, 2015 at 8:17 AM, Stefan Eriksson wrote: > Hi > > I have been looking for info about "osd pool default size" and the reason > its 3 as default. > > I see it got changed in v0.82 from 2 to 3, > > Here its 2. >