Cc: Alexander E. Patrakov; Mario Giammarco; ceph-users
Subject: Re: [ceph-users] Re: Worst thing that can happen if I have size= 2
How do you achieve that? 2 hours? Install new drive for db is 10min of DC
engineer hand work (if drive is HHHL and need power off server). Then after
server is boots your
egards,
=
Frank Schilder
AIT Risø Campus
Bygning 109, rum S14
From: Mario Giammarco
Sent: 05 February 2021 21:10:33
To: Eneko Lacunza
Cc: Ceph Users
Subject: [ceph-users] Re: Worst thing that can happen if I have size= 2
Il giorno gio 4 feb 202
avalon.org.ua
> Cc: "ceph-users"
> Sent: Wednesday, February 3, 2021 4:43:08 AM
> Subject: [ceph-users] Re: Worst thing that can happen if I have size= 2
>
> On Wed, 2021-02-03 at 09:39 +, Max Krasilnikov wrote:
> > > if a OSD becomes unavailble (broken disk, rebo
On 05/02/2021 20:10, Mario Giammarco wrote:
It is not that a morning I wake up and put some random hardware together,
I followed guidelines.
The result should be:
- if a disk (or more) brokes work goes on
- if a server brokes the VMs on the server start on another server and
work goes on.
The
Il giorno gio 4 feb 2021 alle ore 12:19 Eneko Lacunza
ha scritto:
> Hi all,
>
> El 4/2/21 a las 11:56, Frank Schilder escribió:
> >> - three servers
> >> - three monitors
> >> - 6 osd (two per server)
> >> - size=3 and min_size=2
> > This is a set-up that I would not run at all. The first one
alert at night, I want to be able to turn around
and continue sleeping.
Best regards,
=
Frank Schilder
AIT Risø Campus
Bygning 109, rum S14
From: Alexander E. Patrakov
Sent: 04 February 2021 11:35:27
To: Mario Giammarco
Cc: ceph-users
Subje
volume lvm create --osd-id 1234
Cheers, Dan
>
> thanks a lot,
>
> Samuel
>
>
>
>
> huxia...@horebdata.cn
>
>
> From: Dan van der Ster
> Date: 2021-02-04 11:57
> To: Mario Giammarco
> CC: Ceph Users
> Subject: [ceph-u
From: Dan van der Ster
Date: 2021-02-04 11:57
To: Mario Giammarco
CC: Ceph Users
Subject: [ceph-users] Re: Worst thing that can happen if I have size= 2
On Thu, Feb 4, 2021 at 11:30 AM Mario Giammarco wrote:
>
>
>
> Il giorno mer 3 feb 2021 alle ore 21:22 Dan van der Ster
> h
>
> Maybe the weakest thing in that configuration is having 2 OSDs per node; osd
> nearfull must be tuned accordingly so that no OSD goes beyond about 0.45, so
> that in case of failure of one disk, the other OSD in the node has enough
> space for healing replication.
>
A careful setting
Hi all,
El 4/2/21 a las 11:56, Frank Schilder escribió:
- three servers
- three monitors
- 6 osd (two per server)
- size=3 and min_size=2
This is a set-up that I would not run at all. The first one is, that ceph lives
on the law of large numbers and 6 is a small number. Hence, your OSD
n van der Ster
Sent: 04 February 2021 11:57:38
To: Mario Giammarco
Cc: Ceph Users
Subject: [ceph-users] Re: Worst thing that can happen if I have size= 2
On Thu, Feb 4, 2021 at 11:30 AM Mario Giammarco wrote:
>
>
>
> Il giorno mer 3 feb 2021 alle ore 21:22 Dan van der Ster
> ha
==
Frank Schilder
AIT Risø Campus
Bygning 109, rum S14
From: Mario Giammarco
Sent: 04 February 2021 11:29:49
To: Dan van der Ster
Cc: Ceph Users
Subject: [ceph-users] Re: Worst thing that can happen if I have size= 2
Il giorno mer 3 feb 2021 alle ore 21:22
Hi,
Am 04.02.21 um 12:10 schrieb Frank Schilder:
> Going to 2+2 EC will not really help
On such a small cluster you cannot even use EC because there are not
enough independent hosts. As a rule of thumb there should be k+m+1 hosts
in a cluster AFAIK.
Regards
--
Robert Sander
Heinlein Support
On Thu, Feb 4, 2021 at 11:30 AM Mario Giammarco wrote:
>
>
>
> Il giorno mer 3 feb 2021 alle ore 21:22 Dan van der Ster
> ha scritto:
>>
>>
>> Lastly, if you can't afford 3x replicas, then use 2+2 erasure coding if
>> possible.
>>
>
> I will investigate I heard that erasure coding is slow.
>
>
There is a big difference between traditional RAID1 and Ceph. Namely, with
Ceph, there are nodes where OSDs are running, and these nodes need
maintenance. You want to be able to perform maintenance even if you have
one broken OSD, that's why the recommendation is to have three copies with
Ceph.
Il giorno mer 3 feb 2021 alle ore 21:22 Dan van der Ster
ha scritto:
>
> Lastly, if you can't afford 3x replicas, then use 2+2 erasure coding if
> possible.
>
>
I will investigate I heard that erasure coding is slow.
Anyway I will write here the reason of this thread:
In my customers I have
Il giorno gio 4 feb 2021 alle ore 00:33 Simon Ironside <
sirons...@caffetine.org> ha scritto:
>
>
> On 03/02/2021 19:48, Mario Giammarco wrote:
>
> To labour Dan's point a bit further, maybe a RAID5/6 analogy is better
> than RAID1. Yes, I know we're not talking erasure coding pools here but
>
Hi Federico,
here I am not mixing raid1 with ceph. I am doing a comparison: is it safer
to have a server with raid1 disks or two servers with ceph and size=2
min_size=1 ?
We are talking about real world examples where a customer is buying a new
server and want to choose.
Il giorno gio 4 feb 2021
On 03/02/2021 19:48, Mario Giammarco wrote:
It is obvious and a bit paranoid because many servers on many customers
run on raid1 and so you are saying: yeah you have two copies of the data
but you can broke both. Consider that in ceph recovery is automatic,
with raid1 some one must manually
Ceph is multiple factors more risky with min_size 1 than good old raid1:
With raid1, having disks A and B, when disk A fails, you start recovery to
a new disk A'. If disk B fails during recovery then you have a disaster.
With Ceph, we have multiple servers and multiple disks: When an OSD fails
Thanks Simon and thanks to other people that have replied.
Sorry but I try to explain myself better.
It is evident to me that if I have two copies of data, one brokes and while
ceph creates again a new copy of the data also the disk with the second
copy brokes you lose the data.
It is obvious and
On 03/02/2021 09:24, Mario Giammarco wrote:
Hello,
Imagine this situation:
- 3 servers with ceph
- a pool with size 2 min 1
I know perfectly the size 3 and min 2 is better.
I would like to know what is the worst thing that can happen:
Hi Mario,
This thread is worth a read, it's an oldie but
ednesday, February 3, 2021 8:50 AM
To: Magnus HAGDORN
Cc: ceph-users
Subject: [ceph-users] Re: Worst thing that can happen if I have size= 2
Isn't this somewhat reliant on the OSD type?
Redhat/Micron/Samsung/Supermicro have all put out white papers backing the idea
of 2 copies on NVMe's as
NVMe's as safe for production.
>
>
> From: "Magnus HAGDORN"
> To: pse...@avalon.org.ua
> Cc: "ceph-users"
> Sent: Wednesday, February 3, 2021 4:43:08 AM
> Subject: [ceph-users] Re: Worst thing that can happen if I have size= 2
>
> On Wed, 2021-02-03 at 09:39 +
Subject: [ceph-users] Re: Worst thing that can happen if I have size= 2
Isn't this somewhat reliant on the OSD type?
Redhat/Micron/Samsung/Supermicro have all put out white papers backing the idea
of 2 copies on NVMe's as safe for production.
From: "Magnus HAGDORN"
To: pse...@ava
On Wed, 2021-02-03 at 09:39 +, Max Krasilnikov wrote:
> > if a OSD becomes unavailble (broken disk, rebooting server) then
> > all
> > I/O to the PGs stored on that OSD will block until replication
> > level of
> > 2 is reached again. So, for a highly available cluster you need a
> >
День добрий!
Wed, Feb 03, 2021 at 09:29:52AM +, Magnus.Hagdorn wrote:
> if a OSD becomes unavailble (broken disk, rebooting server) then all
> I/O to the PGs stored on that OSD will block until replication level of
> 2 is reached again. So, for a highly available cluster you need a
>
if a OSD becomes unavailble (broken disk, rebooting server) then all
I/O to the PGs stored on that OSD will block until replication level of
2 is reached again. So, for a highly available cluster you need a
replication level of 3
On Wed, 2021-02-03 at 10:24 +0100, Mario Giammarco wrote:
> Hello,
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