Re: help needed

[Nick Fisk <nick@xxxxxxxxxx>]

If it helps, I’m seeing about a 3GB DB usage for a 3TB OSD about 60% full. This is with a pure RBD workload, I believe this can vary depending on what your Ceph use case is.

 

From: ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx] On Behalf Of David Turner
Sent: 06 September 2018 14:09
To: Muhammad Junaid <junaid.fsd.pk@xxxxxxxxx>
Cc: ceph-users@xxxxxxxxxxxxxx
Subject: Re: help needed

 

The official ceph documentation recommendations for a db partition for a 4TB bluestore osd would be 160GB each.

 

Samsung Evo Pro is not an Enterprise class SSD. A quick search of the ML will allow which SSDs people are using.

 

As was already suggested, the better option is an HBA as opposed to a raid controller. If you are set on your controllers, write-back is fine as long as you have BBU. Otherwise you should be using write-through.

 

On Thu, Sep 6, 2018, 8:54 AM Muhammad Junaid <junaid.fsd.pk@xxxxxxxxx> wrote:

Thanks. Can you please clarify, if we use any other enterprise class SSD for journal, should we enable write-back caching available on raid controller for journal device or connect it as write through. Regards.

 

On Thu, Sep 6, 2018 at 4:50 PM Marc Roos <M.Roos@xxxxxxxxxxxxxxxxx> wrote:

 


Do not use Samsung 850 PRO for journal
Just use LSI logic HBA (eg. SAS2308)


-----Original Message-----
From: Muhammad Junaid [mailto:junaid.fsd.pk@xxxxxxxxx]
Sent: donderdag 6 september 2018 13:18
To: ceph-users@xxxxxxxxxxxxxx
Subject: help needed

Hi there

Hope, every one will be fine. I need an urgent help in ceph cluster
design. We are planning 3 OSD node cluster in the beginning. Details are
as under:

Servers: 3 * DELL R720xd
OS Drives: 2 2.5" SSD
OSD Drives: 10  3.5" SAS 7200rpm 3/4 TB
Journal Drives: 2 SSD's Samsung 850 PRO 256GB each Raid controller: PERC
H710 (512MB Cache) OSD Drives: On raid0 mode Journal Drives: JBOD Mode
Rocks db: On same Journal drives

My question is: is this setup good for a start? And critical question
is: should we enable write back caching on controller for Journal
drives? Pls suggest. Thanks in advance. Regards.

Muhammad Junaid

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