Am 22.11.2012 16:26, schrieb Alexandre DERUMIER:
Haven't tested that. But does this makes sense? I mean data goes to Disk
journal - same disk then has to copy the Data from part A to part B.
Why is this an advantage?
Well, if you are cpu limited, I don't think you can use all 8*35000iops by node.
So, maybe a benchmark can tell us if the difference is really big.
Using tmpfs and ups can be ok, but if you have a kernel panic or hardware
problem, you'll lost your journal.
But who cares? it's also on the 2nd node. or even on the 3rd if you have
replicas 3.
Stefan
----- Mail original -----
De: "Stefan Priebe - Profihost AG" <s.pri...@profihost.ag>
À: "Mark Nelson" <mark.nel...@inktank.com>
Cc: "Alexandre DERUMIER" <aderum...@odiso.com>, "ceph-devel" <ceph-devel@vger.kernel.org>, "Mark
Kampe" <mark.ka...@inktank.com>, "Sébastien Han" <han.sebast...@gmail.com>
Envoyé: Jeudi 22 Novembre 2012 16:01:56
Objet: Re: RBD fio Performance concerns
Am 22.11.2012 15:46, schrieb Mark Nelson:
I haven't played a whole lot with SSD only OSDs yet (other than noting
last summer that iop performance wasn't as high as I wanted it). Is a
second partition on the SSD for the journal not an option for you?
Haven't tested that. But does this makes sense? I mean data goes to Disk
journal - same disk then has to copy the Data from part A to part B.
Why is this an advantage?
Stefan
Mark
On 11/22/2012 08:42 AM, Stefan Priebe - Profihost AG wrote:
Am 22.11.2012 15:37, schrieb Mark Nelson:
I don't think we recommend tmpfs at all for anything other than playing
around. :)
I discussed this with somebody frmo inktank. Had to search the
mailinglist. It might be OK if you're working with enough replicas and
UPS.
I see no other option while working with SSDs - the only Option would be
to be able to deaktivate the journal at all. But ceph does not support
this.
Stefan
On 11/22/2012 08:22 AM, Stefan Priebe - Profihost AG wrote:
Hi,
can someone from inktank comment this? Might be using /dev/ram0 with an
fs on it be better than tmpfs as we can use dio?
Greets,
Stefan
----- Mail original -----
De: "Stefan Priebe - Profihost AG" <s.pri...@profihost.ag>
À: "Sébastien Han" <han.sebast...@gmail.com>
Cc: "Mark Nelson" <mark.nel...@inktank.com>, "Alexandre DERUMIER"
<aderum...@odiso.com>, "ceph-devel" <ceph-devel@vger.kernel.org>,
"Mark Kampe" <mark.ka...@inktank.com>
Envoyé: Jeudi 22 Novembre 2012 14:29:03
Objet: Re: RBD fio Performance concerns
Am 22.11.2012 14:22, schrieb Sébastien Han:
And RAMDISK devices are too expensive.
It would make sense in your infra, but yes they are really expensive.
We need something like tmpfs - running in local memory but support
dio.
Stefan
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