Re: SSD recommendations for OSD journals

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Hi,

On Mon, Jul 22, 2013 at 2:08 AM, Chen, Xiaoxi <xiaoxi.chen@xxxxxxxxx> wrote:

Hi,

 

         > Can you share any information on the SSD you are using, is it PCIe connected?

       Depends, if you use HDD as your OSD data disk,  a SATA/SAS SSD is enough for you. Instead of Intel 520, I would like to suggest you use the Intel DCS3700 since it provide better durability for write. Since a DCS3700 can provide 400~500MB/s for write and HDD can only have ~100MB/s ,it’s safe for a DCS3700 to provide journal for 4~5 HDDs.

Indeed, I am using 2TB SATA 7200 drives in the OSDs, but unable to make room for the SSD, not even for a 2.5" drive.
Considering using a mSATA to PCIe adapter with a SATA III mSATA SSD. Any thoughts on what to expect from this combination?

        And , if you have some insight/assumption on your workload, say “ I don’t care throughtput at all , all my workload doing random access”. With such assumption , you can have very high SSD:HDD ratio, 8:1 or even 10:1 will also be fine

My workload will be read and write heavy, mostly random I/O (mail servers, OpenStack VMs, multi-node video recording and streaming), I'm afraid this will kill smaller SSDs too quickly to be sustainable, not so?


Charles
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