Re: Squeezing Performance of CEPH

[Massimiliano Cuttini <max@xxxxxxxxxxxxx>]

Of course yes!

SSD bottleneck is the SATA controller.
If you use a NVMe/PCIe controller you get from almost the same SSD 2.400MB/sec instead of 580MB/sec.

2400MB/sec x 8 =  ~19Gbit/sec
580MB/sec x 8 = ~5 Gbit/sec

If you don't trust me take a look at this benchmark between 2 really common SSD in the consumer market:
http://ssd.userbenchmark.com/Compare/Samsung-960-Pro-NVMe-PCIe-M2-512GB-vs-Samsung-850-Pro-256GB/m182182vs2385

So of course, talking about SSD, your speed is grossy the SATA controller (minus the overhead of the protocol).

Il 22/06/2017 20:35, ceph@xxxxxxxxxxxxxx ha scritto:

On 22/06/2017 19:19, Massimiliano Cuttini wrote:

We are already expecting the following bottlenecks:

 * [ SATA speed x n° disks ] = 24Gbit/s
 * [ Networks speed x n° bonded cards ] = 200Gbit/s

6Gbps SATA does not mean you can read 6Gbps from that device

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