[DRBD-user] Hardware-recomendation needed

Florian Haas florian at hastexo.com
Tue Apr 3 13:17:56 CEST 2012

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

On Tue, Apr 3, 2012 at 12:28 PM, Maurits van de Lande
<M.vandeLande at vdl-fittings.com> wrote:
>>What do the experts think: Should this be sufficient to get the perfomance of a single SATA-Disk without DRBD?
> Probably not, nothing will.

Beg to differ.

The question was, will DRBD pair of SSDs, when replicated with
protocol C, match the performance of a single standalone SATA drive.
And at least in terms of throughput, you bet it will. A single SATA
drive would sustain 50-60MB/s streaming writes max, and that should
_definitely_ be doable with a protocol C replicated pair of SSDs.

And latency wise, Lars has already given his view on that which I
agree with, so I don't need to rehash.

> I'm using drbd in primary/primary mode to host KVM images on a two node cluster. (with drbd8.3.12, drbd8.4.1 has some performance issues)
> I have switched to SSD's myself(in raid 5 mode). This improved the VM performance, (I guess because reading data is much faster), but drbd syncer speed did not improve. I even installed a 10G network backbone and used 10G network adapters on the servers. But still syncer speed does not go beyond 110MB/s.

Ahem. I'm almost certain you're failing to provide some crucial piece
of information here. We have customers on 8.3 happily replicating in
excess of 300MB/s. That's on Infiniband hardware, but 10G is also
certainly capable of going faster than 110MB/s.

Just my €0.02.


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