[DRBD-user] Poor fsync performance

Nik Martin nik.martin at nfinausa.com
Fri Jan 11 20:56:32 CET 2013



On 01/11/2013 08:10 AM, Andy Dills wrote:
> On Fri, 11 Jan 2013, Shaun Thomas wrote:
>
>> On 01/10/2013 11:49 PM, Andy Dills wrote:
>>
>>> So, it seems to me that even with the no-disk-barrier and no-disk-flushes,
>>> when I am connected, I am limited (write speed) to the speed of the
>>> network connection.
>>
>> These options are only so you're not *also* constrained by buffer flushing and
>> barrier operations. In the default protocol C, all writes must be synced on
>> both nodes before they're successful. That means your writes will be, at most,
>> the speed of your network interface.
>>
>> We use dual 10Gb NICs on all of our servers, and bond them to separate
>> switches for redundancy. I didn't want to go overboard so I gave DRBD a
>> bandwidth limit, but I can get 350MBps from each of the 2 DRBD devices I have
>> set up on our servers, and have plenty left over.
>>
>> I really wouldn't suggest running DRBD *without* a 10Gb NIC.
>
> Thank you, this is what I was starting to suspect, but hadn't seen
> explicitly stated anywhere.
>
> Any positive recommendations on 10Gb NICs?

We use Intel x520 DA2 SFP+ cards and they are excellent.
>
> Andy
>
> ---
> Andy Dills
> Xecunet, Inc.
> www.xecu.net
> 301-682-9972
> ---
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-- 

Regards,

Nik

Nik Martin
nfina Technologies, Inc.
+1.251.243.0043 x1003
http://nfinausa.com
Relentless Reliability



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