[DRBD-user] Poor fsync performance

Shaun Thomas sthomas at optionshouse.com
Fri Jan 11 14:57:24 CET 2013

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

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.

Shaun Thomas
OptionsHouse | 141 W. Jackson Blvd. | Suite 500 | Chicago IL, 60604
sthomas at optionshouse.com


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