[DRBD-user] WinDRBD performance/features

[Johannes Thoma]

Hi Max,

Thank you for testing WinDRBD.

Am 29.01.20 um 06:02 schrieb Max Bergmann:
> Hi drbd-users,
> 
> Recently, I've been testing windrbd, but I can't seem to achieve more than 100 Mbps (~12mb/s) throughout, even thought the network between my nodes is 1Gpbs or more, with a simple UNC share between hosts I get 100mb/s.

> Drbd documentation mentions to adjusting c- parameters, but I still can't increase the performance.

Did you check the DRBD user's guide
(https://docs.linbit.com/docs/users-guide-9.0/#p-performance)?

Since WinDRBD is DRBD internally, the strategies for performance
tuning should be the same.

> 
> Surely I must be doing something wrong, here is my example config:
> 
>      protocol    C;
> 
>      net {
>          use-rle no;
>          max-buffers 8000;
>          max-epoch-size 8000;
>          sndbuf-size 0;

I am not sure if autotuning the send buffer size is working as expected
with WinDRBD. Please try to set a different value, 10MB is an example:

	sndbuf-size 10485760;
	rcvbuf-size 10485760;

Also set the rcvbuf size.

Also Robert Altnöder mentioned that experimenting with max-buffers helps in most
cases.
> 
>      }
> 
>      disk {
>          c-plan-ahead 5;
>          c-max-rate 125M;
>          c-min-rate 30M;
>          c-fill-target 2M;
>          al-extents 6007;
>          no-disk-barrier;
>          no-disk-flushes;
>      }
> 
> 
> Have you done any performance testing on WinDRBD?

Since we work with VMs we did not do 'real' performance tests, however
some users reported Windows performance numbers for the WinDRBD
devices. They are similar to storage on the local disk.

Another feature I'm missing is converting an existing NTFS volume with its data to be used by drbd?

Yes you can do this.

First do a backup of your data, in case something goes wrong.

Configure external drbd meta data (for meta data you need a separate
partition about 1/1000th the size of the data partition), and the
volume as backing device.

Then do a
	
	drbdadm create-md <res>

on that resource, then do a

	drbdadm up <res>

on the resource. Note that that step 'hides' the partition
from Windows so it cannot access it directly (see
windrbd hide-filesystem). You then can do a

	drbdadm primary --force <res>

in order to tell DRBD that the disk contains valid data.

Please let me know if the above steps work for you (maybe I forgot
something).

> Checksum support is another feature that I couldn't get working on windows, any hints?

Checksum support? You mean online-verify? Online verify is currently disabled,
it would take a few days work to enable it (I don't think it is that hard,
its just that no one requested that feature so far ...)

> Kind regards,
> Max

Best regards,

- Johannes