[DRBD-user] DRBD keeps doing full resync

[Cesar Peschiera]

>  net {
>    data-integrity-alg crc32c; # crc32c, sha1, md5
>  }
This option only must be used for purposes of test, and never in a
production environment.
This directive commonly break the link of replication and produce into DRBD
a disconnection and, obviously, also a  "OOS" (out of sync)

>  syncer {
>    csums-alg crc32c; # crc32c, sha1, md5
>  }
I guess that is better to use "sha1", due to that is more robust.

And finally, is highly advisable to use the latest stable versions:
- drbd-utils 8.9.3 version
- drbd-8.4.6 or drbd-9.0.0 version (depending of your intentions in the 
amount of DRBD replicated volumes)

Three tips of Hardware (common mistakes of many people):
1- Never uses NICs of the Realtek brand, at least for me, DRBD didn't work
well with this brand.
(but neither i did a test with the latest driver version.... ??? )

2- Moreover, if you have Servers with Intel processors, and your NICs
supports I/OAT DMA Engine, will be better to have it enabled in the Bios of
the server, with it enabled, the NICs will have access direct to the memory
of the Server (and obviously, it will gain speed), as also it will have less
consume of processor cycles.

3- Always is advisable update all the firmwares of each element of Hardware
that has your Servers (NICs, Bios, Chipsets, IDRAC, RAID controllers, etc.)



----- Original Message ----- 
From: "Helmut Wollmersdorfer" <helmut.wollmersdorfer at fixpunkt.de>
To: <drbd-user at lists.linbit.com>
Cc: <drbd-user at lists.linbit.com>
Sent: Thursday, August 20, 2015 3:14 AM
Subject: Re: [DRBD-user] DRBD keeps doing full resync


>
>
> Am 19.08.2015 um 06:35 schrieb Viktor Villafuerte
> <viktor.villafuerte at optusnet.com.au>:
>
>> Would you have any possible explanation for this? I did read man pages
>> and about timeouts etc but I wonder why sometimes when the connection,
>> after the sync, is broken it does full sync and this time it did only
>> partial sync? The connection was broken just the same (according to
>> logs).
>
> Maybe network hiccups. I had some unexplainable problems during migrating
> drbd-devices to other clusters using the service IPs. Sometimes it worked,
> sometimes not.
>
> After using
>
>  net {
>    data-integrity-alg crc32c; # crc32c, sha1, md5
>  }
>  syncer {
>    csums-alg crc32c; # crc32c, sha1, md5
>  }
>
> in the configuration this sort of problems was away.
>
> HTH
>
> Helmut Wollmersdorfer
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