[DRBD-user] drbd storage size

Meij, Henk hmeij at wesleyan.edu
Fri Oct 24 16:12:41 CEST 2014

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

a) raise that limit temporarily with commandline calls (see the docs)

if you could point me to the sub command that would be great - this is about the initial first sync

I have set sync rate in my config (none, 100M, 300M, 800M) nothing changes. I have also read about the c-max-rate and c-fill-target but they all have to do with resync and nothing changes re first sync


From: drbd-user-bounces at lists.linbit.com [drbd-user-bounces at lists.linbit.com] on behalf of Arnold Krille [arnold at arnoldarts.de]
Sent: Thursday, October 23, 2014 5:34 PM
To: drbd-user at lists.linbit.com
Subject: Re: [DRBD-user] drbd storage size

On Thu, 23 Oct 2014 20:10:31 +0000 "Meij, Henk" <hmeij at wesleyan.edu>
> a) it turns out the counter  (8847740/11287100)M goes down, not up,
> deh, never noticed
> b) ran plain  rsync across eth0 (public, with switches/routers) and
> eth1 (nic to nic) eth0 sent 585260755954 bytes  received 10367 bytes
> 116690412.98 bytes/sec eth1 sent 585260755954 bytes  received 10367
> bytes  122580535.41 bytes/sec so my LSI raid card is behaving and
> DRBD is slowing the initialization down somehow. Found chapter 15 and
> will try some suggestions but ideas welcome.
> c) for grins
> version: 8.4.5 (api:1/proto:86-101)
> GIT-hash: 1d360bde0e095d495786eaeb2a1ac76888e4db96 build by
> mockbuild at Build64R6, 2014-08-17 19:26:04 0: cs:SyncTarget
> ro:Secondary/Secondary ds:Inconsistent/UpToDate C r----- ns:0
> nr:3601728 dw:3601408 dr:0 al:0 bm:0 lo:4 pe:11 ua:3 ap:0 ep:1 wo:f
> oos:109374215324 [>....................] sync'ed:  0.1%
> (106810756/106814272)M finish: 731:23:05 speed: 41,532 (31,868) want:
> 41,000 K/sec
> 100TB in 731 hours would  be 30 days. Can I expect large delta data
> replication to go equally slow using DRDB?

Your drbd is set to _want_ only ~40MB/s for sync. You can:
a) raise that limit temporarily with commandline calls (see the docs)
b) raise that limit permanently in the config files (see the docs too)
c) expect the normal replication to be faster then that (provided your
network is faster) as normal replication works as fast as the
connection allows.

The sync is usually limited in transfer-rates so it doesn't eat all the
bandwidth and leaves nothing for the already running resources (or the
running of the syncing resource).

- Arnold

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