[DRBD-user] DRBD won't take 1G syncer rate

Roof, Morey R. MRoof at admin.nmt.edu
Fri Aug 5 17:33:09 CEST 2011

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


I would suggest looking at the disk hardware.  What sort of RAID card
are you using in the servers?  If you are using an HP Smart Array there
is some tuning to do to get some descent performance out of those as
they have a rather deep buffer.

 

-Morey

 

________________________________

From: drbd-user-bounces at lists.linbit.com
[mailto:drbd-user-bounces at lists.linbit.com] On Behalf Of Matt Baer
Sent: Friday, August 05, 2011 9:26 AM
To: Dan Barker
Cc: drbd-user at lists.linbit.com
Subject: Re: [DRBD-user] DRBD won't take 1G syncer rate

 

Well we're the perfect supplements for each other because, as you can
see, I don't know DRBD from a hole in the wall.

Yes, it's a brand new resource.  I don't think I would say it's full of
zeros, as it has a clean ext3 file system on it.

Yes, I would LOVE to skip the sync, I've been dealing with this for
weeks now and right when I was about to go live, I tested the failover
and it didn't work because of a service heartbeat wanted to start wasn't
going all that well.  While troubleshooting, I lost my 100% perfectly
live server and have to start from scratch.  Problem is I only have two
days to do it and the thing has to sync 1.8TB at 12MB/s.  I have no idea
where the bottleneck could be.  Two servers, a cable connecting eth1 to
eth1, both are auto-negotiated at 1gbps on their own /30 subnet.  The
only thing there would be garbage NIC cards, possible, but not probable,
or the cable, more likely, but I've never had an issue with it until
now.  Freshly constructed servers, too.

I tried the drbdsetup /dev/drbd0 syncer -r 120M, been running like that
for about 5 minutes now and it hasn't changed at all.



On Fri, Aug 5, 2011 at 10:13 AM, Dan Barker <dbarker at visioncomm.net>
wrote:

Is this a brand new resource? Why are you doing a full sync? If it's
brand new (full of zeros), you can skip the sync. Instructions upon
request.

 

Btw, I don't know why you are getting 12% of your requested syncer rate.
I'm not a hot-shot linux performace analyzer, but there is a bottleneck
somewhere. I get 25M routinely here on GB nics. I have my Syncer set to
25M. It drops to about 14M (each) if 2 are syncing.

 

To change sync rate without stop/start drbd: drbdsetup /dev/drbd1 syncer
-r 120M

 

AL Extents seems a bit low. I use 1801 (big prime number that felt about
right).

 

Dan

 

 

 

 

From: Matt Baer [mailto:mbaer at lrnet1.com] 
Sent: Friday, August 05, 2011 11:03 AM
To: Dan Barker


Subject: Re: [DRBD-user] DRBD won't take 1G syncer rate

 

Ok, revised /etc/drbd.conf and restarted DRBD with the following

common { syncer { rate 100M; al-extents 257; } }


And I'm getting from /proc/drbd:

GIT-hash: 3e69822d3bb4920a8c1bfdf7d647169eba7d2eb4 build by
buildsvn at c5-x8664-build, 2008-10-03 11:30:17
 0: cs:SyncTarget st:Secondary/Primary ds:Inconsistent/UpToDate C r---
    ns:0 nr:281056 dw:272864 dr:0 al:0 bm:16 lo:257 pe:1969 ua:256 ap:0
oos:1308428488
        [>....................] sync'ed:  0.1% (1277762/1278028)M
        finish: 25:57:39 speed: 13,904 (12,400) K/sec

And I only have one resource, r0.  All it's syncing right now is the
post mkfs.ext3 /dev/drbd0



On Fri, Aug 5, 2011 at 9:51 AM, Dan Barker <dbarker at visioncomm.net>
wrote:

You are still mixing megabits and megabytes. Your 1000 megabit pipe
won't take a 600 megabyte stream, or a 150 megabyte stream. The maximum
is about 125 MBps.

 

DRBD talks (and is documented to talk) bytes. Most everyone else talks
bits.

 

You don't mention the speed you are getting.

 

Also, if you have 3 resources syncing, each will try for the syncer
limit. So, to use 50% of your capacity to sync 3 resources, you'd
specify the rate as 21M. Note: you can change the rate on the fly,
during a sync.

 

Dan 

 

From: drbd-user-bounces at lists.linbit.com
[mailto:drbd-user-bounces at lists.linbit.com] On Behalf Of Matt Baer
Sent: Friday, August 05, 2011 8:51 AM
To: Caspar Smit
Cc: drbd-user at lists.linbit.com
Subject: Re: [DRBD-user] DRBD won't take 1G syncer rate

 

I was playing with the settings yesterday and it let me set it at 600M
and it didn't make a difference in the sync speed at all.  I then tried
it with your suggestion, dropped it to 150M just to be safe.  Still no
difference.  I wonder what the deal is.  Could it be that this is the
initial sync?

 

On Aug 5, 2011 1:29 AM, "Caspar Smit" <c.smit at truebit.nl> wrote:
> Hi Matt,
> 
> 1000M means 1000 Mb/s NOT 1000mbps. To reach 1000M you should have at
least
> one (probably two) 10gbit interface(s). Since you have two 1gbit
interfaces
> (bonded with balance-rr?) a value between 100M and around 170M would
be more
> appropiate.
> 
> Kind regards,
> Caspar
> Op 5 aug. 2011 08:21 schreef "Matt Baer" <mbaer at lrnet1.com> het
volgende:
>> When setting the syncer rate in drbd.conf to 1G, it won't start,
citing
> that
>> 1G is invalid. Get the same thing with 1000M. Any clue as to why? It
>> explicitly states that <mbaer at lrnet1.com>1G is acceptable in the
docs.
> I've
>> triple checked and both interfaces are auto-negotiated at 1000mbps
full
>> duplex.


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-- 
Thanks,
Matt Baer
Network Manager
Leaf River Telephone Company
102 W Second Street
Leaf River, IL 
815.738.2211 - Main Office
866.738.2211 - Toll Free
mbaer at lrnet1.com




-- 
Thanks,
Matt Baer
Network Manager
Leaf River Telephone Company
102 W Second Street
Leaf River, IL 
815.738.2211 - Main Office
866.738.2211 - Toll Free
mbaer at lrnet1.com

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