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

Dan Barker dbarker at visioncomm.net
Fri Aug 5 17:37:12 CEST 2011


We've been off-list for a few messages, but this is now interesting enough
to be public. I apologize for the top-posting. Please read backwards. Dan

 

Well, to be certain, I'd dd the disks to zeros individually, and then start
with them sync'd. 

 

drbdadm down all

dd if=/dev/zero of=/drbdbackingdevice bs=1M oflag=direct

 

on both sides.

 

New Blank Disk:

===============

#On both nodes, initialize meta data and configure the device.

drbdadm -- --force create-md r0

 

#They need to do the initial handshake, so they know their sizes.

drbdadm up r0

 

#They are now Connected Secondary/Secondary Inconsistent/Inconsistent.
Generate a new current-uuid and clear the dirty bitmap.

drbdadm -- --clear-bitmap new-current-uuid r0

 

#They are now Connected Secondary/Secondary UpToDate/UpToDate.

drbdadm primary r0

 

Now, recreate your empty ext3 file system and you are in sync.

 

Dan

 

From: Matt Baer [mailto:mbaer at lrnet1.com] 
Sent: Friday, August 05, 2011 11:26 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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