[DRBD-user] Performance Problem with Informix Database Server

[Lars Ellenberg]

Sorry. due to limited time I am not available as private helpdesk.
I probably need to reduce my participation on drbd-user, too.
Maybe I even need to unsubscribe here, to not be tempted...

If you need professional help, you can always ask for drbd-support at
linbit (where you then will reach me and Philipp, as well as other
experienced drbd people).

Anyways, for now I just forward this to drbd-user,
so maybe someone can pick it up.

	Lars Ellenberg


----- Forwarded message from Thomas Dingermann <td at trobisch.de> -----

Message-ID: <41346FDF.4040704 at trobisch.de>
Date: Tue, 31 Aug 2004 14:32:31 +0200
From: Thomas Dingermann <td at trobisch.de>
User-Agent: Mozilla/5.0 (X11; U; Linux i686; de-AT; rv:1.8a2) Gecko/20040714
To: Lars Ellenberg <Lars.Ellenberg at linbit.com>
Subject: Re: [DRBD-user] Performance Problem with Informix Database Server

Lars Ellenberg wrote:

>/ 2004-07-23 10:54:18 +0200
>\ Thomas Dingermann:
> 
>
>>I am using drbd-0.7 with ext3-Filesystem (data=journal). Samba, NFS and 
>>Sybase SQL-Anywhere are running fine and fast. There are no lost 
>>(commited) Transactions of Sybase SQL when resetting the primary node.
>>
>>I have a performance problem with DRBD and Informix Dynamic Server 9.40.
>>
>>Informix Server opens its database files with O_SYNC in case of normal 
>>files, so writes a very slow. Is it possible to use /dev/nbX as 
>>RAW-Device? Then Informix will open without O_SYNC.
>>   
>>
Is it possible to use /dev/nb0 as a raw device?

>
>of course, if every submitted bio is waited for first, then the
>increased latency will hit performance very hard...
>
>but are you sure it is DRBD?
>I mean what do the figures look like
>without drbd,
>with unconnected drbd,
>and with connected drbd?
> 
>
local file usage isas expected (50 MB/sec) dd if=/dev/zero of=/tmp/x 
bs=2048 count=1000000

Protocol      drbd connected      Rate(blocks/sec from vmstat)
C                     yes                           200 - 300
C                     no                             3500
B                     yes                            70 - 230
B                     no                              3500
A                     yes                           3200
A                     no                              3500

-                        -                               15000      
(test-prog on local filesstem, see below)


Network: Crossovercable with Gigabit-Ethernet
Machine A (with Databases working) Athlon64 3200+
Machine B (Secondary) Athlon XP 2800+
Harddisk: 120GB IDE


Test Network-Performance:

Machine A: nc -l  -p 49999
Machine B: dd if=/dev/zero bs=2048 count=1000000 | nc machinea 49999
2048000000 bytes transferred in 40,572747 seconds (50477233 bytes/sec)

are 50Mbytes/sec normal between Gigabit-NICs (just one Patchcable)?

Ping-Time: 0.05 ms

Test-Prog is doing the same as INFORMIX-DYNAMIC-SERVER (Block-size 2048 
Bytes)

 if ( ( fd = open( "x", O_WRONLY | O_SYNC ) ) == -1 )
...
 for ( i = 0; i < 100000; i++ )
...
     if ( write( fd, ptr_pc, 2048 ) < 0 )
...

What do think about using Informix with drbd?

Best regards,

Thomas

----- End forwarded message -----