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The first step is to create an Apple Disk Image File (DMG) distribution in a GUI tool, I used DMG Packager.
Then create a directory that will contain all the files that you want included in the DMG file. The best way to do this is to mount the DMG file you created and copy the files into this directory. Then move the .app file created by BitRock into this directory.
Then run the hdiutil utility to create a DMG file
$hdiutil create /tmp/tmp.dmg -ov -volname "RecitalInstall" -fs HFS+ -srcfolder "/tmp/macosxdist/" 
Finally call hdutil to convert the writable, to a compressed (and such not writable) DMG
$hdiutil convert /tmp/tmp.dmg -format UDZO -o RecitalInstall.dmg
So now each time before you build a new distribution with the above commands, just move the new .app file into the directory containing the files to be added to the DMG file.
I've already added this to the makefile so after BitRock creates the .app file the hdiutil command is called to automatically generate the new DMG file.
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Recital is a rich and versatile product with many ways to do the same thing. Developers usually write code in the way that they are accustomed to without paying much attention to how this will perform in a multi-user environment with large amounts of users and transactions. The best way to optimize Recital applications is to use the built-in tuning capabilities introduced in Recital 10.

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If when your attempt to create device meta-data fails this is drbd preventing you from corrupting a file system present on the target partition.

$ drbdadm create-md drbd0

v08 Magic number not found
md_offset 30005817344
al_offset 30005784576
bm_offset 30004867072

Found ext2 filesystem which uses 190804004 kB
current configuration leaves usable 29301628 kB

Device size would be truncated, which
would corrupt data and result in
'access beyond end of device' errors.
You need to either
* use external meta data (recommended)
* shrink that filesystem first
* zero out the device (destroy the filesystem)
Operation refused.

Command 'drbdmeta /dev/drbd0 v08 /dev/sda4 internal create-md' terminated with exit code 40
drbdadm aborting

Once you have confirmed that the file system present on the target partition is no longer required at the prompt type the following:

Replace /dev/sdaX with the block device you are targeting.

dd if=/dev/zero of=/dev/sdaX bs=1M count=128

Once this has completed the drbdadm create-md drbd0 command will complete with a "success."

$ drbdadm create-md drbd0
v08 Magic number not found
v07 Magic number not found
v07 Magic number not found
v08 Magic number not found
Writing meta data...
initialising activity log
NOT initialized bitmap
New drbd meta data block successfully created.
success
$

 

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TIP
The Compatibility Dialog settings are written to the compat.db file in <path>/conf - please ensure that the user setting the compatibility settings has write access to this file and directory.  Once these settings are written, the dialog will not be displayed unless SET COMPATIBLE is issued.

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lslk lists information about locks held on files with local inodes on systems running linux.

Install it with:

yum install lslk
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Mac OS X leopard supports Universal Binaries so executables and dynamic libraries can be run on multiple architectures. A good example of this is the default apache install on Mac OS X. 
In order to compile apache modules for this architecture you must use the following flags when configuring the apache install.
 ./configure CFLAGS='-arch x86_64' APXSLDFLAGS='-arch x86_64' --with-apxs=/usr/sbin/apxs
Then you must pass the these additional flags to the apxs command in order to generate a Universal Binary shared module.
-Wl,-dynamic -Wl,'-arch ppc' -Wl,'-arch ppc64' -Wl,'-arch i386' -Wl,'-arch x86_64' 
-Wc,-dynamic -Wc,'-arch ppc' -Wc,'-arch ppc64' -Wc,'-arch i386' -Wc,'-arch x86_64' 
If you then do a file command on the shared module it should return; 
$ file mod_recital.so 
mod_recital2.2.so: Mach-O universal binary with 4 architectures 
mod_recital2.2.so (for architecture ppc7400): Mach-O bundle ppc 
mod_recital2.2.so (for architecture ppc64): Mach-O 64-bit bundle ppc64 
mod_recital2.2.so (for architecture i386): Mach-O bundle i386 
mod_recital2.2.so (for architecture x86_64): Mach-O 64-bit bundle x86_64
The apache module files are stored in the /usr/libexec/apache2/ directory on a default apache install on the Mac and the configuration file is /private/etc/apache2/httpd.conf
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It would appear that gigabit LAN is not! In fact it often runs at the same speed as 100Mbps LAN. Let's look at why exactly.

After configuring your network you can use the ifconfig command to see what speeds the LAN is connected. Even though 1000Mbps is reported by the card, the reality is that the overall throughtput may well be ~100Mpbs. You can try copying a large file using scp to demonstrate this.

As it turns out, in order to use a gigabit LAN you need to use CAT6 cables. CAT5 and CAT5E are not good enough. End result, the ethernet cards throttle back the speed to reduce dropped packets and errors.

You can find a good article here titled Squeeze Your Gigabit NIC for Top Performance. After tuning up the TCP parameters i found that it made no dfifference. The principal reasons behind low gigabit ethernet performance can be summed up as follows.

  1. Need to use CAT6 cables
  2. Slow Disk speed
  3. Limitations of the PCI bus which the gigabit ethernet cards use

You can get an idea about the disk speed using the hdparm command:

Display the disk partitions and choose the main linux partition which has the / filesystem.

# fdisk -l


Then get disk cache and disk read statistics:

# hdparm -Tt /dev/sda0


On my desktop system the sata disk perfomance is a limiting factor. These were the results:

/dev/sda1:
Timing cached reads:   9984 MB in  2.00 seconds = 4996.41 MB/sec
Timing buffered disk reads:   84 MB in  3.13 seconds =  58.49 MB/sec

Well, that equates to a raw disk read speed of 58.49 * 8 = 467Mbps which is half the speed of a gigabit LAN.

So.. NAS storage with lots of memory looks to be the way to go... If you use the right cables!


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All temporary files created by Recital are stored in the directory specified by the environment variable DB_TMPDIR.

 
In order to have these files stored in memory first create a temporary directory
mkdir /opt/recital/tmp
 
Then mount the directory with the tmpfs command
mount -t tmpfs -o size=1g recitaltmpfs /usr/recital/tmp
 
Then change the DB_TMPDIR variable in the recital.conf to point to the newly created temporary directory.
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In this article Barry Mavin explains step by step how to setup a Linux HA (High Availability) cluster for the running of Recital applications on Redhat/Centos 5.3 although the general configuration should work for other linux versions with a few minor changes.

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When debugging C code it is common to write debugging to an external text file using the __FILE__ and __LINE__ preprocessor defines to trace execution flow.

Unfortunately java does not support __FILE__ and __LINE__ but you can get the same functionality with this code which can be placed in one of your libraries.
	
public static void showTrace(String msg)
{
	if (msg.length() > 0) System.out.println(msg);
	System.out.println("Trace: " + 
				   "file " + new Throwable().getStackTrace()[1].getFileName() +
				   " class " + new Throwable().getStackTrace()[1].getClassName() +
				   " method " + new Throwable().getStackTrace()[1].getMethodName() +
				   " line " + new Throwable().getStackTrace()[1].getLineNumber());
}
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