Apple advertisment

Very nice Apple advertisment against Microsoft ;-)

Very interesting blog about DB & STORAGE performance

Christian has a lot of practical experiences with DB & Storage performance tunning. Look at http://christianbilien.wordpress.com/ and read some articles there. I have similar practical experiences.

AJAX suite

I found very interesting AJAX suite of dynamic web components. See at Zapatec web site.

VMWare appliances with pre-installed Operating Systems

Pre-installed OS images for VMWare should speed up deployment of particular OS. You can find out some images at http://www.thoughtpolice.co.uk/vmware/

Internet FailOver script for FreeBSD written in Perl

I wrote Perl script to automatically detect internet uplink failure and switch over to backup internet link. When primary link is up again script will switch it back. Script must be run in crontab as often as you wish.

#!/usr/bin/perl
use Net::Frame::Device;
use Net::Ping;

$uplink1_interface="sis0";
$uplink2_interface="sis1";
$lan_interface="sis2";
$primary_gateway="10.0.3.1";
$secondary_gateway="10.10.1.1";

# print current date and time
($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = gmtime(time);
$year=$year+1900;
print "GMT Time: $year-$mon-$mday $hour:$min:$sec\n";

my $device_uplink1 = Net::Frame::Device->new(dev => $uplink1_interface);
my $device_uplink2 = Net::Frame::Device->new(dev => $uplink2_interface);
my $device_lan = Net::Frame::Device->new(dev => $lan_interface);

print "Current default gateway:", $device_lan->gatewayIp, "\n";
print "Primary default gateway:", $primary_gateway, "\n";
print "Secondary gateway:", $secondary_gateway, "\n";

print "Checking primary internet uplink ...\n";
if (check_uplink($primary_gateway)) {
if ($device_lan->gatewayIp ne $primary_gateway) {
# set default route to $primary_gateway
`route delete default`;
`route add default $primary_gateway`;

# Change uplink interface to uplink1_interface
change_nat_interface($uplink1_interface);

# restart IPFW and NATD daemon
`/etc/rc.d/ipfw restart`;

print "Default gateway has been changed to $primary_gateway via interface $uplink1_interface\n";
} else {
print "Current default gateway is set to primary gateway and is ok\n";
}
} elsif (check_uplink($secondary_gateway)) {
if ($device_lan->gatewayIp ne $secondary_gateway) {
# set default route to $secondary_gateway
`route delete default`;
`route add default $secondary_gateway`;

# Change uplink interface to uplink2_interface
change_nat_interface($uplink2_interface);

# restart IPFW and NATD daemon
`/etc/rc.d/ipfw restart`;

print "Default gateway has been changed to $secondary_gateway via interface $uplink2_interface\n";
} else {
print "Current default gateway is set to secondary gateway and is ok\n";
}
} else {
print "Any uplink is up and working\n";
}

print "----\n";

######################################################
# Ping IP address and decide if it's reachable or not
# 1.parameter: IP
######################################################
sub check_uplink {
my ($ip) = @_;

my $p = Net::Ping->new("icmp");
my $ok = $p->ping($ip);
$p->close();

return $ok; # 0 - false; 1 - true
}

######################################################
# Change NATD interface file
# 1.parameter: network interface
######################################################
sub change_nat_interface {
my ($nat_if) = @_;

$filename="/tmp/natd_iface";
if (open(F, "> $filename")) {
print "change_nat_iface: writing $nat_if to $filename\n";
print F $nat_if;
close F;
} else {
print "change_nat_iface: Cannot write to $filename\n";
return 0;
}

return 1; # 0 - false; 1 - true
}

VMWare Certified Professional

I have passed VMWARE VCP Exam on 12-Dec-2007. CANDIDATE ID: VCP026715

FreeBSD 6.2 and CDMA modem Eurotel Any Data

Howto setup CDMA in FreeBSD 6.2

Excelent documentation for Soekris

Soekris is extremely good hardware for embedded computing and applications.
Documentation and howto scenarios are available at Ultradesic website.
FreeBSD configuration of serial console is documented at Handbook

How to build VMWare image for VMWare Player free of charge

Very good howto is available at this link.

Here is copy of this article ...

If you haven't done so yet, download the Free VMware Player.

Next, you need the qemu-img.exe program that comes with QEMU. If you are using Windows (like I do) you can download QemuInstall-0.7.2.exe. After downloading this program, install it. Start a command prompt and go to the installation directory of QEMU, for example:

cd C:\Program Files\Qemu

and create a VMware disk file as follows:

C:\Program Files\Qemu>qemu-img.exe create -f vmdk WindowsXPPro.vmdk 2G
Formating 'WindowsXPPro.vmdk', fmt=vmdk, size=2097152 kB

A file "WindowsXPPro.vmdk" with a maximum disk size of 2G (the actual file is much smaller about 320 KB) has been created. You might want to move this file to a different folder.

Note: I have made several empty VMware virtual disk files of various sizes available as a single 21 KB download.

Now, create an empty text file, and rename it to "WindowsXPPro.vmx" (use the same name as in the previous step, but use vmx as the extension instead). Open the file in an editor and enter the following values:

config.version = "8"
virtualHW.version = "3"
ide0:0.present = "TRUE"
ide0:0.filename = "WindowsXPPro.vmdk"
memsize = "64"
MemAllowAutoScaleDown = "FALSE"
ide1:0.present = "TRUE"
ide1:0.fileName = "auto detect"
ide1:0.deviceType = "cdrom-raw"
ide1:0.autodetect = "TRUE"
floppy0.present = "FALSE"
ethernet0.present = "TRUE"
usb.present = "TRUE"
sound.present = "TRUE"
sound.virtualDev = "es1371"
displayName = "Windows XP Pro"
guestOS = "winXPPro"
nvram = "WindowsXPPro.nvram"
MemTrimRate = "-1"

ide0:0.redo = ""
ethernet0.addressType = "generated"
uuid.location = "56 4d 5c cc 3d 4a 43 29-55 89 5c 28 1e 7e 06 58"
uuid.bios = "56 4d 5c cc 3d 4a 43 29-55 89 5c 28 1e 7e 06 58"
ethernet0.generatedAddress = "00:0c:29:7e:06:58"
ethernet0.generatedAddressOffset = "0"

tools.syncTime = "TRUE"
ide1:0.startConnected = "TRUE"

uuid.action = "create"

checkpoint.vmState = ""

Insert your Windows XP Professional CD ROM, and double click on the file you just created. The VMware Player should boot the CD, and you can install Windows XP Pro.
Windows XP Pro up and running in a virtual machine
Windows XP Pro up and running in a virtual machine

Other versions of Windows
I first tried to install Windows 2000 Professional. When I got the installation process running I stopped the virtual machine, because I wanted to try XP. The value of guestOS was set to "windows2000pro" in the vmx configuration file.

Speed of disk subsystem can be business critical

INTRODUCTION
As a DELL System/Solution Consultant I designed hardware infrastructure for one Czech commercial ISP which wants to provide IPTV and VoD. ISP choosed software IPTV/VoD/DRM solution based on Linux OS. Together with software provider we choosed several servers PE 2970 which are AMD (x86_64) based servers. Streamer server needs cost-effective however fast enough disk subsystem. Unfortunatly, 2.5" hdd are available only as 10k rpm so streamer has eight 2.5" SAS 73GB 10k rpm in RAID5 where RAID is provided by internal DELL Power Edge RAID controller PERC 5/i (re-branded LSI MegaRAID SAS). Software provider has load tests which are able to recognized if system is good enough for requested solution. Software provider has reference hardware configuration with reference results. Reference hardware is server SuperMicro with eight 3.5" SCSI 36GB 10k rpm connected to RAID controller Areca ARC-1260. Disk subsystem is tested by real load test and also by synthetical disk benchmark utility "iozone". We can try to tune disk subsystem and check progress by synthetical benchmark tool.

RESULTS & TUNING
Here are results from reference hardware (SuperMicro):
1 THREAD
iozone -s 32g -r 1m -i 0 -i 1 -t 1 -b /tmp/test.xls
Initial write 299951.25 kB/s
Rewrite 254075.39 kB/s
Read 386271.91 kB/s
Re-read 388288.41 kB/s

2 THREADS
iozone -s 16g -r 1m -i 0 -i 1 -t 2 -b /tmp/test.xls
Initial write 327977.77 kB/s
Rewrite 321502.41 kB/s
Read 312530.73 kB/s
Re-read 315091.88 kB/s

10 THREADS
iozone -s 4g -r 1m -i 0 -i 1 -t 10 -b /tmp/test.xls
Initial write 293753.92 kB/s
Rewrite 281009.19 kB/s
Read 262086.25 kB/s
Re-read 260864.43 kB/s

Software provider tested DELL PE 2970 with these results:
1 THREAD
iozone -s 32g -r 1m -i 0 -i 1 -t 1 -b /tmp/test.xls
Initial write 339329.00 kB/s
Rewrite 325063.56 kB/s
Read 337726.91 kB/s
Re-read 320971.62 kB/s

2 THREADS
iozone -s 16g -r 1m -i 0 -i 1 -t 2 -b /tmp/test.xls
Initial write 356046.38 kB/s
Rewrite 359441.64 kB/s
Read 193787.55 kB/s
Re-read 194154.85 kB/s

10 THREADS
iozone -s 4g -r 1m -i 0 -i 1 -t 10 -b /tmp/test.xls
Initial write 296494.20 kB/s
Rewrite 281730.82 kB/s
Read 147723.06 kB/s
Re-read 148728.67 kB/s

We can see significant difference between reference hardware and DELL hardware. DELL is better in write throughtput but worse in read throughtput. Default parameters of DELL servers are preconfigured for database servers where are usually different requirements then for streaming applications. Streaming applications don't need write but read performace. DELL received request from software provider to optimize infrastructure for better read performance.

Tunning of disk subsystem is not easy task and it's depended on lot of aspects. In this particular environment we have OS Linux Debian 4.0 (kernel 2.6.x), filesystem XFS, Raid 5, PERC 5/i. Debian is not certified and supported operating system so customer cannot use standard DELL tech-support but sometimes DELL can help to their customers in some particular complex enterprise solutions.

For increase read performace - especially sequence reads - is very important to set up read-ahead cache. PERC 5/i can be in three modes - adaptive, read ahead and non-read ahead. PERC is by default in adaptive mode which means that PERC use internal algorithm to automaticaly recognize when to use read-ahead. In this particular solution we can explicitly set up "read ahead" mode in RAID management. Another very important point is to set up read-ahead in operating system Linux block device layer.

Linux kernel 2.6
Set the value to 8192 blocks using the blockdev command, for example
blockdev --setra 8192 /dev/sda
this example is setting up 4MB Cache (8192 blocks of 512-byte sector)
which is aligned with default XFS parameters see. xfs_info for current XFS parameters

DELL IOZONE tests reults on DELL PE 2970 with tuned block device layer:
2 THREADS
iozone -s 16g -r 1m -i 0 -i 1 -t 2 -b /tmp/test.xls
Initial write 290692.31 kB/s
Rewrite 359531.20 kB/s
Read 503044.62 kB/s
Re-read 496045.61 kB/s

10 THREADS
iozone -s 4g -r 1m -i 0 -i 1 -t 10 -b /tmp/test.xls
Initial write 297497.92 kB/s
Rewrite 279933.16 kB/s
Read 473969.33 kB/s
Re-read 481384.16 kB/s


CONCLUSION
It's possible to successfully tuned up disk subsystem by set up read-ahead parameters. Read throughtput of DELL PE 2970,PERC 5/i,8xhdd 10k rpm was increased approximately 3 times so we achieved great results in synthetical benchmark (iozone) and overcome reference hardware results. What we can see is that disk performance lowers with more concurrent threads. Local RAID controllers are designed as disk storage for one server where I/O stress is not so high. If someone is looking for storage without I/O stress issues he should focus to SAN disk arrays which are designed for environments with lot of servers, proceses and threads.