XVA won’t start after successful import

I converted a physical machine (Windows XP) successfully & imported to my XenServer with XenConvert. The import appears to be successful. However, when I start the machine, all I get is a black console screen with the following info:

Citrix XenServer
http://www.citrix.com
cirrus-compatible VGA is detected

Processor 1: Xen(R) Virtual CPU
XS Virtual IDE Controller Hard Drive (73GB)
XS Virtual ATAPI-4 CD-Rom/DVD-Rom

Boot device: Hard Drive – success.

Some licensed legacy application was running on this machine and we needed to eliminate any physical PC in Datacenter.
Else there was no need to import XP rather would have built new one.
Well after repeated reboot no success with the VM, searching the forum someone suggested to fix boot sector with Windows XP repair disk.
The iso of existing XP-SP3 didn’t offer repair screen since the original install didn’t match the iso file.

SystemRescueCd-x86-2.5.1 iso came handy, booted from this gentoo based linux distro and fixed the boot sector with “ntfsfix”.
Disconnected the iso and voila the VM booted successfully.

So far only the vm booted successfully, but any geek would guess that due to HAL changes between the physical and virtual, XP ends up in re-activation process.
Without network the VM cannot connect to internet.. how will i fix this.
look out for next blog post… 🙂

Why Linux always show high memory?

Have you ever wondered seeing high Linux memory utilization? Even if you are not running any memory intensive applications, top, sar always report above 90% memory utilization. Its because Linux uses free memory pool for caching disk blocks, so most of the free memory is  used for filesystem cache. But it frees up dynamically if an application requires real memory. You can get actual memory by using command free.

re-blogged from source

How To Whitelist Hosts/IP Addresses In Postfix

If you are administrating a mail server and use blacklists to block spam (like in this article: How To Block Spam Before It Enters The Server (Postfix)), you probably know this problem: from time to time your customers complain that they cannot receive emails from certain freemailers. Most often this happens because a freemailer was abused to send out spam and therefore got blacklisted. This short guide shows how you can whitelist such a mail server in Postfix to make your customers happy again.

I do not issue any guarantee that this will work for you!

If a blacklisted server tries to send mail to your server, you should find something like this in your mail log:

SMTP error from remote mail server after RCPT TO:<bla@example.com>: host mail.example.com [4.3.2.1]: 554 5.7.1 Service unavailable; Client host [1.2.3.4] blocked using dnsbl.sorbs.net; Currently Sending Spam See: http://www.sorbs.net/lookup.shtml?1.2.3.4

In this example, the mail server 1.2.3.4 is blacklisted and therefore blocked.

To whitelist that server, create the file /etc/postfix/rbl_override where you list all IP addresses or host names (one per line!) that you want to whitelist:

vi /etc/postfix/rbl_override

1.2.3.4 OK
1.2.3.5 OK
mail.freemailer.tld OK

After you’ve created/modified that file, you must run

postmap /etc/postfix/rbl_override

Next open /etc/postfix/main.cf and search for the smtpd_recipient_restrictions parameter. Add check_client_access hash:/etc/postfix/rbl_override to that parameter, after reject_unauth_destination, but before the first blacklist.

So if smtpd_recipient_restrictions looks like this now…

vi /etc/postfix/main.cf

[...] smtpd_recipient_restrictions = reject_invalid_hostname,<br />                               reject_unauth_pipelining,                               permit_mynetworks,                               permit_sasl_authenticated,                               reject_unauth_destination,                               reject_rbl_client multi.uribl.com,                               reject_rbl_client dsn.rfc-ignorant.org,                               reject_rbl_client dul.dnsbl.sorbs.net,                               reject_rbl_client list.dsbl.org,                               reject_rbl_client sbl-xbl.spamhaus.org,                               reject_rbl_client bl.spamcop.net,                               reject_rbl_client dnsbl.sorbs.net,                               reject_rbl_client cbl.abuseat.org,                               reject_rbl_client ix.dnsbl.manitu.net,                               reject_rbl_client combined.rbl.msrbl.net,                               reject_rbl_client rabl.nuclearelephant.com,                               permit [...]

… modify it so that it looks as follows:

[...] smtpd_recipient_restrictions = reject_invalid_hostname,                               reject_unauth_pipelining,                               permit_mynetworks,                               permit_sasl_authenticated,                               reject_unauth_destination,                               check_client_access hash:/etc/postfix/rbl_override,                               reject_rbl_client multi.uribl.com,                               reject_rbl_client dsn.rfc-ignorant.org,                               reject_rbl_client dul.dnsbl.sorbs.net,                               reject_rbl_client list.dsbl.org,                               reject_rbl_client sbl-xbl.spamhaus.org,                               reject_rbl_client bl.spamcop.net,                               reject_rbl_client dnsbl.sorbs.net,                               reject_rbl_client cbl.abuseat.org,                               reject_rbl_client ix.dnsbl.manitu.net,                               reject_rbl_client combined.rbl.msrbl.net,                               reject_rbl_client rabl.nuclearelephant.com,                               permit <br />[...]

That’s it! Restart Postfix, and you’re done:

/etc/init.d/postfix restart

source: http://www.howtoforge.com/how-to-whitelist-hosts-ip-addresses-in-postfix

Amazing product, technologies & things I use every day of my life.


Company

Purpose

Product

Apple

Communication

iPhone 3GS

Chevrolet

Transportation

SUV Blazer 1998

Citrix

Server Virtualization Home Lab

XenServer v6.2

Dropbox

Cloud Storage, Cross Platform Sync

Dropbox

EMC

Type2-Virtualization

VMware WorkStation v8.0

Essence

Wrist watch

Sapphire Tungsten

Evernote

Sync notes, capture anything, access anywhere

Evernote

Google

Search engine, personal email

Search, Gmail

HP

Personal Laptop

HP Pavilion DV6000

Microsoft

Virtual Machine OS

Windows 7 x64

Mobily

Cellular Provider

Alwaha: Prepaid Voice/Data 3G Sim

Mozilla

Browser

Firefox

Open Source

Personal Laptop OS

Ubuntu Desktop Linux  11.10

Others

Social Interaction

Facebook, Twitter, Linkedin & Pinterest

STC

DSL BroadBand & Landline Telephone

Mband Jood: 4 MB Plus Free Calls

 

And the list goes on and on and on and on…..

Next time more on individual product, technologies, things & favorites

Share yours.

A stuck and hang VM on Xenserver

Needed to upgrade the XenServer (v6.0) host memory, while shutting down the VM’s running on the host, i encountered, two of windows x64 guests stuck and hung while shutting down.
When attempted to force shutdown, it complained that “Another operation involving the object is currently in progress “

Goggling for the error found the following link which fixed the issue:
here and here

Here’s quote from one of the post that finally fix it for me (you need to login to server’s shell to execute the below command) :
1 – “xe vm-list” to get the uuid of the VM that is hung
2 – “list_domains” to list the domain uuid’s so you can determinethe domain # of the VM above by matching the uuids from this output with

the uuid for your VM from the previous command.
3 – “/opt/xensource/debug/destroy_domain -domid XX” where XX is the domain number from the previous command
4 – “xe vm-reboot uuid=XXXX –force” where XXXX is the uuid from the first vm-list command for your VM. (name-label may work but didn’t work this time for me so I used the uuid)

after following the above instructions almost worked but VM’s were still stuck however, adding a “xe-toolstack-restart” at the end took care of the problem.

With Linux 3.0 the Xen Hypervisor now can run natively with Dom0

“The Xen hypervisor now can run natively with Dom0 (Domain 0) privileges. This gives it, like Linux’s Kernel-based Virtual Machine (KVM), the ability to work at the lowest possible level of the Linux kernel. In practical terms this means Xen virtual machines should run faster.”

wow, virtualization i love it…

source: here

SSH login takes long time

recently i prepared RHEL AS4.8 server connected behind firewall, in DMZ.
the domain part of hostname of the server was reflecting the internet domain name and the local MS-AD Domain was <domain>.local
connecting to this nix box from ms-platform was taking pretty long time to login after username & password request.
Upon googling i found this link which solved my problem.

Add the following to /etc/ssh/sshd_config on your SSH server
UseDNS no
Then restart the ssh daemon and your pauses should be gone.

thanks community..