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AWS command line tasks - Create 500 GB EBS Volume, to attach and detach the volume

To create a volume of 500 GB 
aws ec2 --region us-east-1 create-volume --size 500 --availability-zone us-east-1d --volume-type gp2

size : in GB
availability zone : This needs to be in the same availability zone as that of the instance that we are going to attach the EBS volume.

To attach an EBS volume to the ec2 instance.

aws  ec2 attach-volume --volume-id vol-9dfjhsdkfj93 --instance-id i-1234567899oasd  --device /dev/xvdb --region us-east-1

After attaching format the drive and mount it like what we do for a normal hard disk drive.

To detach an EBS volume from the ec2 instance.

aws ec2 detach-volume --volume-id vol-9dfjhsdkfj93 --region us-east-1


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Qmail cheat sheet

http://supportlobby.com/blog/category/technical/qmail-technical/

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1) To check the mail queue in plesk from command line, you can use the command :

 /var/qmail/bin/qmail-qstat
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2) You can examine the queue with qmail-qread.

/var/qmail/bin/qmail-qread
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3) From the qread command you get the message id . In the above example , let us assume one of the id is 524514 . Now you can find the file holding the email in/var/qmail/queue with find command.

# find /var/qmail/queue -iname 524514

/var/qmail/queue/remote/22/524514

/var/qmail/queue/mess/22/524514 (mail headers)

/var/qmail/queue/info/22/524514

4) From the mail header you get the IP address

vi /var/qmail/queue/mess/22/524514


Or

Shortcut for the cool guys
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find /var/qmail/queue -iname queu_id | grep mess | xargs less

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4) If you wish …

Logical volume vmxxxx_img is used by another device - Error on LVM removal

Hi Folks,

I've faced error while trying to remove an LVM from the server.

The exact LVM error will be "Logical volume vmxxxx_img is used by another device" on executing the lvremove command.

Feel free to remove the following steps to remove the LVM from the server.

Note: Please remember to replace <id> with your VMID in the below section.

----------------------------------------------------------
dmsetup ls dmsetup info -c xen-vm<id>_img dmsetup remove xen-vm<id>_img lvremove -f /dev/xen/vm<id>_img ----------------------------------------------------------

File system corrupted on the OpenVZ container.

It happens rarely but when it does, it is hard to handle. The OpenVZ VM's are usually stable in nature, but I've encountered situations where OpenVZ VM was showing file system error and was refusing to start.

You can follow the below steps to recover the VM.


1. ~# vzctl stop ctid

2. # ploop mount /vz/private/ctid/root.hdd/DiskDescriptor.xml
3. now do a df -h and you will get the ploop id for the VM.
4. fdisk -l /dev/ploop12345
5. e2fsck /dev/ploop12345p1
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