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--- guide:cloud:faq [2020/08/19 12:41]
kevin created
+++ guide:cloud:faq [2021/12/09 16:42] (current)
@@ Line 9: / Line 9: @@
     *[[guide:cloud:faq|FAQs]]
-======FAQ======
+======Technical FAQs======
+) ** Do you monitor my VM’s activity?**
+     Answer: We do not monitor user VM activity.
+) ** I cannot SSH into my VM which was working fine yesterday, do you know what happened?**
+     Answer: Please provide us more details about your VM in order to investigate. In the meantime, please
+     click on the Instance name in the Compute -> Instances tab, and then click on the Console tab to see
+     if there is any error output sent to the console.
+If you see messages like below it means that the kernel has hung and you will have to hard reboot the
+VM using the Actions drop-down menu.
+   [ 1920.399095] Not tainted 3.13.0-79-generic #123-Ubuntu
+   [ 1920.399559] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
+   [ 1920.400763] INFO: task apt-check:1286 blocked for more than 120 seconds.
+   [ 1920.401360] Not tainted 3.13.0-79-generic #123-Ubuntu
+   [ 1920.401820] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
+   [ 2040.400079] INFO: task rs:main Q:Reg:1061 blocked for more than 120 seconds.
+   [ 2040.400697] Not tainted 3.13.0-79-generic #123-Ubuntu
+   [ 2040.401132] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
+   [ 2040.401883] INFO: task apt-check:1286 blocked for more than 120 seconds.
+Basically, add these lines to "/etc/sysctl.conf":
+    vm.dirty_background_ratio = 5
+    vm.dirty_ratio = 10
+And then apply them:
+    sysctl -p
+A good reading describing these parameters can also be found here: https://lonesysadmin.net/2013/12/22/better-linux-disk-caching-performance-vm-dirty_ratio/
+) ** How can I save the changes I made to my VM, so I can use it later?**
+    Answer: You can snapshot your instance which saves its state into a new base image that you can use
+    later. The snapshot causes the instance to be paused temporarily and it's preferable to not have disk
+    activity while doing this, and the snapshot might even fail if the instance has (or had) a lot of data
+    written to it since it was started. Please see the User Guide section for more info on how to take a
+    snapshot.
+) ** I attached a large volume to my instance (10 TB), but when I try to format it takes a very long time. What can I do to make this step faster?**
+Answer: We recommend you format it as XFS and use the "-K" option:
+    mkfs.xfs -K /dev/vdb
+In our tests, it took around 3 min to format a 10 TB attached volume.
+) ** How do I give access to another user to my instance, without giving him access to my SSH private key?**
+Answer:You should never give another user access to your credentials or private key. Please run the following commands inside your instance in order to create a new user and allow him SSH key-based access to your instance. Replace "username" with your colleague's name.
+    sudo adduser username
+    sudo usermod -a -G users username
+    mkdir /home/username/.ssh/
+    chmod 700 /home/username/.ssh/
+    chown username:username /home/username/.ssh/
+    Obtain the user’s SSH public key and add it to his home directory: /home/username/.ssh/authorized_keys
+    chown username:username /home/username/.ssh/authorized_keys
+----
+**For More Technical Assistance**
+If you can’t find what you are looking for, please contact our support team. We are working hard to get back to you within 1-2 business days. Submit the ticket at [[http://helpdesk.chpc.ac.za|Helpdesk]]
+----
+====== Billing FAQs======
+) **I powered off my instance but I was still charged for usage!**
+     Answer: CHPC charges for resources allocated to the users whether they are actively using them or not.
+             The resources you were approved for are reserved for you therefore  you obligated to pay
+             for them.
+) **How often am I billed?**
+    Answer: CHPC will send out invoices on the 5th of every month for the previous calendar month usage.
+) **If I have an unpaid invoice, does that unpaid invoice get rolled in to the next months invoice?**
+    Answer: Yes.
+)** Why does my bill fluctuate each month even though I am consuming the same amount of resources each month?**
+    Answer: We charge for resources used per hour and the number of hours per month vary throughout the
+            year (28 days, 30 days, 31 days).
+) **Why am I not receiving an invoice?**
+    Answer: CHPC sends cloud resource usage invoices to all paying users on the 5th of every month.
+If you would like to terminate your account please email  [[https://users.chpc.ac.za/helpdesk/ |helpdesk@chpc.ac.za]]
+) **I have a billing related question that is not listed here, help?**
+Answer: Email [[https://users.chpc.ac.za/helpdesk/ | helpdesk@chpc.ac.za]] with your question!

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