Opt Partition Expansion

Title: Expansion of opt partition in the VM environment.

Category / Product: Skyhigh Secure Web Gateway VM Appliance.

Summary: 

This article helps customer to increase the opt partition of SWG without touching the web cache partition. This is possible only in VM based SWG , and will not work on On Prem . /opt directory holds significant importance in the filesystem layout. It provides a designated location for optional software installations, packages , separating them from the core operating system components.

 The df -h /opt command displays the size of the /opt directory, how much space is used, and how space of that is available (free), and the location where the /opt directory is mounted.

There could be multiple reasons for /opt to run out of space like user-defined logs, temp files, tracing files etc.  It is very normal for MWG to create mwg-core temp files in this directory while it is downloading and scanning files. If this directory is the source of your disk space usage on /opt, it could be that many large files are being downloaded at that time. It can be found in /opt/mwg/tmp direcotory. 

In the above Snip we could see the /opt directory used is 44% , at some point it was 100% leading to crash of the appliance. Here Cache Sizing is proper, hence we wont do the cache resizing.  Refer the article for Cache Resizing:

https://success.skyhighsecurity.com/Skyhigh_Secure_Web_Gateway_(On_Prem)/Best_Practices/Hardware_and_Appliance_Maintenance/Resize_a_Partition#What_is_partition_resizing_and_why_would_I_want_to_do_it.3F

Solution 

If it is a virtual environment, we can increase the /opt folder when we increase the existing HARDWARE DISK size, say 200 to 220 GB (This is Example) , without rouching Cache Partition

Virtual Environment Steps:

   "lsblk shows how many PV and VG are there with corresponding LV." 

1.  Extend the existing HDD size, say from 200GB to 220GB.

2.  Turn on the appliance and enter the terminal 

3.  Use "cfdisk"
      It should show the increased volume size as free in the last

4.   Use the arrow button and select the free volume. Make one new primary partition, say sda3, and save it. 

5.   Once done, extend the VG group. using "vgextend vg00 /dev/sda3"

   output :
                      The physical volume "/dev/sda3" was successfully created.
                      Volume group "vg00" was successfully extended.
                              i: to check the VG group "vgdisplay" 
                              ii: to check logical volume member "lvdisplay"
                              iii: to check the physical volume "pvdisplay"

6.   Once VG is increased, we can increase the opt using "lvextend -L +20G /dev/vg00/opt."
   
    output :
                      The size of the logical volume vg00/opt changed from 40.08 GiB (10261 extents) to 60.08 GiB (15381 extents).
                      Logical volume vg00/opt was successfully resized.

7.  "df -lH" shows the current size. 

Note: We can increase the opt partition as needed, but it is recommend to increase based on the HOST (vmware esx). 

Monitoring /opt partition as Precautionary Measure:

 A best practice for monitoring /opt is to configure alerts to trigger when /opt usage reaches a specific threshold. This can help you avoid problems before they happen. Below are some of our recommended methods to trigger alerts:

1. Incident IDs: Dashboard alerts are presented when the /opt partition usage exceeds 90%.

2.  Create a Rule to Monitor and Send Alerts. Policy > Rule Sets  > Error Handler > Default > Monitoring rule set.