lvm

One thing you might notice after deploying the new VCSA 6.0 is that it now includes 11 VMDKs. If you are like me, you are probably asking why are there so many? If you look at past releases of the VCSA, it only contained two VMDKS. The first disk was used for both the OS and the various VMware applications like vCenter Server, vSphere Web Client, etc. and the second disk was where all the application data was stored such as the VCDB, SSODB, Logs, etc.

There were several challenges with this design, one issue was that you could not easily increase the disk capacity for a particular application component. If you needed more storage for the VCDB but not for your logs or other applications, you had no choice but to increase the entire volume. In fact, this was actually a pretty painful process because a logical volume manager (LVM) was also not used. This meant that you needed to stop the vCenter Server service, add a new disk, format it and then copy all the data from the old volume to the new. Another problem with the old design is that you can not apply Storage QoS on important data such as the VCDB which you may want on a faster tier of storage or putting your Log data on slower and cheaper tier of storage by leveraging something like VM Storage Policies which works on a per VMDK basis.

For these reasons, VCSA 6.0 is now comprised of 11 individual VMDKs as seen in the screenshot below.

Here is a useful table that I have created which provides the mappings of each of the VDMKs to their respective functions.

Disk	Size	Purpose	Mount Point
VMDK1	12GB	/ and Boot	/ and /boot
VMDK2	1.2GB	Temp Mount	/tmp/mount
VMDK3	25GB	Swap	SWAP
VMDK4	25GB	Core	/storage/core
VMDK5	10GB	Log	/storage/log
VMDK6	10GB	DB	/storage/db
VMDK7	5GB	DBLog	/storage/dblog
VMDK8	10GB	SEAT (Stats Events and Tasks)	/storage/seat
VMDK9	1GB	NetDumper	/storage/netdump
VMDK10	10GB	AutoDeploy	/storage/autodeploy
VMDK11	5GB	Inventory Service	/storage/invsvc

In addition, increasing disk capacity for a particular VMDK has been greatly simplified as the VCSA 6.0 now uses LVM to manage each of the partitions. You can now, on the fly increase disk space for a particular volume while the vCenter Server is still running and the changes will go live immediately. You can refer to this article here for the process as it is a simple two step process.

Here are some useful commands to get more details of the filesystem structure in the new VCSA.

lsblk

lsscsi

With previous releases of the VCSA, increasing disk capacity was not a very straight forward process. Even though you could easily increase the size of the underlying VMDK while the VCSA was running, increasing the guestOS filesystem was not as seamless. In fact, the process was to add a new VMDK, format it and then copy the contents from the old disk to the new disk as detailed in VMware KB 2056764. This meant with previous releases of VCSX 5.x, you would need to incur downtime of your environment and it could be also be quite significant depending on your familiarity with the steps mentioned in the KB not to mention the time it took to copy the data.

UPDATE (12/06/16) - For VCSA 6.5 deployments, please refer to the article here as the instructions have changed since VCSA 6.0.

The reason for this unnecessary complexity is that VCSA did not take advantage of a Logical Volume Manager (LVM) for managing its disks. In VCSA 6.0, LVM is now used to make it extremely easy to increase disk capacity while the VCSA is running. VCSA 6.0 further simplifies this by separating out the various functions into their own disk partitions comprised of 11 VMDKs compared to the monolithic design in previous VCSA releases. This not only allows you to increase capacity for specific a partition but you can also now attach specific storage SLA's using VM Storage Policies on specific VMDKs such as the Database or Log VMDK for example.

In the example below, I will walk through the process of increasing the DB VMDK from the existing 10GB to 20GB while the vCenter Server is still running.

Step 1 - Verify the existing disk capacity using "df -h"

Step 2 - Increase the capacity on VMDK 6 which represents the DB partition using the vSphere Web/C# Client.

Step 3 - Once the VMDK has been increased, you will need to run the following command in the VCSA which will automatically expand any Logical Volumes that have had their Physical Volumes increased:

vpxd_servicecfg storage lvm autogrow

Step 4 - Confirm the newly added capacity has been consumed

If you would like to learn more about the different VMDK structure in the new VCSA 6.0, I will be sharing more details in a future article.

Multiple VMDKs in VCSA 6.0?

Increasing disk capacity simplified with VCSA 6.0 using LVM autogrow