vSAN Storage Policies

I get a lot of questions about vSAN and its storage policies.  “What exactly does FTT mean?”, “What should I set the stripe to?”.  The default storage policy with vSAN is FTT=1 and Stripe=1.  FTT means Failures To Tolerate.  Stripe is how many drives an object is written across.

FTT=1 in a 2 node configuration results in mirror of all data. You can lose one drive or one node which results in 200% storage usage.  In a 4 node or larger configuration it gives you RAID 5 which is data being distributed across nodes with a parity of 1.

FTT=2 requires 6 nodes and you can lose 2 drives or 2 nodes.  This is accomplished through using RAID 6 which is parity of 2, and results in 150% storage usage.

If you want to check the status go to Cluster > Monitor > vSAN > Virtual Objects.  From here you can see the FTT and what disks it involves.  From the picture you can see with the 2 node vSAN cluster the objects are on both nodes resulting in RAID 1 or mirroring.

2017-08-30 12_36_08-vSphere Web Client

Now lets break  down which each setting is.

2017-08-28 10_01_51-vSphere Web Client

Striping breaks apart an object to be written across multiple disks.  In a all  flash environment there is still one cache drive per disk group, but it is used just to cache writes.  The rest of the drives are use for reads.   In a hybrid configuration reads are cached on the SSD, but if that data is not on the disk it will then be retrieved from the slower disks.  This will result in slower performance, but by having the object broken apart, and written across multiple disks it can result in increased read performance.  I would recommend leaving the stripe at 1 unless you encounter any performance issues.  The largest size an object can be is 255GB.  If it grows beyond that size it will be broken up into multiple objects across multiple disks.

Force provisioning allows an object to be provisioned on a datastore even if it is not capable of meeting the storage policy.  Such as you have it set for FTT=2, but the cluster is only 4 nodes so its only capable of FTT=1.

Object Space Reservation controls how much of an object is thick provisioned. By default all storage is thin provisioned with vSAN.  You can change this by increasing the percentage.  If you set it to 100% then the object will be thick provisoined.  You can set it anywhere between 0%-100%.  The only caveats are with deduplication and compression its either 0% or 100%.  By default the page file is 100%, but there is a command line setting you can change if you need to save this space.

Flash Read Cache reserves the amount of cache you want reserved for objects.  The max amount of storage the cache drive can use is 800GB.  If you have have 80 VM’s each with 100GB in storage then the entire cache drive storage is used.  When you power on the 81st VM the cache drive will not be able to give that VM any read cache.  That is why its best to not change the default unless you have a technical reason to.

 

How To Install vSAN Updates

VMware is making a lot of great progress with vSAN.  One of the biggest pain points with the technology is the daunting HCL.  VMware spends a lot of time working with hardware vendors to validate the various hardware and firmware versions with vSAN.  In the past this meant manually checking to verify you were running on the right firmware version.  Now with vSAN 6.6 it will automatically check if your running the correct firmware version, and if not you can download and install the firmware automatically.  I found one simple issue with this.  The buttons are not very clear about what they do.  As you can see from the below image it looks like those buttons would refresh the page.  The arrow points to the button that “updates all”.  By selecting that it will apply the update to all your host.  You can do this to all at once or through a rolling update.

2017-08-28 09_46_26-Pasted image at 2017_08_18 08_02 AM.png ‎- Photos

Strange Issues With Microsoft Clustering and ESXi

I have some legacy applications that require Microsoft Clustering which are running on ESXi 6.0.  Using Microsoft Clustering on top of VMware does not give you many benefits.  Things like HA and moving workloads across nodes is already available using virtualization.  What clustering does do is create more places for things to break and give you downtime.  Really the only benefit I see with clustering in a virtualized environment is the ability to restart a server for system updates.

RDM’s are required for using Microsoft Clustering.  RDM “Raw Device Map” gives the VM control of the LUN such as it was directly connected to it. To set this up you need to add a second SCSI controller and set it to physical mode.  Each disk must then share the same SCSI controller settings for every VM in the cluster. The negative side to doing this is that you lose such features as snapshot and vmotion.  When using RDM’s with physical mode you should treat those VM’s as if they were physical hosts.

12

The problem occurred when one of the clustered nodes was rebooted.  The node never came back online, and when checking the console it looked like the Windows OS was gone.  Powered off the VM and removed the mapped RDM’s.  When powering on the VM Windows booted up fine.  I Found that very strange so powered it off again and added the drives back.  That is when  I got the error invalid device backing.  VMware KB references the issue, and it basically says there is an issue with inconsistent LUN’s The only problem was I did have have consistent LUN’s.  I put in a ticket with GSS, and the first level support was not able to help.  They had to get a storage expert to help out. He quickly found this issue which was the LUN ID had changed. I am not sure how that occurred, but it was not anything I could change  When adding the drives in the VM’s the config it makes a mapping from the VM to the LUN.  When the LUN ID changed the mapping did not.  The only fix was to remove the RDM’s from all VM’s in that cluster and then add them back.

vCenter Fails after Time Zone Change

We recently changed our NTP server, and I needed to update all or hosts and vCenters.  I have a handy powershell script to update the ESXi hosts, but that script does not work on the vCenter servers.  I log into the server using port 5480 to gain access to the vCenter Management. I login as root and notice that the time zone is UTC.  I am in the Central time zone so I wanted to change it from UTC.  Turns out if you do that it break everything.  I had to learn this the hard way, and once I changed the time zone I was not able to log into vCenter.  I had to then go back and change the time zone back to UTC to regain access. Capture.

Only Default Printer Mapping Over With View 6.2

I recently had an issue with only the default printer being mapped over from the local Windows 7 PC to the View Client session.  It did not make any sense to me.  I had 10 printers mapped yet only 1 was showing up.  It turns out its a limitation of Windows 7.  If all the printers are using the same Driver and Port then you will only see the default printer under the Devices and Printers page.  If you right click that printer it will list all the printers you have mapped.  When you try to print something it will also list all your printers.

New Year New Goals for 2017

For the year 2017 I have 3 certification I would like to achieve.  Not only to advance my career, but to also further my knowledge and my passion for technology. Some people may feel that certification are not really necessary or serve no real purpose.  That you shouldn’t need a certification to just prove you know something,  certifications are a great way to containerize what you should learn about a subject.  I feel by not pursuing a certification I would not get as deep into learning about a technologies as I should.

AWS Certification is my first goal of the year. I think it is going to be an very important skill going forward in IT.  The cloud is everywhere and is constantly growing, and AWS is currently the market leader. I think of cloud as a automated way to run a data center.  When you need to accomplish something such as deploying a VM or provisioning networks, you do it by utilizing and automated tasks.  There are some real private clouds, but in general is seems most private data centers are still doing this the old fashion way.  Manually deploying new VM’s or configuring the network by hand.  That is why AWS is so important because they have already designed an automated way for you to deploy your workloads.  Leaving you to architect and design how to run your workload on top of it.  The real skill is knowing how to use AWS, and understanding the entire compute stack.  With understanding the entire stack  you can really go anywhere in IT.

Next on my list is the VCAP-6 DCV Implementation.  VCAP stands for VMware Certified Advance Profession.  Before you can pursue these certifications you must have first earned you VCP or VMware Certified Profession.  I have a real passion for virtualization, and I love everything that goes along with it.  My long term goal is  to accomplish the VCDX, but I know that is still very far off.   There are many steps to this goal, and VCAP is just one of many along that journey.  With the implementation certification I will show I understand how to fully deploy vSphere into the datacenter.  On the surface the  deployment does not really seem all that difficult until you realize how many settings or “nerd knobs” there are with it.  To accomplish this I hope to get some real off site training.  If this happens it will be the first time in my career that I will have had actual training on something.  I always find it ironic that companies are willing to spend millions of dollars on equipment, but not 5,000 dollars on actual training.  I will also use Pluralsight which I have a free subscription with for being in the vExpert program.  Thank you Pluralsight for giving that to us.  Finally I will read lots of blogs and white papers.  The VCAP tests cover so much that you really have to learn all you can before taking the test.  It shows that you have real knowledge and are a subject matter expert on it.

Finally my final goal for the year is VCAP6- DCV Design.  Design is probably one of the hardest parts of IT.  When  you ask what is the best way to do something the infamous answer in IT is “it depends”.  Because its not always a one size fits all.  Best practice does have its place, but the real knowledge is knowing what the best way to do something, and not just the best practice.  I think that this test will be the hardest for me.  My career has always been focused on the doing and the the designing.  It will be a learning curve, but will be good challenge and really further my skills.

Accomplishing these 2 VCAP test will give me the VCIX or VMware Certified Implementation Expert.  Proving that I now have the knowledge to deploy vSphere in the Data Center.  Hopefully I will be able to accomplish all 3 of these goals within the year of 2017.  If I do then maybe I will move on to the VCIX-DTM or some other challenge.  If you have any career advice please leave a comment below.  Thanks for reading this post and have a good 2017.

vCenter Server Resource Missing or Invalid

Recently I was trying to deploy an OVA file.  After selecting the storage I recieved the following error. capture

I tried downloading the OVA again, but still had the same issue.  Luckily it was an easy fix.  I was trying to deploy the OVA at the Cluster level.  What I needed to do was deploy the OVA at the ESXi level in vCenter.  Hopefully in a future vSphere update this will no longer be an issue.

VMware Quick Tip: Installing a VIB

Usually you use VMware Update Manager to install VIB’s such as Dell’s Open Manage.  You can also SSH into a host and use ESXCLI.

First upload the Offline .Zip file to your datastore.  Then you will need to find the mount point.

esxcli storage filesysem list

Now that you install the VIB.

esxcli software vib install -d “/vmfs/volumes/Datastore/DirectoryName/PatchName.zip

Now verify

esxcli software vib list

 

Blog at WordPress.com.

Up ↑