Today I came across the following propertyCollector error message whilst trying to modify the VM Swapfile location for two hosts in my lab cluster. This pops up as soon as you select the Virtual Machine Swapfile Location settings under the Configuration tab for your host. Once you click Close, you then see Swapfile Location: as Getting Data… for an infinite period of time, and the Edit… option becomes greyed out and cannot be selected.
The same error occurred on both an ESX and ESXi host in the came cluster, both using the latest vSphere 4.1 build 582267. I am going to assume this can appear on older versions too.
The object has already been deleted or has not been completely created
Call "PropertyCollector.RetrieveContents" for object "propertyCollector" on vCenter Server "<servername>" failed.
You can see the error in the following screenshot:
This seems to occur because the host does not have any record, even a default, for the snapshot location. This only affected half the hosts in my cluster, where the other half were showing their defaults just fine.
The fix for this is very simple. I’m sure it could be implemented by multiple methods, but I used PowerCLI. Simply:
- Connect to the faulty host, e.g.:
Connect-VIServer <servername / ip>
- Validate that you can see your preferred datastore from that host:
- Manually set the datastore to your preferred DS:
Set-VMHost -VMSwapfileDatastore <datastorename>
- Go back to vCenter and you will find the new value reflected, and you can now edit the Virtual Machine Swapfile Location settings under the Configuration tab for your host:
If you have multiple hosts with the same issue, or indeed when simply making swapfile location changes across your cluster, you could of course script the above.
I’m not sure whether this applies to vSphere 5 as I have not come across it there to date.
While doing some lab testing and benchmarking for my upcoming VCAP-DCD exam I came across some interesting results when messing about with NFS and iSCSI using FreeNAS. I plan to re-run the same set of tests soon using the EMC Celerra simulator once I have it set up.
The results are from very simplistic testing using a simple buffered read test only (it would be reasonable to expect write times to be the same or slower, and this is just a quick test for my own info). For this I used the following sample hdparm command in some Ubuntu VMs:
sudo hdparm -t /dev/sda
A sample output from this command would be:
/dev/sda: Timing buffered disk reads: 142 MB in 3.11 seconds = 45.59 MB/sec
As this was a quick performance comparison I only repeated the test three times per storage and protocol type, but even with this simplistic testing the results fairly conclusive.
Test HW was based on my 24GB RAM ESX and ESXi cluster in a box solution [hence some results will be faster than you can achieve over a gig network as this is all running on one host] running under Windows 7 64-bit with VMware Workstation 8. Components are:
- 4x ESX/ESXi 4.1 hosts running in Workstation 8 with an SSD datastore. 4GB RAM and 2x vCPUs each.
- 1x FreeNAS 0.7.2 instance running in Workstation 8 with an SSD datastore and a SATA datastore. I use this over FreeNAS 8 as it has a significantly smaller memory footprint (512mb instead of 2GB). 1vCPU and 512 MB RAM.
- 64-bit Ubuntu Linux VMs running nested under the ESX(i) virtual hosts. 1vCPU and 512 MB RAM each.
Storage components are:
- SATA 2 onboard ICH10R controller
- 1x Crucial M4 128GB SSD (500MB/sec Read, 175MB/Sec Write)
- 1x Seagate 250GB 7200RPM SATA
The results of the testing are as follows:
|FreeNAS 0.7.2 w/ NFS
|FreeNAS 0.7.2 w/ NFS
|FreeNAS 0.7.2 w/ iSCSI
|FreeNAS 0.7.2 w/ iSCSI
As you can see, FreeNAS with NFS does not play nice with ESX(i) 4. I can confirm that I have seen stats and posts confirming these issues are not aparent in the real world, with NetApp FAS or Oracle Unified Storage (which is aparently awesome on NFS) but for your home lab, the answer is clear:
For best VM performance using FreeNAS 7, stick to iSCSI!
, EMC Celerra
So I completed my VMware vSphere: Design Workshop [V4.x] last August, but just a week after that my second daughter was born. 6 months (and many dirty nappies) later, I have finally gotten around to looking at taking the exam! I did consider simply waiting for the vSphere 5 DCD exams to be released, but considering how long the v4 exams took to be released, I don’t think it’s worth the wait just now.
I plan to take the exam in late March, giving me 8 weeks to prepare, so much like I did with my VCP5 Exam Prep Guide, I will post an expanding list of my VCAP4-DCD exam prep materials below, in the hopes that it may be of some help to others.
Prep Courses / Materials
- VMware vSphere: Design Workshop [V4.x]
Well worth the time (and money – paid for by my employer, advantages of being a permie!) in my opinion. It is basically an opportunity to sit down for three days and go through a fictional design, end to end, using all the VMware best practices and guides, whilst shooting the breeze with like minded individuals. The manual provided with this course is very good, and a few days prior to my exam I plan to read it again cover to cover.
- DRBC Design – Disaster Recovery and Business Continuity Fundamentals
Online “virtual” training course from VMware. Pretty steep price for only 4 hours training IMHO, especially when they only give you 3 months access… For $240 (£152) I would expect permanent access to it! Fortunately, again I didn’t actually have to pay for this myself. Were I contracting, I would seriously think twice about skipping this! I believe some people can access this for free, depending on your VMware Partner level.
- VMware vSphere Design by Forbes Guthrie, Scott Lowe and, Maish Saidel-Keesing
If there is one resource which I can recommend above all other’s it would be this book. Buy it on Kindle for less than £20! Its the best £30 you’ll ever spend!
- VMware vSphere 4.1 HA and DRS Technical Deepdive by Duncan Epping and Frank Denneman
A superb and easy read. This is a short book concentrating on the nitty gritty of vSphere clustering. You will need to know this if you want to pass the exam! Again, spread out your reading, and don’t try to take it all in in one go!
- Official Exam Blueprint
The official exam blueprint/guide. As much of a pain in the ar*e as it is, I suggest at least scanning through every document referenced in this guide. If you know it all (and have practiced it lots) then you *should* be ok in the exam!
- Exam Blueprint PDF Files and Objectives Discussion
Sean Crookston has very kindly packaged all the required PDFs up in an executable zip (based on 1.3 blueprint but its basically identical), thanks Sean! I wont have time to go through them all, but I’ll post a few highlights shortly. Also make sure that you go through his discussion on Objectives 1.1 / 1.2 / 1.3 / 2.1 / 2.2. I believe Sean would have done more but time constraints stopped him at that point, but what he has done is really useful and worth a read!
- VCAP4-DCD Exam UI Demo
A useful resource as this gives first-timers a chance to get used to the “Visio”-style exam interface and get an idea of the types of activities required in the exam. This requires registration, and only lasts 3 months from reg. Its disappointing that they do not give you sample exam questions for practice as you normally get with the VCP exams.
- VCAP-DCD4 Exam UI Tutorial
This one does not require registration and repeats the above without your interaction.
- VCAP-DCD Community Forums
I read through virtually every post on here (there aren’t that many). If you don’t want to read through them all (might take you an hour once you follow the links etc) I did take a note of some key comments which I felt were worth investigating later, which you can download here: VMware VCAP-DCD Community Forums Tips
- The Saffa Geek VCAP-DCA-DCD Guide
Gregg has a raft of links to prep materials, of which I plan to go through as many as possible.
- Private Cloud Architecture v1.4 by Iwan Rahabok
A superb resource with highlights for every area of design of what you should be considering.
- VCAP Brown Bags by Alastair Cooke et al. This is based on the VCAP-DCD5 (not yet out) but should still be applicable to VCAP-DCD4. Update: Having watched these, I can confirm that there are very few areas which are specific to vSphere 5, so I highly recommend you save these up and watch them as part of your final exam prep / review. You shouldknow most of it already if you have covered enough in studying, so with luck this should be a great way to do final revision.
- Overview, Methodology and Business Requirements
Excellent session where Alastair Cooke goes over the VMware VIM (Virtual Infrastructure Methodology). This is all just as relevant to vSphere 4 as it is to 5.
- Storage Design
A great reminder of the key things you need to remember when designing storage. Sometimes a bit hard to hear due to the VoIP method, but still a great presentation. Watch this when you are doing your final revision.
- Network Design
Much like the above. A good reminder session which very quickly goes through each key design choice and highlights pros and cons for each with a number of discussions based on live questions. Ran out of time after 75 mins so to be continued below.
- Availability and DR Design
Gladly, Alastair teaches this session himself, which is great as he is obviously a very good trainer. One great tip I gained was when defining your replication strategy for your RPO, don’t forget that the time to replicate must be within the RPO timescale, especially when using periodic replication. For example if your RPO is an hour, then your replication must complete within that hour. A 2 hour replication on a 1 hour RPO doesn’t meet requirements!!!
The closer your RPO gets to zero, the more likely you will need continuous replication. When under an hour, start to look into asynchronous replication. Once you’re getting into RPO times under 5 mins, you will probably start needing to look at synchronous replication, which obviously causes latency, and may dictate distance to your DR site etc.
- Security Design
Direct link from Vimeo as the main link page on demitasse.co.nz seems to be missing it. The detailed slide decks can be found here and here. One wee golden nugget was to use folders in the datastore view to lockdown permissions. A really simple use of this is to put all the local VMFS volumes into one directory and secure it, that way admins wont have to sift through them when creating VMDKs as they will not appear in their views, so this reduces risk of putting VMDKs in the wrong place.
- Network Design (Continued)
A simple continuation of the previous session. Only lasts 45 mins or so.
- Exam Registration and Environment
Skip the first 16 mins as its mainly about VCAP5 track. The next section (10 mins or so) can be summarised as:
- Multi Choice Questions
These make up over half exam
Small # of points per answer
No partial points – all or nothing!
- Drag and Drop Style Questions
Quite a few questions
Single digit points per answer
Partial points given, based on being correct with 2-4 key ideas.
- Visio-Style Design Tool
Might be 3-5 questions
Worth a lot of points per answer, e.g. 20-40 pts!
Partial points given, based on up to 20 checks against your design.
- Time Management Suggestion
Not sure if i’ll try this or not, I normally do exams straight through and dont look back!:
– Do all multi choice questions first.
– Second time through, do drag and drop questions.
– Third time through do design questions, which means you know how much time you have left.
- Host Design
Another great session run by Alastair Cooke. Quote of the day:
“Always document WHY you make a decision.”
- Cluster Design
Scheduled for 29 March 2012. Irrespective of my exam being over this week, I will be tuning in (though maybe not live as I think these run at about 6am for us in the UK)!
- Other Brown Bags – DO NOT MISS THESE!
- VCAP-DCD Objective 1 (Jason Boche) Absolutely SUPERB brown bag, do NOT miss this! This goes through the VMware design process, the info you need to gather, who from, and why. He then goes into how to identify Requirements, Constraints, Assumptions and Risks, and has a quick game of identifying each from some example cases. I cannot recommend this enough…
- vSphere Design with Harley Stagner
A great preparation tool to use closer to the time of your exam. This goes through a couple of design scenarios and discusses the different options you could consider. Definitely watch this!
- VMworld Community Sessions (2010)
Now free to watch if you sign up for a free account. I recommend you go through as many of the TA and BCtracks as you have time for (there are about 50 odd of them at about an hour each!!!) but if you only have time for a few, concentrate on the following in priority / technology order depending on what areas you are weakest on:
- TA8133 Best Practices to Increase Availability and Throughput for VMware
Superb presentation pitched at an appropriate level. Lots of good storage design tips here. If you don’t watch anything else, watch this!
- TA8018 Architecting for Performance
Only 40 minutes long. More of a refresher of things you should be remembering anyway, plus a couple of information nuggets. Watch it in your lunch hour.
- TA7171 Performance Best Practices for vSphere
Very good session led by Scott Drummonds, formerly of VMware, now EMC. Absolutely worth a watch! Covers ESX(i), Storage, Memory, NetIOC/SIOC, and a quick bit about troubleshooting.
- TA8065 Storage Best Practices, Performance Tuning and Troubleshooting
Detailed review of best practices by Duane Fafard from IBM. He goes through his whole design process from Fabric, to arrays, queue depths, pathing, and much more. The design stuff is based on IBM HW, but applicable on any vendor setup. A great presentation and some really useful tuning and troubleshooting tips.
- TA8452 Designing Resilient Networks for vSphere and NFS
This is audio only, but you can download the slide decks so no biggie. This is a good reminder session if you read Scott Lowe’s book, if not, it’s essential! The first ~25 mins are the most important, after which it all becomes very NetApp specific.
- TA8595 Virtual Networking Concepts and Best Practices
First of all, skip the first 20 mins which is very basic. Second, if you have already read Scott Lowe’s design book, the rest of this presentation should really just be a refresher. Nothing much new here.
- TA6841 Cisco Nexus 1000v: Architecture, Deployment, and Management
Run by Jason Nash of TrainSignal vSphere Security course fame, this presentation is an excellent into to Cisco Nexus 1000v. Doesn’t go into masses of detail (he only has 50 mins to be fair!), but still highly recommended. If you want more detail, try the TrainSignal course (at a cost!), or read the VMware white paper Guidelines for Implementing VMware vSphere 4 with the Cisco Nexus 1000V Virtual Switch.
- TA7121 Next Generation VM Storage Solutions with vStorage API for Array Integration (VAAI)
Just watch the first 20 mins for a quick overview of VAAI by the guy who wrote it! The rest talks about features which have basically come out in vSphere 5, though jumping to > 38 mins or so lets you hear the Q&A session which is quite interesting too.
- TA8440 10Gb & FCoE Real World Design Considerations
Some great best practice recommendations, along with some great info on NetIOC and recommendations for shares, etc. My only complaint is that the speaker is speaks VERY fast, which he does apologies for at the start, but its quite distracting. Definitely a good session though.
- TA7743 ESX iSCSI News, Configuration, and Best Practices
Some useful solutions for iSCSI multipathing, though the presentation is not that well done and jumps about a bit. You may be better just reading the iSCSI SAN Configuration Guide (vsp_41_iscsi_san_cfg.pdf), page 36 onwards.
- BC7803 Planning and Designing an HA Cluster that Maximizes VM Uptime
A great session part presented by the ever-knowledgeable Duncan Epping. If you haven’t read his HA book, don’t miss this! Be warned: some muppet who edited the video has left the muzak running in the background for the entire video! Just turn the volume down a lot until you can mainly only hear the presenters, and as little music as possible. Very annoying!
- MA7528 VMware vCenter Server: Operational Best Practices in the Datacenter
Covers a lot that you should already know if you read Scott Lowe’s book, but a decent presentation and some good reminders for the kind of questions to ask yourself in section 1 of the VMware “design framework”.
- BC8274 VMware Fault Tolerance – Best Practices, Usage Scenarios and Performance
Ok session, but most of this info you should already know. Skip the first and last 15 mins as they are very basic, and the Q&A session is poor as they don’t repeat the questions for the mic!
- SE8206 Security Hardening Guidelines for vSphere
This is not a guide to security, it’s a guide to the security guides!!! They do highlight some of the most important recommendations, from 21.5 mins onwards if you want to watch it, otherwise, just read the actual vSphere 4.0 Security Hardening Guide pdf, referenced in the 1.6 blueprint!
- BC8283 Backing up VMware – Benchmarked and Best Practices
- BC7773 VMware Site Recovery Manager: Misconceptions and Misconfigurations
An excellent presentation on SRM from the inimitable Mike Laverick of RTFM-ED. First 40 mins for the best DCD related content.
- BC6703 How to be Successful with SRM Implementations
An excellent technical and architectural presentation by Michael White of VMware. Dives into multiple areas of SRM and many best practice tips. Dont miss it if you want to learn more on SRM!
- BC9017 Customer Use Cases: Lone Star College and Weyerhaeuser
A quick 30 minute run through a couple of use cases. The Weyerhaeuser was far better in terms of actually going into detail on the SRM implementation, and lessons learned. Jump to 11:30 for this.
- EA7849 Design, Deploy, and Optimize Microsoft Exchange Server 2010 on vSphere
The blueprint is for 2007 but I think this presentation is still worth mainly seeing for the first half. Most of the stuff up until he starts discussing DAGs is relevant to 2007, plus you should be reading the Best Practices Guide: Microsoft Exchange Solutions on VMware, the Exchange Getting Started Kit, and Microsoft Exchange Server 2007 Performance on VMware vSphere™ 4 white papers anyway.
- EA7850 Design, Deploy, and Optimize Microsoft SQL 2008
This applies to 2005 or 2008 so is appropriate. Its a great presentation (skip the basics at start). Main point to note is that MS SQL DB Mirroring is the best method for virtualising SQL, though you do double your disk reqs as compared to MSCS. FT is also good for single CPU VMs with small, but critical DBs. The price to pay for flexibility! Dont forget the Best Practices Guide: Microsoft SQL Server and VMware Virtual Infrastructure and Performance and Scalability of Microsoft SQL Server® on VMware vSphere 4 white papers too.
- EA7061 Creating an Internal Oracle Database Cloud Using vSphere
Good presentation, but may not all be relevant. Key points are around licensing and suggesting that you have dedicated Oracle clusters if you have enough Oracle DBs. Dont forget the Oracle® Databases on VMware vSphere™ 4 and Virtualizing Performance-Critical Database Applications in VMware® vSphere™ white papers.
- EA8700 Oracle on vSphere: Re-Platforming Tier 1 Oracle Databases from UNIX to vSphere at Indiana University
Very interesting case study, which gives a good insight into architectural choices and methods for a migration between two DCs whilst also virtualising Oracle onto a different OS!
- SE7813 vShield Edge & Application Protection – Architecture and Use Cases
Interesting presentation, though the fist 15 mins or so are mainly marketing. Includes some use cases for things such as PCI compliance etc.
- TA2222 ESX implementation at Kroger Store Systems (from VMworld 2009)
Interesting case study with >100 remote sites controlled via a centralised vCenter in the main DC. Jump to 52 mins for architectural considerations, or read ROBO – Managing Remote ESX Hosts Over WAN with VirtualCenter.
- TA8661 Deploying vSphere in a ROBO Environment
Just read the pdf if you have watched TA2222. If you’re keen there’s an mp3 only presentation too with a few more tips and deep dive info.
- SE8421 Hypervisor-Based Antivirus and Endpoint Security
Ok presentation if you don’t know much about the vShield product suite. I downloaded the MP3 and listened to this one in the car. If you don’t have time, don’t bother.
- SE8389 Architectural Overview of Virtualization Security for the Private Cloud
This is basically a marketing presentation. Interesting, but basically not useful for study. I downloaded the mp3 and listed in the car to make my commute more exciting!
- TA6862 vDS Deep Dive: Managing and Troubleshooting
Interesting first half of the presentation, though not a huge amount of design help. Low priority for watching.
- TA8158 Surviving VMware on Blades
A little disappointing, and probably should have been in the partner presentations as half of it is a sales pitch! Useful only by examining the design decisions, and ignore the fluff. Skip the start and watch from 14 mins in.
- TA8270 Get the Best VM Density From Your Virtualization Platform
Don’t waste your time. This should have been in the 101 section.
- VMware Partner University Courses
Useful courses, if you have both access, and time:
- Infrastructure Virtualization Technical Post-Sales Accreditation: Assessment Fundamentals
Not much new here but just a few good reminders on how to size up your source capacity / requirements and only takes 1-2 hrs to complete. Also counts towards the Infrastructure Virtualization competency.
- More links to come…
VMware VCAP-DCD 4 Exam Review
, practice exams
, VMware Certification
, VMware Partner University
, VMworld Community Sessions