I thought that most people would have seen this awesome fling by now, but I received a couple of questions if it was already possible to migrate from the Windows vCenter Server to the vCenter Server Appliance. Surprisingly enough as William Lam wrote an excellent blog post on this subject. Anyway, this blog is just a simple short pointer to the Windows vCenter to vCenter Appliance migration tool and to William blog post. Read it, and go for it!
For those who weren’t able to attend the VMware Online Technology Forum live, the recordings are available for replay now including the Q&A sessions. If you are interested in what’s new for vSphere, VSAN, NSX, vRealize Operations, View and much much more make sure to tune in. Great way to get an overview and a better understanding of what vSphere has to offer. Click the image below to go to the OTF website, register (if you haven’t yet) and get access to a lot of free cool content!
When I joined VMware and had read a white paper on memory reclamation techniques a dozen times. I was left with a bunch of questions still and I emailed the engineer who authored it back in the days. I asked him a couple of “simple” questions and received a one pager email full with answers. Even the email I had to read twice. Not because it is insanely complex, but because there was so much information in there that it was impossible to digest at all. Carl Waldspurger was that engineer. I’d seen some of his talks when he was still at VMware but he has gone “dark” for a while.
Carl joined CloudPhysics in the early stages of the company. He has been working on various projects, and one of those projects is called SHARDS. I had not seen the result yet, and a couple of weeks ago I watched the presentation. Excellent presentation skills, but more importantly amazing research with a very important result. Some people may have been wondering what you can do with a platform like CloudPhysics and what you can harvast from the data, well I think it is fair to say that this is one of the results of all the hard data mining work that has been done over the last years. Here is the abstract with a link to the online presentation. I didn’t want to share everything here to drive some traffic to Usenix as support. Before you watch the video, a warning…. this isn’t a high level overview, serious deep dive.
Reuse-distance analysis is a powerful technique for characterizing temporal locality of workloads, often visualized with miss ratio curves (MRCs). Unfortunately, even the most efficient exact implementations are too heavyweight for practical online use in production systems.
We introduce a new approximation algorithm that employs uniform randomized spatial sampling, implemented by tracking references to representative locations selected dynamically based on their hash values. A further refinement runs in constant space by lowering the sampling rate adaptively. Our approach, called SHARDS (Spatially HashedApproximate Reuse Distance Sampling), drastically reduces the space and time requirements of reuse-distance analysis, making continuous, online MRC generation practical to embed into production firmware or system software. SHARDS also enables the analysis of long traces that, due to memory constraints, were resistant to such analysis in the past.
We evaluate SHARDS using trace data collected from a commercial I/O caching analytics service. MRCs generated for more than a hundred traces demonstrate high accuracy with very low resource usage. MRCs constructed in a bounded 1 MB footprint, with effective sampling rates significantly lower than 1%, exhibit approximate miss ratio errors averaging less than 0.01. For large traces, this configuration reduces memory usage by a factor of up to 10,800 and run time by a factor of up to 204.
You can find the slide/paper and video below as a download.
I am currently updating the vSphere Metro Storage Cluster best practices white paper, over the last two weeks I received various questions if there were any new recommendation for vMSC for 6.0. I have summarized the recommendations below for your convenience, the white paper is being reviewed and I am updating screenshots, hopefully will be done soon.
- In order to allow vSphere HA to respond to both an APD and a PDL condition vSphere HA needs to be configured in a specific way. VMware recommends enabling VM Component Protection. After the creation of the cluster VM Component Protection needs to be enabled.
- The configuration for PDL is basic. In the “Failure conditions and VM response” section it can be configured what the response should be after a PDL condition is detected. VMware recommends setting this to “Power off and restart VMs”. When this condition is detected a VM will be restarted instantly on a healthy host within the vSphere HA cluster.
- When an APD condition is detected a timer is started. After 140 seconds the APD condition is officially declared and the device is marked as APD time out. When the 140 seconds has passed HA will start counting, the default HA time out is 3 minutes. When the 3 minutes has passed HA will restart the impacted virtual machines, but you can configure VMCP to respond differently if desired. VMware recommends configuring it to “Power off and restart VMs (conservative)”.
- Conservative refers to the likelihood of HA being able to restart VMs. When set to “conservative” HA will only restart the VM that is impacted by the APD if it knows another host can restart it. In the case of “aggressive” HA will try to restart the VM even if it doesn’t know the state of the other hosts, which could lead to a situation where your VM is not restarted as there is no host that has access to the datastore the VM is located on.
- It is also good to know that if the APD is lifted and access to the storage is restored before the time-out has passed that HA will not unnecessarily restart the virtual machine, unless you explicitly configure it do so. If a response is desired even when the environment has recovered from the APD condition then “Response for APD recovery after APD timeout” should be configured to “Reset VMs”. VMware recommends leaving this setting disabled.
I was reviewing a paper on vCenter availability for 6.0 and it listed a watchdog service which monitors “VPXD” (the vCenter Server service) on the vCenter Server Appliance. I had seen the service before but never really looked in to it. With 5.5 the watchdog service (/usr/bin/vmware-watchdog) was only used to monitor vpxd and tomcat but in 6.0 the watchdog service seems to monitor some more services. I did a “grep” of vmware-watchdog within the 6.0 appliance and the below is the outcome, it shows the services which are being watched:
ps -ef | grep vmware-watchdog root 7398 1 0 Mar27 ? 00:00:00 /bin/sh /usr/bin/vmware-watchdog -s rhttpproxy -u 30 -q 5 /usr/sbin/rhttpproxy -r /etc/vmware-rhttpproxy/config.xml -d /etc/vmware-rhttpproxy root 11187 1 0 Mar27 ? 00:00:00 /bin/sh /usr/bin/vmware-watchdog -s vws -u 30 -q 5 /usr/lib/vmware-vws/bin/vws.sh root 12041 1 0 Mar27 ? 00:09:58 /bin/sh /usr/bin/vmware-watchdog -s syslog -u 30 -q 5 -b /var/run/rsyslogd.pid /sbin/rsyslogd -c 5 -f /etc/vmware-rsyslog.conf root 12520 1 0 Mar27 ? 00:09:56 /bin/sh /usr/bin/vmware-watchdog -b /storage/db/vpostgres/postmaster.pid -u 300 -q 2 -s vmware-vpostgres su -s /bin/bash vpostgres root 29201 1 0 Mar27 ? 00:00:00 /bin/sh /usr/bin/vmware-watchdog -a -s vpxd -u 3600 -q 2 /usr/sbin/vpxd
As you can see vmware-watchdog is ran with a couple of parameters, which seem to different for some services. As it is the most important service, lets have a look at VPXD. It shows the following parameters:
What the above parameters result in is the following: the service, named vpxd (-s vpxd), is monitored for failures and will be restarted twice (-q 2) at most. If it fails for a third time within 3600 seconds/one hour (-u 3600) the guest OS will be restarted (-a).
Note that the guest OS will only be restarted when vpxd has failed multiple times. With other services this is not the case as the “grep” above shows. There are some more watchdog related processes, but I am not going to discuss those at this point as the white paper which is being worked on by Technical Marketing will discuss these in a bit more depth and should be the authoritative resource.
** Please do not make changes to ANY of the above parameters as this is totally unsupported, I am mere showing the details for educational purposes and to provide a better insight around vCenter availability when it comes to the VCSA. **