Measuring storage performance on Linux systems can be done using multiple tools. However, there is one set of tools that comes stock with Linux. These are blktrace and blkparse. These tools trace SCSI commands and data flow through the kernel from request to final write. These tools even show states most people do not know about, such as IO splits. Here is a short tutorial on how to use these tools to collect a trace. If you upload that trace to The Other Other Operation’s workload repository they’ll analyze it and post some results. You’ll help The Other Other Operation make better benchmarks and learn about how your application actually uses storage.
Optimizing WordPress — Take III
I have written in the past about steps I have taken to optimize WordPress. There are now newer steps to take. Optimizing WordPress addresses the time it takes to render a page, as well as the scores you get via various scoring tools. The goal is to have a fast site, one that displays quickly without error. Unfortunately, that is often at odds with the UI tricks we want to use.
vSphere Upgrade Saga: 6.5 — Not Yet, But …
At the moment, I am waiting for several updates on VMware products to allow an upgrade to vSphere 6.5. Specifically, I am waiting on an upgrade of NSX and VIN that are supported by vSphere 6.5. The other tools I use should be fine with 6.5, but without those, I cannot upgrade. The vSphere Upgrade Saga continues with the following updates.
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vSphere Upgrade Saga: iSCSI Woes
I run multiple iSCSI servers, ranging from HPE StoreVirtual (must trusted) and Synology Server (tertiary server) to my own CentOS 7 base iSCSI server (least trusted). All run over 10GB links. In general, iSCSI usually works quite well. But for some reason, my CentOS 7 iSCSI server would cause the management agents to fail and vSphere to disconnect from vCenter. This would go on until the iSCSI server was shut down. I use those 10TBs of storage for testing data protection tools and for emergencies. This is a bad thing for the continued support of generic iSCSI. This is also a vSphere Upgrade Saga entry.
vSphere Upgrade Saga: vCSA Helper VM, Part 2
Currently, the VMware vCenter Server Appliance (vCSA) requires a Windows helper VM. This helper VM can be loaded with a number of different items, most notably vSphere Update Manager (VUM) and VMware Horizon View Composer. The services this VM can contain are listed later in this article. Suffice it to say, the helper VM (or VMs) become critical to your environment. I was running W2K8 R2 but decided to move to W2K12 R2. This was more of an effort than I had imagined. Most things worked just fine, but it took a bit of research to find out why some items did not work. See my previous article vSphere Upgrade Saga: vCSA Helper VM for the first part of this series.
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vSphere Upgrade Saga: VSAN Try 2
In my previous vSphere Upgrade Saga post, VSAN Upgrade Woes, I discussed upgrade problems in a relatively unsupported configuration. I finally figured out why I had such a problem. It was not the unsupported nature of the configuration, but the disk space used within VSAN. In effect, my VSAN was heavily overcommitted, and as such, there was no room to move things around to allow updates. I needed a new implementation of VSAN, one that is supported.