My IT Adventure
Some of my virtual machines used ISL logical SCSI controller. It’s not recommended for Red Hat 6 virtual machines. We need to change it to VMware Paravirtual SCSI controller.
Basically the steps is power off virtual machine, change the SCSI controller type, and power on. Then you lost operation system. 🙂
It’s easy to find a solution for this particular problem. VMware has a KB for this error. Somehow it’s not my case. I don’t know what’s the exactly root cause but you can try vMotion the virtual machine to other host and give a try.
Chinese Version
这个问题的解决方案很容易找到，VMware有一个知识库。但不知道为什么，我遇到的问题没法用此知识库解决。我通过vMotion虚拟机到其他ESXi 主机解决此问题，也不知道具体原因是什么。
I noticed UCS Manager got unexpected failover after we upgraded firmware to 2.2(2c). Looks like it hits a bug CSCuo11700. Firmware should be upgraded to 2.2.(3a) to fix the issue.
English Version
Again something wrong on ESXi 5.5! Please don’t upgrade VMware Tools to 5.5 if you have Debian or Red Hat Linux virtual machine on your ESXi 5.5 hosts. There is a unsolved bug on vmmemctl drivers (balloon driver) of VMware Tools 5.5 can lead to Linux virtual machine hangs.
Few weeks ago, our database virtual machines got randomly failed. There was error message “The CPU has been disabled by the guest operating system. Power off or reset the virtual machine.” on VM events. I didn’t find any abnormal on vmkernel, hostd and vm logs. Finally our Linux team identified it’s a Linux kernel bug. Please refer to BUG at block/blk-core.c:NNNN! in blk_requeue_request or blk finish_request.
The bug only present on RedHat 6 on ESXi 5.5 with VMware Paravirtual SCSI drivers.
There are lot of articles tell how to install and setup Nginx + PHP-FPM + MYSQL. But few talk about how to secure WordPress website on the infrastructure. If you are a Windows guy, you perhaps familiar with ACL, it’s similar in Linux world. A user or group has 3 essential permission: read, write or execute. Read this article to understanding how permission works on Linux.
It’s been a while since last technical post. I was pretty busy on preparation of holiday maintenance plan as well as few problems in virtual environment. There was one I’d like to share as it’s a sample to show how to ‘touch’ hardware layer from virtual layer. 🙂
My blog finally backed online!! Due to a updating issue on PhotoVPS infrastructure, my virtual machine ran into unstable since Monday. I didn’t notice it till Wednesday. The virtual machine got intermittently network connectivity issue, PhotoVPS engineers can only temporarily fix it. I was struggled by the situation, finally I decided order a new virtual machine on Krypt. Krypt is ideally place for me since they are VMware certified partner, they helps VMware improves vCloud products and develops in public cloud market. The network performance is also the greatest from North American to China in US service providers, they have dedicate bandwidth to China Telecom.
You probably will see similar issue below if you upgrade vCenter Server from 5.x to 5.5.
vSphere Client show following error when login to vCenter Server by domain account.
The vSphere Client could not connect to vCenter server. The server vCenter server took too long to respond. (The command has timed out as the remote server is taking too long to respond.)
Some people say China government blocked Google. But I think it’s not blocked. Chinese user is suffering a extremely slow access speed to Google websites actually. I guess China government reduced bandwidth to Google since I can access Google.com in my late night time.