the birdhouse in my soul

SSD vendors like Samsung or Intel often provide tools to reserve some space on your SSD that can be used by the internal algorithms for better wear-leveling, longevity, garbage collection, and performance. My own Samsung SSD comes with a tool to do that on Windows, for example. But on vSphere, you'll have to do that manually: I see two possibilities: don't format the SSD "full" but instead use "partial", and specify only the amount of the disk that you want to use. The rest is left unpartitioned, and therefore unallocated. You can only do this if you haven't formatted the SSD as VMFS yet. If you have, this second possibility can still help you: create a thick-provisioned lazy-zeroed VMDK on the SSD-backed VMFS, either with vmkfstools or by creating a dummy VM. Those blocks are allocated, but remain unwritten. You're not going to attach the disk to a running VM, so they won't ever be written to. This effectively reduces the amount of blocks t...

Another post documenting a small issue just so I can google it later: one of the Cisco/Linksys WRT160NL devices (both running DD-WRT) in my environment stopped accepting config changes through its web interface. It happened to be the one I'm using as a NAT gateway and DHCP server, not the one just functioning as access point. A config backup appeared to be full of UPnP rules. Those are port forwarding rules that have been asked for by applications on NATed stations that want to be reachable. Think Skype amongst many others. Clearing the UPnP list solved the problem: click "NAT/QoS", then "UPnP", then "Delete all". Apparently the UPnP list filled up the available NVRAM space, which broke all subsequent config changes.

Imagine wanting to access a VM, but you don't know the IP address, and you don't have a GUI client for your vSphere environment? The most basic way of getting the IP address of a VM from the vSphere hypervisor level, is logging in to the ESXi Shell (could be local or SSH), and finding your VM number in the VM list: # vim-cmd vmsvc/getallvms In my example, my VM has number 42. Then type # vim-cmd vmsvc/get.summary 42 | grep ipAddress       ipAddress = "10.11.12.13",  Et voila! NB this requires running VMware tools in your guest OS, evidently.

Some time ago, a CentOS install on a particular new Dell workstation needed the "nomodeset" kernel parameter to get a graphical login screen to correctly display. This was with a Radeon Firepro 2260 graphics card. After applying the CentOS 6.3 updates, Xorg wouldn't correctly detect the LCD panel's resolution anymore. A 1680x1050 panel would get a 1280x1024 resolution. In the days of digital DVI connections, DDC probing and what not, this was unusual and surprising. A lot of searching and testing led to the solution: the nomodeset parameter broke Xorg probing. Rebooting without the nomodeset parameter worked (no graphical problems like I had earlier), and solved the Xorg resolution probing.

The newest addition to my home lab is a Synology RS3413xs+ NAS. While installing it, I came across a couple of details that I didn't know before buying it. So for other people thinking of buying this unit, here's what I found out: If you add network interfaces in the available PCIe slot, they might be numbered _before_ the four onboard interfaces. They were in my case. So onboard 1-4 are eth2-5, and add-on interfaces 1-2 are eth0-1.  the SSD cache feature only works with identical drives in the both cache slots. You can buy two 120GB SSDs, but you can't just add one 240GB SSD. Except if you configure it manually through the CLI, and want to work without Synology support.  as explained in an earlier post, there's no multiple-VLAN-over-one-interface support in the GUI, but you can work around that in the CLI the DSM web interface counts VLAN-tagged packets twice in its "Total Network" graph. The per-interface/per-bond counters are correct however. PS that loo...

Synology, like other SOHO/SMB NAS vendors, touts VLAN functionality with their current DSM 4.1 software. However, the web interface just lets you specify one VLAN tag to use over each eth interface (or bond interface). Manual approach In the busybox environment that you can ssh into as root (after enabling ssh through the webinterface), there's all the tools you need to use multiple VLANs over one link (eth or bond), however: First you insert the 802.1q module into the Linux kernel:  /sbin/lsmod | /bin/grep -q 8021q || /sbin/insmod /lib/modules/8021q.ko Then you add each VLAN you need to every interface (bond0 in this example)  /sbin/vconfig add bond0 4 And finally you can configure IP addresses on every interface.vlan combination (bond0.4 in this example)  /sbin/ifconfig bond0.4 192.168.4.1 broadcast 192.168.4.255 netmask 255.255.255.0 The same type of script would work on a QNAP NAS too, by the way. They offer 8021q.ko and vconfig in their commandline environment a...

Buying the right NAS device for a vSphere home lab is not an easy task. This blog post documents the decision process you should go through IMHO. First, decide which data you are going to put on it. Lots of people buy a NAS for secondary data only (I.e. backups), but in a home lab, there's probably primary data too. How important is the data , and do you require a backup of this primary data? Then, think about the volume of data you need. Is it 1TB, more like 5TB, or rather 10TB? Number three, protection level. No one wants to lose data, but how badly? Surviving one disk failure is a minimum, but a RAID5 set enters its "danger zone" when that happens. That means an additional failure will make you lose all the data on the set. The danger zone ends after you've replaced the failed disk and it's contents have been rebuilt. RAID6 enters the danger zone after losing a second device before the first is rebuilt. Kn ow your danger zone ! A fourth decision is spe...