Back to basics – RAID types
Posted by Askar Kopbayev on
November 8, 2016
If you ever worked in IT, you have heard the acronym RAID. RAID stands for Redundant Array of Independent (some call it Inexpensive) Disks. So, it basically refers to a group of disk logically presented as one or more volumes to the external system – a server, for instance.
The main two reasons to have RAID are Performance and Redundancy. With RAID, you can minimize the access time and increase the throughput of data. RAID also allows one or more disks in the array to fail without losing any data.
Manage VM placement in Hyper-V cluster with VMM
Posted by Romain Serre on
September 23, 2016
The placement of the virtual machines in a Hyper-V cluster is an important step to ensure performance and high availability. To make a highly available application, usually a cluster is deployed spread across two or more virtual machines. In case of a Hyper-V node is crashing, the application must keep working.
But the VM placement concerns also its storage and its network. Let’s think about a storage solution where you have several LUNs (or Storage Spaces) according to a service level. Maybe you have a LUN with HDD in RAID 6 and another in RAID 1 with SSD. You don’t want that the VM which requires intensive IO was placed on HDD LUN.
RAID: Parity RAID vs SSD
Posted by Anton Kolomyeytsev on
October 2, 2015
The post describes the history of RAID 5 and how it became obsolete at some point in time, just because HDD capacity grew at an enormous rate. It happened due to the chance of failure that grew to literal imminence when spinning disks reached TB scale, because the reading speed still had the same physical limits. Basically, creating a RAID 5 even with 1 TB disks would mean certain failure of the whole array and quite soon. The array technology was “saved” by an unlikely ally – the SSD. Being faster than hard disk drives in everything, they almost nullify the chance of the abovementioned failures. The post is written for everyday reader, not just engineers, and is quite comprehensive even without special knowledge and skills.