The Virtualization Practice

Author Archive for Greg Schulz

Greg Schulz
SSD options for Virtual (and Physical) Environments Part III: What type of SSD is best for you?

Part 1 of this series laid out the basics of nand flash SSD with part II discussing endurance and performance. This part looks at SSD options for virtual servers, vdi or virtual desktop as well as storage for physical server environments, your usage and configuration criteria will have a bearing on what type of SSD solution is best for you.

SSD options for Virtual (and Physical) Environments, Part II: The call to duty, SSD endurance

Let’s continue by taking a look at endurance for storing and retaining data using nand flash SSD. The importance of the first part of this series is to understand the basics of nand flash based SSD in order to make informed decisions on what is the best for your virtual or physical environment. In addition to SLC (high cost, improved duty cycles) and MLC (higher capacity, lower cost), there is also EMLC or Enterprise MLC which is striving for a balance between SLC and MLC characteristics.

SSD options for Virtual (and Physical) Environments: Part I Spinning up to speed on SSD

Solid-state devices (SSDs) are data storage memory (Figure 1) mediums that utilize semiconductor based memoires as opposed to magnetic media found in hard disk drives (HDDs) or magnetic tape. Semiconductor memories include ultra fast volatile dynamic random access memory (DRAM) commonly found as main memory (e.g. RAM) in servers along with and non-volatile memory (NVM) typically NAND flash. Nand flash based SSDs can be found in cameras (as SD cards), cell phones, iPods, and PDAs, as well as in notebooks, net books, laptops, tablets, and workstations. SSDs are also appearing in larger servers, appliances, and storage systems from consumer to enterprise level.

There are many enhancements and new features that are part of VMware vSphere V5.0 from a storage and I/O perspective (See VMware vSphere v5 and Storage DRS posts). One of those enhancements is a new Application Programming Interface (API) called VASA (vSphere Aware Storage API) which joins other VMware vSphere APIs some of which are shown in table 1. Note that there is a three letter acronym (TLA) shown in table 1 that is part of the VMware vSphere 5.0 release that can be confused with VASA called VSA (VMware Storage Appliance) however for now, let’s leave VSA for a future discussion.

Windows boot IO and storage performance impact on VDI

With Virtual Desktop Infrastructures (VDI) initiatives adoption being a popular theme associated with cloud and dynamic infrastructure environments a related discussion point is the impact on networks, servers and storage during boot or startup activity to avoid bottlenecks. VDI solution vendors include Citrix, Microsoft and VMware along with various server, storage, networking and management tools vendors.

A common storage and network related topic involving VDI are boot storms when many workstations or desktops all startup at the same time. However any discussion around VDI and its impact on networks, servers and storage should also be expanded from read centric boots to write intensive shutdown or maintenance activity as well.

Serial Attached SCSI (SAS) is better known as an interface for connecting hard disk drives (HDD) to servers and storage systems; however it is also widely used for attaching storage systems to physical as well as virtual servers. An important storage requirement for virtual machine (VM) environments with more than one physical machine (PM) server is shared storage. SAS has become a viable interconnect along with other Storage Area Network (SAN) interfaces including Fibre Channel (FC), Fibre Channel over Ethernet (FCoE) and iSCSI for block access.

The next true IT industry revolutionary product will be software, virtualization and cloud technology that does not require underlying physical hardware resources (servers, network and disk storage). While we wait for that revolutionary technology to appear outside of marketing or computer generated animations, there remains the need to protect cloud and virtual environments and their underling disk storage. Underlying disk storage includes among others solid state device (SSD) as well hard disk drive (HDD) and Removable Hard Disk Drive (RHDD) packaged in different types of solutions accessed via shared SAS, iSCSI, FC, FCoE or NAS.

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