Tag: VDI

How to avoid VDI boot storm problems using SSD

Desktop virtualization, or virtual desktop infrastructure (VDI), can bring many benefits to an IT organization, including easier system management and centralized security and data protection. But the storage environment that supports VDI requires some careful planning to avoid the problem of VDI “boot storms” — big slowdowns that can occur when a lot of users log into the system at the same time. There are a few options for addressing the problem, but the one that makes the most sense relies on tactical placement of solid-state drives (SSDs).

The problem of VDI boot storms is a fairly straightforward one. Virtual desktop workloads are predictable; they’re based on the work hours of desktop users, which typically run from about 8 a.m. to 5 p.m. each workday. The overall storage I/O that an average virtual desktop generates is quite low compared with that of a server workload, and so the density of desktop virtual machines on a host is typically much greater than with server virtualization. Conversely, the initial startup of a desktop is very resource-intensive, where the operating system and applications do a large amount of reading from disk while loading and executing.

A boot storm occurs when many virtual desktops all boot up during a short window of time (for example, between 8 a.m. and 9 a.m.), which causes intense concentrated storage I/O that can easily overwhelm a storage subsystem. If the storage subsystem isn’t designed to handle the heavy I/O load, you can effectively end up with a denial-of-service attack on your storage subsystem.

Read the full article at searchvirtualstorage.com…

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Managing storage for virtual desktops

Implementing a virtual desktop infrastructure (VDI) involves many critical considerations, but storage may be the most vital. User experience can often determine the success of a VDI implementation, and storage is perhaps the one area that has the most impact on the user experience. If you don’t design, implement and manage your VDI storage properly, you’re asking for trouble.

VDI’s impact on storage

The biggest challenge for storage in VDI environments is accommodating the periods of peak usage when storage I/O is at its highest. The most common event that can cause an I/O spike is the “boot storm” that occurs when a large group of users boots up and loads applications simultaneously. Initial startup of a desktop is a very resource-intensive activity with the operating system and applications doing a lot of reading from disk. Multiplied by hundreds of desktops, the amount of storage I/O generated can easily bring a storage array to its knees. Boot storms aren’t just momentary occurrences — they can last from 30 minutes to two hours and can have significant impact.

After users boot up, log in and load applications, storage I/O typically settles down; however, events like patching desktops, antivirus updates/scans and the end-of-day user log off can also cause high I/O. Having a data storage infrastructure that can handle these peak periods is therefore critical.

Cost is another concern. The ROI with VDI isn’t the same as server virtualization, so getting adequate funding can be a challenge. A proper storage infrastructure for VDI can be very costly, and to get the required I/O operations per second (IOPS) you may have to purchase more data storage capacity than you’ll need.

Expect to spend more time on administration, too. Hundreds or thousands of virtual disks for the virtual desktops will have to be created and maintained, which can be a difficult and time-consuming task.

Read the full article in the March 2011 issue of Storage Magazine…

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