|
Plenty of alternatives, plenty of confusion about storage for VMS
Recently I’ve seen a lot of confusion about what storage technology to use on multi-server video projects. Small, single server deployments are straightforward because local storage is normally a reasonable option and easy to deploy. The storage strategy for larger projects is more complex and dictated by many factors: the size of the project, the scope and scale of the existing infrastructure, and of course, the IT budget.
The first decision is choosing between a storage area network (SAN) and network attached storage (NAS). The factors affecting that decision have changed, as both SAN and NAS technology has evolved and virtualization has become a major factor. Network infrastructure may also be a decisive factor; especially if Fibre Channel fabric is already in place or if 10 Gig Ethernet is already in the plan. Still, this is as much a business decision as a technology decision.
A SAN is a block storage device. Any device that exposes its storage externally as a block device falls into this category such as an external hard drive or Direct Attach Storage (DAS). We call it an external hard drive when we attach it to a desktop. We call it a DAS when we attach it directly to a server. We call it a SAN when we add some form of networking, generally a switch and a fibre-based cabling system, between the device and the server that is consuming the storage. Common protocols for block storage include iSCSI and Fibre Channel. In the end, a computer attaching to a block storage device will always see the storage presented as a disk drive.
A NAS is a file storage device. This means that it exposes its storage as a network filesystem. So any computer attaching to this storage does not see a disk drive but instead sees a filesystem. Users and servers attach to the NAS primarily using TCP/IP over Ethernet, and the NAS has its own IP address. Common protocols for file storage devices include NFS, SMB / CIFS and AFP.
What separates block storage and file storage is the type of interface that they present to the outside world. Both types have the option of providing extended features beneath the “demarcation point” before they hand off the storage to the outside. Both may (or may not) provide RAID, logical volume management, monitoring, etc.
It is common today for storage devices to include both block storage and file storage from the same device. The EMC VNX Series is an example of a unified storage system. With unified storage, how the device is configured determines whether it behaves as block storage (SAN) or file storage (NAS).
This drives home the point that this is purely a protocol or interface distinction, not one of size, capability, reliability, performance and features.
Ultimately, both block or file storage can be used on your video project, but do not prematurely overlook file storage as the value proposition has significantly improved for projects of any size.
If you require more information regarding SAN and NAS analysis, click here for a more detailed article. Also, a whitepaper will be released as a supporting document with Aimetis 6.12 explaining this topic in more detail.
Sincerely,
Justin Schorn
VP Product Management
|