Four (4) Volume Per Physical Disk Limitation in Windows Home Server (WHS)

Categorized | Operating Systems

Four (4) Volume Per Physical Disk Limitation in WHS

Posted on 02 November 2009. Tags: Adaptec 3085, Adaptec 31605, Raid 5, WHS, Windows Home Server

Just as a note to anyone running multiple large disks in Raid 6 for Windows Home Server. I was setting up new Raid 6 arrays on the WHS this weekend, controlled by an Adaptec 31605 and was greeted by a nice error message. WHS is limited to four volumes per physical drive using basic discs. A quick search of the Adaptec site showed the problem and a proposed fix, dynamic disks. While this would be great under normal circumstances, WHS does not play well with dynamic disks.

Practically speaking, instialling Windows Home Server limits your arrays stemming from a disk to 8TB (2TB for non-GPT * 4 volumes = 8TB). As larger drives are used, the net effect is fewer drives can be utilized in RAID. Practically speaking with 2TB drives, one hits this wall at:

5x 2TB disks in raid 5
6x 2TB disks in raid 6
8x 2TB disks in raid 10

When setting up a WHS using RAID, remember these limits! As an astute reader will likely note, 2TB drives do not correlate to 2TB in usable capacity, so in theory one could use an additional disk in the above example to make exactly 8TB of storage available.

This post was written by:

Patrick Kennedy - who has written 284 posts on ServeTheHome.com.

Patrick has been running ServeTheHome since 2009 and covers a wide variety of home and small business IT topics. For his day job, Patrick is a management consultant focused in the technology industry and has worked with numerous large hardware and storage vendors in the Silicon Valley. The goal of STH is simply to help users find some information about basic server building blocks. If you have any helpful information please feel free to post on the forums.

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