Windows Tip: Windows Vista and GPT disks

Send your Windows question to Mitch today! | See other Windows tips



Windows Vista supports two types of disk partitioning: Master Boot Record (MBR) and Globally Unique Identifier Partition Table (GPT). GPT disks offer several advantages over MBR disks including more partitions (128 instead of 4) and larger partition sizes (theoretically up to 18 exabytes or about 18 million terabytes). But before you run out and get a zillion terabyte drive for your Vista workstation so you can store all your YouTube videos, you need to know the following.



First, Vista only supports NTFS-formatted disks up to 256 TB in size. While that's a lot, it's still only a tiny fraction of an exabyte. So maybe you won't be able to store all those videos after all.



Second, Vista can only boot from a GPT disk if your system uses Extensible Firmware Interface (EFI) instead of BIOS. But you can always have GPT data drives even if your system drive is MBR.

But third and most importantly, you must be aware that if the dirty bit somehow gets set on your humungous GPT volume, chkdsk.exe is going to take a darned long time to run. In fact, with your typical 1 terabyte LUN having millions of files, chkdsk will likely take several hours to finish. So if you're dreaming of having dozens of terabytes at your fingertips someday, think again. Would you really want your system to be locked into checking disk integrity for several days while you twiddle your thumbs?

Storage capacities for desktop systems have been growing at a tremendous rate in recent years, but chkdsk performance hasn't been able to keep up with this growth. A workaround is to use DFS to create multiple smaller volumes on your storage device and then create a namespace to logically unite these volumes into a single large volume. This doesn't really solve the problem however, but solid state hard drives may eventually shift the balance in this regard. Meanwhile, why not delete those old videos from your hard drive to free up some room?