On today's show I'll
build a system with just over a terabyte of storage. That
storage space shows up as one giant drive.
What's a terabyte? A terabyte is an awfully big chunk of
zeros and ones. Consider:
- A megabyte is equal to 1,048,576 bytes (2 to the 20th
power).
- A gigabyte is equal to 1,024 megabytes. (2 to the 30th
power, or 1,073,741,824 bytes).
- A terabyte is 2 to the 40th power. This is approximately
1 trillion bytes (1,099,511,627,776 bytes, to be exact), or
1,024 gigabytes.
For a better picture of how big a terabyte is, visit Data Power of
Ten or Hunter
College's pages on computer memory.
Still not impressed by a terabyte of storage? Take a look
at this screenshot
to get an idea how big a terabyte is.
Put the system together
Maxtor was kind enough to loan us seven D540X
hard drives. Each packs a whopping 160GB of storage. Since
there are only four IDE slots on the motherboard, we had to
add additional ATA connectors. A pair of Promise
Ultra 133 TX2 ATA cards filled two PCI slots and gave us
connections for up to eight more drives. The cards support
48-bit logical block adressing so it supports drives bigger
than 137GB. The ATA on the mobo only sees 128GB of the drive,
so you lose 30GB. The drives show up as 152.66GB after
formating with the Ultra 133s.
Mounting eight hard drives inside a midtower case is a
nightmare. Most cases are designed to pack a pair of drives in
a 3.5-inch hard-drive rack, and perhaps two more in empty
5.25-inch drive bays. Since this wasn't a permanent
installation, I initially chose not to permanently mount the
drives in racks in the case, but Yoshi found this so
unappealing, he mounted all seven drives inside the case. A
full-size case makes it easier; you simply use drive rails to
mount the drives in the front of the case in the 5.25-inch
drive bays.
Yoshi also showed me that right clicking on My Computer and
selecting Manage leads you directly to the Computer Mangement
application. Select Storage/Disk Management to get the Disk
Management Console.
A huge power supply is a big plus, along with a number of
power splitters. The last time we tried a massive storage
project (our quest for a half-terabyte), the power supply in
the case simply wouldn't boot that many drives. We kept a
second power supply on tap for this attempt. A 500-watt power
supply is the best solution.
Dynamic disks
We spanned space on all eight drives into a single drive
that shows up as one drive letter, using the dynamic disk
storage in Windows XP Professional (Windows 2000 also supports
dynamic disk storage; Windows XP Home doesn't). Instead of
loading eight separate drives on our Windows PC, we have two
in our terabyte system: The C drive and a huge "second" drive.
A dynamic disk lets us span multiple hard drives under a
single drive letter. It's not a RAID array, it can't be
mirrored, and it's not fault tolerant. If one of the disks
goes down, you lose the whole thing. In addition, other
operating systems can't use the dynamic disk on your system. A
spanned dynamic volume is not particularly practical, at least
not if you're paranoid.
Dynamic disks are easy to create. In the Control Panel open
Administrative Tools (you might need to click on Performance
and Maintenance first). Double-click Computer Management, then
click Disk Management. You can select individual disks and
change their status. You still need a "basic" disk for the
boot sector. We partitioned off one section of one of the
drives just for that.
Microsoft has the basic rundown
on dynamic storage in Windows XP and a basic
how-to. There's also a ton of info in XP's help files.
The $64,000 question is, of course, how long before it
takes only one or two drives, instead of eight drives, to get
a terabyte of storage. When that time comes, we'll just have
to go for a petabyte.
