Cost of Storage Often a Poor Justifier for Investment

It's sometimes argued that the high cost of hard disk storage is a good reason to invest in new auxiliary messaging technology, such as tape-based email archiving. However, some forms of disk storage are so cheap that such arguments may be invalid.

One of the things that trips up many people is the huge (more than 10x) price differential between:

  • The relatively small, high-performance (10-15 krpm), SCSI-interfaced, hot-swappable, hard drives employed in high-performance SAN/NAS subsystems; and
  • The cost of relatively large, moderate-performance (7.2 krpm), ATI-interfaced, hard drives employed in low-cost RAID5 arrays.

Here are some one-off price points from www.insight.com:

Low cost:

  • Seagate Barracuda 7200.8. Capacity 250 GB, ATA-100 interface, 100 MBps data transfer, 7200 rpm spindle speed. $87.71.
  • Maxtor DiamondMax Plus 9. Capacity 250 GB, SATA interface, 150 MBps data transfer, 7200 rpm spindle speed. $107.79.
  • WD Caviar SE WD2500JS. Capacity 250 GB, SATA II interface, 300 MBps data transfer, 7200 rpm spindle speed. $91.41.
  • Promise UltraTrak RM15000, 2 times Ultra160 SCSI 1 interfacing to 15 times ATT-133 RAID array. $3,769.99.
  • Promise VTrak 15110 - hard drive array, 2 times Ultra160 SCSI 1 interfacing to 15-x-SATA RAID array. $3,135.98.
  • Promise VTrak M500p - hard drive array, one Ultra320 SCSI 1 interfacing to 15-x-SATA II RAID array. $4,822.45.

Moderate cost:

  • IBM hard drive - 73.4 GB - Ultra320 SCSI, Capacity 73.4 GB, Ultra320 SCSI interface, 320 MBps data transfer, 15,000 rpm spindle speed. $399.99.
  • HP StorageWorks Modular Smart Array 1000 SAN Starter Kit. One Ultra320 SCSI 1 interfacing to 15-x-Ultra320 SCSI 1 RAID array. $12,499.98.

The bottom line is:

  • 3 terabytes of RAID5 low-cost storage = 15 times $107.79 = $1752.83 + $3135.98 = $4,888.81 using 7200 rpm ATA-100 drives; or
  • 3 terabytes of RAID5 low-cost storage = 15 times $91.41 = $1371.15 + $4822.45 = $6,193.60 using 7200 rpm SATA II drives; or
  • 3 terabytes of RAID5 moderate cost storage = 40 times $399.00 = $15,960.00 + 4 times $12,499.98 = $65,959.92 using 15,000 rpm Ultra320 SCSI drives.

Or for as low as $1.60 to $22 per Gigabyte.

... Nick Shelness

One Trackback

  1. By StorageMojo on June 30, 2006 at 12:55 PM

    Who Knew? Storage Costs Are All Over The Map

    In the elliptically named Cost of Storage Often a Poor Justifier for Investment Ferris Research performs a simple comparison of low-cost RAID 5 to what they call medium-cost RAID 5 for backing up corporate messaging systems. The bottom line: costs rang…

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