We often hear from people who are surprised that it is possible to cool 42 drives in a compact 4U enclosure, and it is a reasonable concern.
However, I can assure you that my design team spent many months experimenting with different configurations until we arrived at a design which would work.
Please allow me to point out a few things:
- ATA drives run much cooler than legacy Fibre and SCSI drives.
- There are three powerful blowers in the chassis and in fact we have tested the cooling with one blower failed at maximum workload and at the maximum allowable ambient temperature of 35C, to ensure that the disk HDA's never exceed the maximum recommended temperature in this failed state.
- Under normal operations, you can take off the lid and feel the drives to see for yourself that they are running at a reasonable temperature.
- Note that the airflow is unrestricted in the drive cage, as the drives are mounted vertically. If you have access to a smoke generator, you can see that the air flows between drives at a remarkable speed (thermal transfer is proportional to air velocity)
- Note that the spacing between rows of drives is asymmetric -- a design tactic which optimises thermal transfer from the drives to the airstream.
- We use blowers instead of fans, as when you have a design with high static pressure, only blowers can maintain their rated CFM (fans, commonly used in cheaper enclosures, lose efficiency if airflow is impeded in any way).
External-storage market continues to grow
Factory revenues for external disk storage systems grew 3.5 percent year-over-year to AU$4.4 billion in the third quarter of 2004, according to data released by IDC this week.
This is the sixth consecutive quarter of year-over-year revenue growth, according to the research company. The total disk storage systems market grew year-over-year as well, climbing 2.1 percent. Storage capacity also increased, by 50.5 percent year-over-year to 310 petabytes -- the largest growth rate over the past seven quarters.
Second place HP, which had 19 percent of the market, saw revenue dip 7.5 percent year-over-year. IBM came in third with 13.1 percent market share. NetApp posted the strongest year-over-year revenue growth during the third quarter, with 24.6 percent growth, says IDC.
EMC was also on top in the total networked storage market with 28.9 percent revenue share, followed by HP, with 23.3 percent, and IBM, with 11.5 percent. For the top ranking in the Open/iSCSI SAN market, HP and EMC differed by only 0.2 percent, the market researcher says.
IDC attributed the growth in the external disk storage market to increased adoption of entry and midrange networked storage, which it defines as storage priced below AU$150,000 per system. The top vendors introduced external storage systems and solutions targeted to specific customer and application segments during the third quarter.
In the network attached storage, or NAS, market, which grew 14.3 percent over the third quarter of 2003, NetApp led with 36.3 percent revenue share, followed by EMC with 34.8 percent share. HP was in the top position in the total global disk storage systems market with 23.6 percent revenue share, while IBM was in the second place with 20.6 percent share.
"We are encouraged to see continued growth in disk storage systems, despite the lower rate when compared to previous quarters," Brad Nisbet, program manager at IDC, says. "Conversely, we saw an increase in the growth of petabytes shipped, which is yielding the largest dollar per gigabyte pricing decline in seven quarters and points to a growing share of higher-capacity, lower-cost disk drive deployments and a broader variety of products offered by the major vendors."
