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Technology Stocks : The New QLogic (ANCR) -- Ignore unavailable to you. Want to Upgrade?

To: George Dawson who wrote (23284)	7/11/1999 6:27:00 PM
From: George Dawson	Read Replies (1) \| Respond to of 29386

IOs for current FC drives: I looked up the stats on Seagates's Cheetah and Barracuda FC drives. I also looked up the stats for IBM's Ultrastar FC drives. Using the same methodology as the InfoStor author in my previous post (using the inverse of the seek time, rotational latency, and data transfer time the accesses per second doesn't yield any major differences between the Cheetah or the IBM drives. (the Barracuda is a 7200 rather than a 10,000 rpm drive). The real advantage of FC is apparent when you consider the number of disks clustered on an FC bus compared with the SCSI limit of 15. For a cluster of 40 disks you will get 4760 -> 5,080 IOs and this is beyond the limit of a single SCSI bus because of the device limit of 15 disks. Many commercial storage devices like the Sun A5X00 have disk and array patterns that exceed 15 disks (four arrays of 14 drives to three arrays of 22 drives). Sun's array compatability charts are described in terms of 200 GB devices (9.1 GB drives x 22) and server support ranges from 4 arrays for an NT server to 80 external arrays or 10 TB. George D.