Rob/Doug Comments on the reply I got from a computational chemist colleague? If there really is a Sata I vs II issue the below suggests overall that it might be a red herring in that my read/writes are streamed, not random.
John ---------- Forwarded message ---------- From: Kalju Kahn kalju- -chem.ucsb.edu <[email protected]> Date: Sat, Dec 13, 2008 at 2:39 AM Subject: CCL: Hard drives and linux To: "McKelvey, John -id#3nu-" <[email protected]> Sent to CCL by: "Kalju Kahn" [[email protected]] Hi John, Couple of points: 1) I suggest RAID 0 for your scratch directory. I have 2X 500 GB WD SATA II disks as 1 TB linux softraid and I filled it yesterday with a single MP optimization job ... so do not get much less than this. With RAID 0 and newer disks you would be getting transfer rates at least 160 MB/sec, this is better than any single 10K RPM disk. 2) Do not worry about jumpers and buffer transfer rates of 150 (SATA I) vs 300 (SATA II). Your data transfers to disk surface will be less than 150 MB with current technology; the advertised 300 GB/sec transfer rate to 16 or 32 MB buffer is meaningless when you are writing gigabytes of integrals. But get a SATA II disk simply because this is how new disks are made nowadays. 3) There are two WD 1 TB green drives. The old WD10EACS is lousy, avoid this one. The newer WD10EADS (http://www.tomshardware.com/reviews/green-terabyte-1tb,2078.html) is a good choice if you are worried about power consumption and the machine is idle a long time (e.g. home computer that runs MP2 jobs part time. For 24/7 operation consider a pair of WD1002FBYS (Raid Edition 3, see http://www.tomshardware.com/reviews/hdd-terabyte-1tb,2077-8.html). With RAID 0 you should get hit over 200 GB/sec transfer rates. Hope this helps, Kalju
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