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CustomDesigned's Journal: "Green" drives fubar servers 1 1

Laptop hard drives have long come with power saving features. This makes sense for laptops, which are generally single user systems. I just had the misfortune of installing a pair of "green" WD5000AADS-00M2B0 drives in a server. I soon noticed the problem of rapidly rising Load_cycle_count acknowledged at the WDC Faq.

The fundamental problem with these "green" drives is that they assume a single user system. This was an OK assumption for laptops, but it is rather annoying for a desktop drive. I suppose a desktop can be single user, but I guess we have carefully buy "server" drives instead of "desktop" drives now. Just like you have to buy a "server" desktop to get ECC. While the WDC suggestions to tune logging and setting laptop_mode for linux (which they don't mention) can produce periods of inactivity for a single user long enough to be compatible with "IntelliPower", they are ineffective on a server with multiple virtual machines, or on a SAN server, with many clients, or even on a busy email server.

For laptop drives, power saving could be disabled on linux via "hdparm -B 255". This doesn't work for the new "green" desktop drives. The inactivity timer of this model seems to be set at 8 seconds, so I wrote a simple C program to read a sector from each drive every 8 seconds in O_DIRECT mode (to bypass caching). WDC provides a DOS utility to adjust the inactivity timer - setting a very high value effectively disables it. Unfortunately, these drives were in the field before I noticed the problem.

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"Green" drives fubar servers

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