I knew that hard disks had a limited time-life park/unpark-wise, but I didn’t know that was that bad. I always thought that because of ext3′s commit every 5 seconds, disk would never spin out and park the head. I was wrong. It seems that whether or not the disk is accessed, every put here the time it is for your disk minutes, it does park and unpark the head. Well, at least on laptop disks, because it seems this is not the case for desktops.
My 3 year-old vaio, which is now this web server, has a Load_Cycle_Count of 580465 for 9775 Power_On_Hours, which is about 1 load cycle per minute.
My 1 year-old vaio, has a Load_Cycle_Count of 83718 for 4043 Power_On_Hours, which is about 1 load cycle every 3 minutes.
While I managed to actually stop the load cycles to occur on the older vaio, with
hdparm -B254, nothing actually stopped it on the newer one. I tried to change some other parameters with
hdparm -S but nothing did work. I still have to take a look at the BIOS, though.
Now, the question is : why the fuck are the heads parked/unparked every little while even when accesses occur ? Is it a conspiracy so that laptop disks won’t last forever ?
Well, at least, I’ve never experienced a hard disk failure in 12 years of using computers with hard disks. For how long ?…
[Note: the Dell laptop provided by my company, running Windows XP (which also has a somewhat journalled filesystem and commits the journal every few seconds) has around 24000 load cycles for about 800 hours of use, which is 1 load cycle every 2 minutes, so this is not a Linux issue.]
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