16.09.2015 18:53, Alex wrote: [] >>> All four are WD30EFRX-68EUZN0. They're not the cheapest WD disks, but >>> they're also not the ones with the 5yr warranty. The last array I >>> built using disks with 5yr warranty exceeded their capacity before the >>> warranty expired. >> >> Umm, 1st google result showed this: >> http://community.wd.com/t5/Desktop-Mobile-Drives/New-WD30EFRX-Red-Drive-Idle3-Timer-Set-to-8-Seconds-High-LCC-in/td-p/648821/page/5 > > I was really just looking for general input on RAID5 vs RAID6, but > that is good information. I knew the drives weren't basic desktop > drives and would be generally suitable for building a software RAID > array. > > Are you familiar with the idle3 time? It appears the idle3-tools can > be used to disable the idle3 timer entirely, which would disable > parking the head at all, correct? An addition. From hdparm(8) manpage: -J Get/set the Western Digital (WD) Green Drive's "idle3" timeout value. This timeout controls how often the drive parks its heads and enters a low power consumption state. The factory default is eight (8) seconds, which is a very poor choice for use with Linux. Leaving it at the default will result in hun‐ dreds of thousands of head load/unload cycles in a very short period of time. The drive mechanism is only rated for 300,000 to 1,000,000 cycles, so leaving it at the default could result in premature failure, not to mention the performance impact of the drive often having to wake-up before doing routine I/O. WD supply a WDIDLE3.EXE DOS utility for tweaking this setting, and you should use that program instead of hdparm if at all pos‐ sible. The reverse-engineered implementation in hdparm is not as complete as the original official program, even though it does seem to work on at a least a few drives. A full power cycle is required for any change in setting to take effect, regardless of which program is used to tweak things. A setting of 30 seconds is recommended for Linux use. Permitted values are from 8 to 12 seconds, and from 30 to 300 seconds in 30-second increments. Specify a value of zero (0) to disable the WD idle3 timer completely (NOT RECOMMENDED!). Thanks, /mjt -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
