Q: Should I use so called “Green” drives in a NAS system and what is WDIDLE?
A: The choice is up to you but we recommend you don't unless you really know what you are doing.
Western Digital's Caviar Green HDDs suffer from what some people may consider to be a critical design flaw caused by an aggressive power-saving feature. So do drives from other manufacturers, we don't mean to single WD out and only concentrate on them because they are one of the most popular brands with NAS4Free members.
Western Digital markets a technology called Intellipark (aka Idle 3 mode) and it is designed to reduce power consumption, in part by positioning the HDD's heads in a park position and turning off unnecessary electronics after 8 seconds of inactivity. Other manufacturers market similar technology under different names, if you are unsure about your drive, check the specifications on the manufacturers' web site!
According to XigmaNAS members experience, anecdotal evidence and other published reports, some software, operating systems and types of use ( particularly NAS environments ) are not recommended with Intellipark style features since they can cause endless head parking movement as the HDD continuously goes in/out of idle mode. This behavior creates stress on the HDD and that could lead to the following issues:
Western Digital posted a knowledge base article, where it claims that “The number of systems using such applications and utilities is limited”, a statement which makes little sense to NAS users/enthusiasts. Sending an HDD to idle mode only after 8 seconds of activity is normally not desirable behavior in a NAS system. Lots of software dislike this behavior as they are constantly writing and reading data to/from the HDD.
According to Western Digital, the following models are affected: WD20EADS, WD20EARS, WD15EADS, WD15EARS, WD10EADS, WD10EARS, WD8000AARS, WD7500AADS, WD7500AARS, WD6400AADS, WD6400AARS, WD5000AADS, WD5000AARS, WD1000FYPS, WD7500AYPS and WD7501AYPS.
In their defense, Daniel Mauerhofer, Head of EMEA PR in Western Digital is reported to have written the following in response to criticism from certain publications:
“What you have described as a “critical design flaw” in a recent article is rather a misuse of a drive, which was not designed for the referenced system type. In summary, this issue is far from critical, does not impair normal functionality or place data at risk, can be mitigated with a utility for the small percentage of systems affected, and is a well understood industry standard.
This design feature is designed for power savings in systems that can take advantage of the Idle 3 mode. With the heads parked in Idle 3 mode, a typical WD Caviar Green drive with 4 platters saves an additional 400mW of power, which is roughly 10% of the power consumed in Idle 2 mode. This has been a standard feature of modern notebook drives.
Many OS’s, including Windows, have been modified to take advantage of this power savings mode (which has been standardized by the T10 and T13 committees) by eliminating a sync operation that occurred every 30 to 60 seconds regardless of host or user inactivity.
The systems in which you are referencing that are reporting the issue has not been modified appropriately, and for these systems, the Idle 3 feature should be turned off.
The WD Caviar Green drives are not recommended for and are not warranted for use in RAID environments utilizing Enterprise HBAs and/or expanders, nor in multi-bay chassis, as they are not designed for, nor tested in, these specific types of RAID applications. For all Business Critical RAID applications, please consider WD’s Enterprise Hard Drives or for home/small business usage the WD's RED series Hard Drives, which are specifically designed with RAID-specific, time-limited error recovery (TLER), are tested extensively in 24×7 RAID applications, and include features like enhanced RAFF technology and thermal extended burn-in testing. The Idle 3 feature can be disabled for those systems that are unable to take advantage of this power savings mode. WD has always provided applications engineering assistance to system integrators to maximize system performance while also minimizing the amount of power consumed by our hard drives.”
Western Digital has released a DOS-based utility to modify the behavior of the HDD to wait longer before invoking idle mode. However, since most of their latest HDDs still ship with the default setting of 8 seconds, we strongly recommend users with affected HDDs to use the utility and monitor S.M.A.R.T data immediately. Other manufacturers may have similar utilities which you are encouraged to explore for non-WD drives.
How to Adjust Intellipark's Timer
We appreciate drive manufacturer's efforts to conserve energy and protect the environment, but features like Intellipark are less important than ensuring your data do not commit suicide! After all, is a clean environment without your data really worth living in?
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