What hard drives to choose ?

[Cooledspirit]

Hello,

I'd like to set up a FreeNas Z-Raid configuration. I have trouble selecting the hard drives (brand and type). I've read some threads on hard drives used and mostly the discussions are concerning WD's Green drives (I don't know if that's actually a good thing). I also know WD now has Red drives, that are advertised to be better compliant with NAS. I couldn't find much about other drives (maybe I looked in the wrong places).

• The WD Green drives are cheap but have an aggressive park head time. They park already after 8 seconds of idle time. You can't disable APM for this drive as APM is not supported by this drive, so you need to use a tool called WDIdle3 (a DOS tool) BEFORE you build them in. I also heard that WDIdle3 might not work for all Green drives and that some people even have reported lower perfomance after an update performed by that tool on WD Green drives (don't ask me to confirm, this is just what I read on other places and threads). If WDIdle3 works, you can set it to 5 minutes instead of 8 seconds. These drives have 2 years warranty.
• The WD Red drives are more robust (better dealing with vibration and better MTBF), consume even less energy than the Green Drives and have numerous options, for example setting TLER and options involving parking the head and setting idle time. By default the option to park the heads is completely turned off, this is usefull for systems running 24/7. You again need this WDIdle3 tool to change this (although not listed by WD on the tools page for that type of drives). These drives don't have APM support either. Not to mention, these drives are more expensive. These drives have 3 years warranty.

Here come my questions:

1. I read that for software raid, TLER is not relevant. Is that true ?
2. I don't want my system to run 24/7, I want it to go into suspend mode (suspend to RAM preferably) when no activity happens after like 30 minutes. Suppose I would use the Red Drive and I want my system to go into suspend mode, I assume this means I need to enable parking of heads for the Red Drive?
3. How does FreeNas manage energy? Meaning that the system goes in some sort of low energy consumption state and remain standby (I phrase it like this, because I don't know if suspend to ram can be configured like this for FreeNas or what possible alternatives are better).
4. Are there decent hard drives (brand is not relevant) that simply have full support (APM yes/no) from FreeNas and don't require extra (DOS) tools but are simply fully managed by FreeNas (park heads, spin up, idle time, ....) ? By decent I mean: reliable in terms of life span, reasonable energy consumption, acceptable performance. I would take the WD Green or Red drive as reference for price, energy consumption and performance.

Many thanks in advance for your valuable input!

Regards,

Cooled Spirit.

 

[fracai]

Selecting drives is mystly mysticism and superstition. I can't really help you there, but I can say that I ran wdidle3 (actually idl3-tools) on a drive AFTER starting to use it with FreeNAS (I somehow missed this drive during prep) and I haven't noticed any change in performance.

 

[jgreco]

1) TLER is relevant in any environment where you would prefer the system to continue to be responsive (possibly by reporting a bad sector instead of retrying a bunch of times and eventually fetching the data). Some hardware RAID controllers freak out if a drive is responding slowly and will mark the drive as bad, which is the source of that urban myth. Truth is, TLER can be just as important on software RAID if you are serving protocols that involve timeouts and hanging clients that cannot be inconvenienced in that manner.

2) The hard drives will handle suspended mode all on their own, if you actually go that route.

3) Modern UNIX systems can lower their clock speed and optimize for low workloads, but this is not the same as suspending/standby/etc. Configuring the hard drives to sleep during long idle periods will result in significant power savings. Making sure you're not throwing needless work at the NAS will help too. Designing a system from the ground-up to be energy efficient is tricky. You start at the power supply, consider the right fans and other chassis loads, select the right motherboard, CPU, memory, avoid adding unnecessary controllers, check out the hard drive power consumption, etc.

4) No, because drive manufacturers don't work that way. You can get yourself some WD drives, twiddle them appropriately, then never need to think about it again. As close as you'll get.

 

[cyberjock]

I have 22 WD green drives. You can change the head park time with wdidle anytime, even after you've created a zpool. You just have to boot up from a DOS disk to execute the command. I changed it to 5 mins and I've had no problems for the 3 years I've owned my drives.

 

[tingo]

Didn't someone make a script (which works in FreeBSD) to replace the wdidle utility? I can't seem to find it now.

 

[Cooledspirit]

Good to know !

1) TLER is relevant in any environment where you would prefer the system to continue to be responsive (possibly by reporting a bad sector instead of retrying a bunch of times and eventually fetching the data). Some hardware RAID controllers freak out if a drive is responding slowly and will mark the drive as bad, which is the source of that urban myth. Truth is, TLER can be just as important on software RAID if you are serving protocols that involve timeouts and hanging clients that cannot be inconvenienced in that manner. ==> this means to me that the RED series is actually a good choice and that FreeNas will handle them just fine, provided they are configured properly.
2) The hard drives will handle suspended mode all on their own, if you actually go that route. ==> OK, that is good to know, but will I need to enable the head parking for the red drives (as it is by default disabled) ? Won't the heads just land on the disk surface otherwise ?
3) Modern UNIX systems can lower their clock speed and optimize for low workloads, but this is not the same as suspending/standby/etc. Configuring the hard drives to sleep during long idle periods will result in significant power savings. Making sure you're not throwing needless work at the NAS will help too. Designing a system from the ground-up to be energy efficient is tricky. You start at the power supply, consider the right fans and other chassis loads, select the right motherboard, CPU, memory, avoid adding unnecessary controllers, check out the hard drive power consumption, etc. ==> you sound like you have something running this way ? Either way, any proposal for 6 to 8 sata drives is highly appreciated ;) !
4) No, because drive manufacturers don't work that way. You can get yourself some WD drives, twiddle them appropriately, then never need to think about it again. As close as you'll get. ==> Pffffffff! I want to believe in Santa !!!! :)

Good to know, many thanks !
I can let you know what configuration I had in mind if you feel up to it!

Many thanks,

Cooled Spirit

 

[Cooledspirit]

@NoobSauce80: Great ! So no need to go for the extra expensive Red Series !

You don't have issues with TLER then ? Or is this something you set via WDIdle3 tool as well ?

Should you have any of the WD 3Tb Green drives, which model exactly do you have ? I'll try to buy the same model to make sure I don't run into trouble.
Please also mention your 2 Tb model ?

 

[Cooledspirit]

@Tingo: are you referring to the idle3 tools that Fracai mentionned earlier ? (http://idle3-tools.sourceforge.net/) Or something else ?

 

[Cooledspirit]

@Fracai: Many thanks. It says "experimental" ... but you seem to have had no issues ? Launched from within FreeBSD or do you have to move the drive to another PC (outside your raid) ?

 

[cyberjock]

@NoobSauce80: Great ! So no need to go for the extra expensive Red Series !

You don't have issues with TLER then ? Or is this something you set via WDIdle3 tool as well ?

Should you have any of the WD 3Tb Green drives, which model exactly do you have ? I'll try to buy the same model to make sure I don't run into trouble.
Please also mention your 2 Tb model ?

My drives are WD30EZRX and WD20EARS. I wouldn't use the FreeBSD tool just because its experimental. You only have to set this setting once, so it's not something you will have to do regularly. Just take the time to use the DOS disk and be done with it. No point in trying to reinvent the wheel and use an experimental tool that might not even work.

I have not had issues with TLER myself. TLER can ONLY be set with the ultra-expensive enterprise grade hard drives.

The heads normally touch the media when the drive is off. When the drive spins up a small cushion of air forms on the platter that the head actually rides on. The gap between the head and platter "head gap" is 2-4 nanometers. When a hard drive loses power the head is immediately pushed to what is called a landing zone and locked. As the drive spins down and the cushion of air goes away the head touches the platter again. The landing zone does not have any data, therefore no data can be damaged by the head rubbing the media. The head does take a very small amount of wear but is minimal since both surfaces are very very smooth.

WD has enhanced the head parking technology by moving the landing zone from a location on the platters to a mechanical arm next to the platters. The theory is that this does two things: the head shouldn't ever touch the media(extending the life of the head) and if you park the head regularly then you lower the air resistance inside the hard drive and power consumption goes down. Green drives aggressively park the heads(8 seconds) to save power. If you look around I posted a picture of the internals of a WD drive with the arm shown in the forums somewhere. Big picture though, heads don't typically wear out so you may not be directly extending the life of hard drives(there's lots more to do with wear products inside the drive, but I won't go into that here). The air resistance is a big plus because temperature has been found to be a larger factor in hard drive life than was previously believed. See the Google hard drive white paper for some good details. The documents the disk industry has are all internal and never been formally released :(.

All hard drives made in the last 20 years(at the least.. although I've heard it's been around since hard drives were platters) automatically "park" their heads on loss of power. You cannot change this, nor would you want to.

 

[joeschmuck]

@NoobSauce80: Great ! So no need to go for the extra expensive Red Series !

The extra expensive red series? I'm sure you are joking. $120 for a 2TB, same as practically all other desktop 2TB drives. NewEgg sells them for more but look at Amazon or Tiger Direct.

 

[Stephens]

I get can 2TB's for $100 pretty regularly now and they've even dipped to $90. The question is, are the additional features worth $20/drive? If I were buying today, I'd strongly consider the Reds.

I haven't tested them myself, but according to all I've read, the WD Red's DO support TLER.
http://www.pcper.com/news/Storage/WD-Red-drives-do-support-TLER
http://www.wd.com/en/products/products.aspx?id=810

With built in intelligent error recovery controls, NASware also prevents hard drives from being dropped off the RAID due to extended error recovery. This provides more availability and less down time rebuilding the RAID.

 

[Cooledspirit]

22 drives...

I have 22 WD green drives. You can change the head park time with wdidle anytime, even after you've created a zpool. You just have to boot up from a DOS disk to execute the command. I changed it to 5 mins and I've had no problems for the 3 years I've owned my drives.

That's a lot of drives (22 ==> lotsa TerraBytes) ... in what cases do you store all these ? Like 3 separate PC cases with each approx 8 disks ?

 

[Cooledspirit]

My drives are WD30EZRX and WD20EARS. I wouldn't use the FreeBSD tool just because its experimental. You only have to set this setting once, so it's not something you will have to do regularly. Just take the time to use the DOS disk and be done with it. No point in trying to reinvent the wheel and use an experimental tool that might not even work.

I have not had issues with TLER myself. TLER can ONLY be set with the ultra-expensive enterprise grade hard drives.

Here's a little background on head parking since you seem to be asking questions that indicate you don't have a good grasp of the fundamentals:

The heads normally touch the media when the drive is off. When the drive spins up a small cushion of air forms on the platter that the head actually rides on. The gap between the head and platter "head gap" is 2-4 nanometers. When a hard drive loses power the head is immediately pushed to what is called a landing zone and locked. As the drive spins down and the cushion of air goes away the head touches the platter again. The landing zone does not have any data, therefore no data can be damaged by the head rubbing the media. The head does take a very small amount of wear but is minimal since both surfaces are very very smooth.

WD has enhanced the head parking technology by moving the landing zone from a location on the platters to a mechanical arm next to the platters. The theory is that this does two things: the head shouldn't ever touch the media(extending the life of the head) and if you park the head regularly then you lower the air resistance inside the hard drive and power consumption goes down. Green drives aggressively park the heads(8 seconds) to save power. If you look around I posted a picture of the internals of a WD drive with the arm shown in the forums somewhere. Big picture though, heads don't typically wear out so you may not be directly extending the life of hard drives(there's lots more to do with wear products inside the drive, but I won't go into that here). The air resistance is a big plus because temperature has been found to be a larger factor in hard drive life than was previously believed. See the Google hard drive white paper for some good details. The documents the disk industry has are all internal and never been formally released :(.

All hard drives made in the last 20 years(at the least.. although I've heard it's been around since hard drives were platters) automatically "park" their heads on loss of power. You cannot change this, nor would you want to.

Thank you for this elaborate explanation. Is my deduction correct then, that even with "head parking" turned off in the Red series, the heads will safely park once the drive is turned off or turned to sleep ?

 

[joeschmuck]

Head parking occurs for all hard drives when the spindle powers down, which is generally called Idle but sometimes called Sleep. Head parking can also occur on many drives after not being accessed for a determined amount of time in which the heads are parked yet the spindle is still running which reduces the head wearing of the platters. Some drives (mostly A/V) have built in head wearing firmware which will force the heads across the entire platter surface periodically to ensure even wear. I'm sure that was overkill for an answer.

 

[cyberjock]

Thank you for this elaborate explanation. Is my deduction correct then, that even with "head parking" turned off in the Red series, the heads will safely park once the drive is turned off or turned to sleep ?

I think you are still confused. The WD Green drives have their aggressive head parking technology called "intelli-park". I'm not sure if WD Red had the same technology. I couldn't find anything that says that they do, so I think they don't. So your question is not valid for WD Red. Keep in mind that the Red drives were designed for NASes. Greens were not. If you want to use a Green drive in a NAS, then you have to use the wdidle program to make the Green more "NAS-friendly".

So to try to answer your question, the heads will always park safely once the drive is off or put to sleep, as has all hard drives in the last 20+ years. This was answered in my previous post.

Head parking can also occur on many drives after not being accessed for a determined amount of time in which the heads are parked yet the spindle is still running which reduces the head wearing of the platters. Some drives (mostly A/V) have built in head wearing firmware which will force the heads across the entire platter surface periodically to ensure even wear.

Neither of those statements are true. The head does not "wear" the platters down when the drive is spinning. Moving the head over the platters is only used (aside from seeking data) for thermal compensation. The data actually moves when the drives are first turned on and allowed to warm up. The hard drive does agressive temperature compensation for the first hour, then every 30 minutes or so afterwards. But the only wear on the drive will be when the spindle is too slow to form a good air cushion. The head is locked when parked to prevent the head from moving in the "inside to outside" direction. If the spindle is not spinning at a minimal speed then the disks can be damaged by the head rubbing at a right angle to the data. The firmware should make sure that the head never moves until the spindle hits the "minimal" speed.

 

[Cooledspirit]

I think you are still confused. The WD Green drives have their aggressive head parking technology called "intelli-park". I'm not sure if WD Red had the same technology. I couldn't find anything that says that they do, so I think they don't. So your question is not valid for WD Red. Keep in mind that the Red drives were designed for NASes. Greens were not. If you want to use a Green drive in a NAS, then you have to use the wdidle program to make the Green more "NAS-friendly".

So to try to answer your question, the heads will always park safely once the drive is off or put to sleep, as has all hard drives in the last 20+ years. This was answered in my previous post.
.

Hello NoobSauce80,

There is some confusion indeed, and my confusion is related to whether or not your answer applies to the WD Red drive (I understand about the Green drives, no worries). To elaborate on what and why I'm doubting, I will refer to a review of the WD Red drives in Anandtech: http://www.anandtech.com/show/6157/...iew-are-nasoptimized-hdds-worth-the-premium/2

If you read the page on "WD Red Lineup: Differentiating Features", you'll read in the paragraph "power management features" (which mentions the WD Green) that "As the screenshot above shows, head parking is completely disabled by default. It is also possible to set the head parking time limit, and it is sticky through power cycles. For NAS applications, it is better to leave it in the default state of head parking being disabled."

So my confusion was: what is the impact of that "head parking" disabled ? I was afraid the hard drive would get damaged if the system was shut down if head parking were disabled (because they assume a 24/7 running system). As you patiently mentionned (thank you for that), the heads will always park safely. Which I interpret that this "head parking" disabled or enabled is about the same as one would be capable of enabling or disabling the "intellipark" feature rather than setting the idle time to 5 minutes for Green Drives.

I hope I made the confusion clear and I also hope that I understood correctly :)

Many thanks !

David.

 

[cyberjock]

I see why you are confused. I very very much doubt that head parking would be completely disabled. Data would be lost fairly quickly since most powerdowns would result in the head being in the same place on the hard disk because the shutdown sequence would be the same most of the time. I think the only thing they are saying is that the drive doesn't park its head when the drive is operating, which is exactly what a NAS drive would be expected to do, or the setting is not user configurable. I think it's taking a BIG leap to assume that the drive has all head parking disabled. Head parking was originally designed because reliability was too low as magnetic domains got smaller. Data would be obliterated fairly quickly if a disk head was allowed to regularly touch the data.

Keep in mind that WD Green drives are the only drives I know of where you can(or need to) control the head parking. For all other drives I'm familiar with there is no "option" to change when the head parks in the firmware. Even if you could disable head parking during IDLE or poweroff states, nothing is gained. The drive won't achieve READY status any faster. AFAIK WD owns the patent on their Intelli-Park design and hasn't sold it to anyone else. Standard drives that do not have the extra Intelli-Park arm where the head parks will not see any benefit whatsoever with parking the head while the drive is operating. There is no power savings and no "wear and tear" saved.

 

[joeschmuck]

@ Noobsauce,
We will have to agree to disagree. I know the Samsung 2TB drives I had been running has a mode for parking the heads while leaving the drive running, it's very obvious when you hear the heads loading. This is not Intelli-park and as far as I know the drive must be put into this lower power mode. And as for the wear leveling, I've read about that in the past quite a bit and I've never heard of it on a non-A/V drive but I won't state it doesn't exist on a non-A/V drive, and everything I've read. Here is an example:
http://www.wdc.com/wdproducts/library/AAG/ENG/2178-771127.pdf

Which states: Preemptive Wear Leveling (PWL)
The drive arm frequently sweeps across
the disk to reduce uneven wear on the
drive surface common to audio video
streaming applications.

I've never heard of the arm being moved for thermal stabilization benefits and I don't recall the heads on my computer drive just sweeping across the platters without some sort of cause. And the heads do crash periodically, it happens and with these mechanical drives there is no way around it. On some drives, like the newer laptop drives, a sudden impact forces them to park the heads immediately. The heads pop back out quickly after that event but it's an attempt to reduce the damage inflicted by the user.

@David,
I'm glad you are diving into the details of your parts before you purchase them but if you are going to build a NAS from scratch and buy new drives, I strongly suggest you buy the WD Red drive lineup. They are new but they are also a NAS certified drive, meaning they can handle 24/7 abuse. They are also low power and very quiet. The cost is the same as a good quality desktop drive as well.

I have just tested the drives using ataidle command "atailde -S 30 /dev/ada0" to verify the drives can be commanded to sleep, used the "smartctl -A /dev/ada0" to check the spinup count before and after and it increments. I also used the -n standby switch and it recognized the drive was in standby. I have setup my FreeNAS settings to sleep after 30 minutes and when I get home tonight I'll know if they went to sleep on their own. Current spinup count is 17 for my ada0 drive. If it changes then the drives must have spun down.

I'm not sure what else you need to know.

 

[fracai]

@Fracai: Many thanks. It says "experimental" ... but you seem to have had no issues ? Launched from within FreeBSD or do you have to move the drive to another PC (outside your raid) ?

I ran it under Ubuntu, with the drives connected using this (it even supported smartmontools using '-d sat'). And the setting doesn't take until you power cycle the drive, so it isn't much extra headache to remove the drive.

It would have been nice to have compiled it for FreeNAS, but for the number of times I'll need to do this, it wasn't worth it. I had to connect the drives to the Ubuntu system anyway in order to shuffle my data around.