Western Digital WD20EURS

[Sebastian]

Hi all,

i did a search for the "lowest-power" 2tb drive at my preffered webshop and found the WD20EURS. I can not find any usefull reports/tests for this drive, does anyone in this forum have experiance with this drive? Do you think its "ok" for an simple whs? What low power drive would you suggest?

kind regards
sebastian

 

[Patrick]

The WD20EURS is a AV-GP drive. Those are generally meant to just have tons of sequential writes with some reads because they are primarily for storing things like security camera footage. The big difference between this and EARS drives is that the WD20EURS does not try to correct errors like the EARS drives as that hurts sequential read/write performance. It is generally recommended that one does not use WD20EURS for more random I/O storage.

Personally, I would look into the Samsung's, WD EARS, or maybe the Hitachi green drives.

 

[john4200]

What do you mean by "does not try to correct errors" and do you have a reference on that?

If you compare the spec sheet values for Non-recoverable read errors per bits read for the WD20EURS and the WD20EARS, they are both <1 in 10^14.

http://www.wdc.com/wdproducts/library/SpecSheet/ENG/2879-701250.pdf

http://www.wdc.com/wdproducts/library/SpecSheet/ENG/2879-701229.pdf

Also, it is not on the spec sheet, but I think there is little, if any, difference in seek performance of the drives. The only significant difference that I can see from WD specifications is that the AV-GP products implement "preemptive wear leveling": "The drive arm frequently sweeps across the disk to reduce uneven wear on the drive surface". Now, that obviously would slow down transfer rate slightly, but my guess is that it is barely perceptible.

The spec sheet values for the EARS seems to refer to the 4-platter version, while the EURS seems to be a 3-platter version. I suspect the EURS only comes in the 3-platter version, while the EARS can come in either 3- or 4-platter version, and it is difficult to tell which you will get until you actually have the drive.

It also looks like the EARS has a lower-power idle mode than the EURS. Maybe the EURS never completely idles because of the wear leveling?

 

[Patrick]

So the big difference is the use on the AV-GP of the ATA/ATAPI-7 streaming commands which give you things like shorter error recovery time limits and continuous stream commands that will ignore errors to keep the stream going. Off the top of my head it is like 4.17.1 or 4.17.2 that talks about the streaming commands (could be totally wrong though). In a lot of applications you would bias towards error recovery versus a constant stream. This is the stuff that is really good for recording and playing back video, but is not the most data-secure way to go about it.

Physically though, I think they are the same drives.

 

[odditory]

For low power get yourself an Hitachi 5K3000 2TB drive and be done with it, especially if you're talking WHS.

Forget WD, especially if there's a chance you might ever place the drives in a striped array (hardware raid or zfs).

 

[Sebastian]

Thanks

Thanks for your feedback, i think i will wait till Hitachi 5K3000 Drives are available in Germany...

 

[cbhattarai]

I would suggest you for the lowest-power" 2tb drive that is Seagate Barracuda LP ST32000542AS 2TB