Discussion in 'Reviews & Articles' started by Adrian Wong, Feb 25, 2010.
Any news from WD?
I spoke to the WD rep last week. He forgot to ask them...
I'll chase him on Monday.
As somebody who worked for Hitachi for 7 years, I need to inject a bit of common sense in here if you don't mind.
The "guaranteed response time" on the AV drive is ONLY in play if the specific streaming instructions are used. Typically these instructions are only found in highly sophisticated surveillance systems where the software is aware that frames may have been dropped during unusually high write activities where multiple cameras had to be serviced at the same time. At no time is "corrupted data" written to a platter. The buffer fill is simply incomplete and then written as it is with full parity intact.
For normal Desktop use these instructions will never be in play. If you think about this, what some commentators are writing is ludicrous. If it ever was possible for a disk to write corrupted data the file system would be completely stuffed in milliseconds!
These disks are perfect for HTPC use because they are absolutely silent and great at continuous reads (notice I didn't say streaming here).
Does this make sense?
It does make sense, but we just wanted to be sure, which is why I've e-mailed WD about this several times. Unfortunately, they still have not replied.
That said, the point about data corruption isn't accurate. No one is insinuating that data written to the drive gets corrupted on the drive itself. What you wrote is absolutely correct. In the case of a CCTV system, if the load is excessive, then only part of the frame may be written to the drive but the frame would be written correctly, albeit missing some data, or some frames may be skipped.
I think our only concern would be that the time-out might possibly apply in a non-CCTV situation. If a bunch of files are copied from one drive to another under heavy load and if the time-out causes a file to be written to the drive with some data missing, then that file would be corrupt. Of course, logically, streaming commands should not affect normal transfers but we want to be sure.
The only write that can potentially "time out" is one that is written using a "streaming write" instruction. The programmer that issued that "special" instruction would know the implications (and benefits) of doing so. There is no risk of normal writes being effected.
Any news from WD? I just got an WD20EURS drive for Christmas.
I searched the WD community forum and found the following quotes from WD Staff oxter (regarding AV drives):
WD does not recommend this drive for RAID setups, this drives are mostly recommended for PVR/DVR, DVR recorders, and surveillance video recorders. They can be used in desktop computers, but the TLER is not needed if you are not running a RAID array.
These drives are best used for multimedia, it would be a good drive to hold your personal files, but I would not use it on a RAID (Hardware or Software based) if I were you.
Ignoring that, yes, it can be used just like any other consumer-level drive.
Here's the forum thread: http://community.wdc.com/t5/Other-Internal-Drives/WD-EARS-vs-WD-EURS-drives/td-p/129316
And in another thread regarding RE3 drives in a non-RAID enviroment (also from oxter):
You can use a RE drive in a non RAID environment, it will not give you any issue, the TLER will not affect your drive performance, nor will it cause you any issue with your OS.
I have a RE4 drive, I'm not using a RAID, I have not encounter any issue what so ever.
Believe it or not, I've sent them reminders but nothing specific yet. But I would think that crhendo is correct.
RE drives can be used in any environment, whether it's RAID or not.
I got an answer form WD support to my questions.
1. Does TLER only affect things when ATA streaming commands are used or also with standard ATA commands (for example READ DMA)?
ANSWER: No as it's deactivated by default
2. Will TLER time affect anything when used in a desktop computer with Windows XP or Windows 7, etc?
3. When you (Western Digital) say it is best for streaming videos, PVR, etc. but also a good drive for storing personal files you mean it is equally good for personal files as a non-AV Caviar Green (EARS, EARX, etc) or it's just not much worse in terms of data integrity and error recovery (not regarding other performance differences) but has a higher chance of corrupted data, which is pretty bad when saving a 100 GB disk image to an AV-GP drive for backup purpose?
ANSWER: There should be no difference with data integrity
4. I want to use my WD20EURS as my only drive in my computer. Occasionally I will backup important files, but if they were written incorrectly to my drive then it does not help if I copy that incorrect data to a backup drive. Does it have a higher chance then for example with a desktop Caviar Green?
ANSWER: WD20EURS does not have higher or less chance then Caviar Green to write incorrectly the data as long as customer use it as it's designed for in an appropriate environment.
5. Do AV-GP drives go into deep recovery cycle when needed if used in a desktop with Windows XP, 7, 8, etc?
ANSWER: Yes except if TLR is enabled when the drive is in a raid array. HDD will only spend 7 seconds to attempt to recover to avoid dropping out from an array.
FANTASTIC! Beats asking the local WD rep. +rep!!
Thanks for the help, and I will write a correction on this.
I never receive any mail ....
Not you. I e-mailed Pau.
Next time cc him!
I actually met up with Patrick from WD the other day, and mentioned this. He told me to shoot him an e-mail with the details via Pau and I did. That's why I didn't CC mikegas. LOL!
Separate names with a comma.