is it true that bundling sata cables together will cause interference and data loss?

 

also, is it safe to use caviar black drives for unraid? i heard that they are not meant to be used in raid systems

 

thank you

Somewhere within the discussion forums we've covered the use of consumer level drives in unRAID. Since unRAID is NOT your typical RAID, consumer level drives are safe to use.

 

Most RAID controllers will only wait a short time for a drive to respond.  Usually this period is as short as 10-20 seconds.  If the drive hits this time limit, the controller will mark the entire drive as failed.  This is not something you want to happen routinely, as your entire array is at jeopardy of going offline.  The preferred behavior in RAID environments is for the drive to quickly time-out and report the sector as bad, so that the raid controller can reconstruct the missing data from the parity information stored on the other drives in the array.

 

So what’s the real difference between the consumer models and the “RAID Edition” drives from Western Digital?  They have the same vital specs.  They are even rumored to come off the same assembly line as the “Black” edition consumer grade drives.  The chief difference, apart from a 60%-80% difference in price, comes down to a firmware setting.  (source) The setting prevents the drive from spending too much time attempting to recover data from a sector on disk.   This feature is called Time Limited Error Recover (TLER.)  It’s turned off by default on the WD Black, and it’s turned on by default on the RE3.  And guess what?  You can change the defaults with a simple command line utility, WDTLER.EXE.  Wikipedia has an article on how to make the change. TLER

 

Time-Limited Error Recovery (TLER) is a name used by Western Digital for a hard drive feature that allows improved error handling in a RAID  environment. In some cases, there is a conflict as to whether error handling should be undertaken by the hard drive or by the RAID controller, which leads to drives being marked as unusable and significant performance degradation, when this could otherwise have been avoided. Similar technologies are called Error Recovery Control (ERC), used by competitor Seagate, and Command Completion Time Limit (CCTL), used by Samsung and Hitachi.

 

It is best for TLER to be "Enabled" when in a RAID array to prevent the recovery time from a disk read or write error from exceeding the RAID controller's timeout threshold. If a drive times out, the hard disk will need to be manually re-added to the array, requiring a re-build and re-synchronization of the hard disk. TLER seeks to prevent this by interrupting error correction before timeout, to report failures only for data segments. The result is increased reliability in a RAID array.

 

 

is it true that bundling sata cables together will cause interference and data loss?

It should not if they are of high quality and self-shielded.  It all depends on how much noise there is in the lines they are bundled with.

also, is it safe to use caviar black drives for unraid? i heard that they are not meant to be used in raid systems

This seems to be the root article that discourages their use in a RAID-0. (one of the initial reviews)  The performance for ALL drives seems lower in RAID-0 than in stand alone mode, so I'd not worry about it in the least bit.  You want the high rotational speed, and they should work well in an unRAID array.

 

Joe L.

great, thanks guys

i was going to start another thread but the title of this one is perfect so i dont want to get yelled at...lol

 

i cant seem to find a good quality sata cable thats short im talking like 3 inches in that area. and would like sata 3 if possible. i just pulled out a 2.5" sata from a machine today. so obviously they are made ive found a 9 inch but that was attatched to a 4pin power cable as well and i just need the sata...thanks!

I just scored some 7" orange SATA cables from eBay.

Didn't see any as short as 3", but if they are made, they might be out there.