Hi,

 

I am building my first unraid box. Due to the flooding in Thailand, the cheapest 2TB drives I could find lately were two external drives. I wanted to run them through a preclear before I opened them up so I wouldn't bork the warranty.

 

They are both running at the same time through usb 2.0. Although pretty slow at 19MB/s each, it is fine as I am not in a rush. (One preclear cycle will take 3.5 days)

 

The only problem is that SMART is currently not working. When I started it, it warned me that SMART was not going to work, but typing "Yes" still started the process. Is the preclear still going to work even without the active SMART reporting??

 

Thanks.

Yes. Is should work but you won't know if any sectors are bad. It will still write and read back the the entire disk. It's better than nothing.

Hmm.

 

So basically doing this is not really going to tell me if the hdd is reliable or not? When I open it up, connect it through sata and run the preclear again, it might find a ton of errors?

 

I better try to open it without voiding the warranty. I'll bust out my hairdryer :-)

Hmm.

 

So basically doing this is not really going to tell me if the hdd is reliable or not? When I open it up, connect it through sata and run the preclear again, it might find a ton of errors?

 

I better try to open it without voiding the warranty. I'll bust out my hairdryer :-)

The preclear will still work, the SMART parameters on the disk will be set and un-readable sectors still set as pending re-allocation/realloacted, but you may not be able the smart report until after the disk is removed from the USB housing and connected to a disk controller directly.

 

Make sure you are using the latest version of the preclear script. 

 

After the preclear is completed, and before you remove it from the external case, try a manual smart report and see if it works.

 

smartctl -a /dev/sdX

 

Regardless, there is no need to run another full preclear when you can look at a smart status report after it is done.

 

Joe L.

 

Joe L.

 

Oh ok. I will definitely try a manual smart report when it is done.

 

And when you say another preclear is not needed, is one cycle really enough to determine the reliability of a new drive?

Because on these boards I have been reading about people recommending three cycles, but I'm not sure if it's overkill or not.

 

Thanks

And when you say another preclear is not needed, is one cycle really enough to determine the reliability of a new drive?

Because on these boards I have been reading about people recommending three cycles, but I'm not sure if it's overkill or not.

 

Thanks

The number of cycles to run is entirely up to you.  I run multiple.  Some only run one.  Others run none.

If the first cycle shows no change in re-allocated sectors, and a second does not, then I'd skip a third if pressed for time, but do it if not.

 

Joe L.

Oh ok. I will definitely try a manual smart report when it is done.

 

And when you say another preclear is not needed, is one cycle really enough to determine the reliability of a new drive?

Because on these boards I have been reading about people recommending three cycles, but I'm not sure if it's overkill or not.

 

Thanks

 

If its a drive I've been using for awhile in another system without issues - I run 1 full cycle (sometimes on the larger drives skip the pre-read).

 

If its a drive I'm not sure of, or a new one, I do at least 2 full cycles, perhaps 3 if its going to be my current spare so that I know its ready to take the place of a failing (should that happen).

Thanks for the help guys,

 

These are brand new drives and I will do 3 full cycles. However, through usb 2.0, one full cycle is taking about 115 hours (close to 5 days) for both drives at the same time. I would like to cut that time down as much as I can :-)

 

Per Joe L.'s suggestion, I will try "smartctl -a /dev/sdX" at the end of this first cycle (should be over by this afternoon, currently at 92%). But if that does not work, what options do I have in determining whether the drive is bad or not without opening the case?

 

Is SMART data still generated and stored on the drive regarding any errors during the preclear process? Can I hook it up to another machine afterwards, maybe win7, and try to read that SMART data there?

 

Thanks

Ok, the preclear is finally over and I tried the "smartctl -a /dev/sdX" and got the following response

 

smartctl 5.39.1 2010-01-28 r3054 [i486-slackware-linux-gnu] (local build)
Copyright (C) 2002-10 by Bruce Allen, http://smartmontools.sourceforge.net

/dev/sdc: Unknown USB bridge [0x0bc2:0x50a1 (0x100)]
Smartctl: please specify device type with the -d option.

Use smartctl -h to get a usage summary

 

 

For one of the drives, the option "-d sat -t long" seemed to work (it will take some time to finish, if it ever does)

But for the other one, whatever -d or -t option I tried resulted in an error.

 

Any help would be appreciated.

 

Thanks

 

PS. How do you guys deal with this issue where you're trying to test an external drive that will be added to the array without voiding the warranty before preclear?

UPDATE:

 

The one drive did the "-d sat -t short" and no errors reported

 

The other drive finally accepted "-d sat,12 -t short" completed without error

 

Now the golden question is, does that mean the preclear was successful with no errors reported???

 

Thanks

 

 

EDIT: Nevermind, I forgot to use the -a option,  when I used that, it told me no smart errors were reported. I am going to go ahead and dissect the casings and run two more cycles through SATA.

 

Thanks everyone for your help.