[SOLVED] Advice for a N00b

[dgaschk]

Pre-clear does not write sequentially. The write algorithm causes the drive head to constantly move, searching from inner to outer cylinders and back.  It is a very good workout for the drive. It also does a pre-read and a post-read that will reveal any pending, reallocated, or unreadable sectors. The standard clear does a long sequential write. That is why it is so much faster. It does not verify what it has written. It assumes the disk is good. You will have no idea the disk is failing until it does.

[Joe L.]

Close, but not quite correct.

 

Pre-clear does not write read sequentially. The write read algorithm causes the drive head to constantly move, searching from inner to outer cylinders and back.  It is a very good workout for the drive. It also does a pre-read and a post-read that will reveal any pending, reallocated, or unreadable sectors. The standard clear only does a long sequential write. That is why it is so much faster. It does not verify what it has written. It assumes the disk is good. You will have no idea the disk is failing until it does. After you are unable to read back the data you have written.

 

[TODDLT]

Close, but not quite correct.

 

Pre-clear does not write read sequentially. The write read algorithm causes the drive head to constantly move, searching from inner to outer cylinders and back.  It is a very good workout for the drive. It also does a pre-read and a post-read that will reveal any pending, reallocated, or unreadable sectors. The standard clear only does a long sequential write. That is why it is so much faster. It does not verify what it has written. It assumes the disk is good. You will have no idea the disk is failing until it does. After you are unable to read back the data you have written.

 

 

Would this still be necessary on a drive that is 2/3 full and in use for a year?  If you guys really recommend it, I will do it, but don't want to add a day into the process if a years worth of use would provide a sufficient test. 

[Joe L.]

Close, but not quite correct.

 

Pre-clear does not write read sequentially. The write read algorithm causes the drive head to constantly move, searching from inner to outer cylinders and back.  It is a very good workout for the drive. It also does a pre-read and a post-read that will reveal any pending, reallocated, or unreadable sectors. The standard clear only does a long sequential write. That is why it is so much faster. It does not verify what it has written. It assumes the disk is good. You will have no idea the disk is failing until it does. After you are unable to read back the data you have written.

 

 

Would this still be necessary on a drive that is 2/3 full and in use for a year?

yes.

Realize, it will completely erase the drive, so do not do it on a drive whose contents you want to keep.

[TODDLT]

Would this still be necessary on a drive that is 2/3 full and in use for a year?

yes.

Realize, it will completely erase the drive, so do not do it on a drive whose contents you want to keep.

 

Understood.  That was my hesitancy.  If I could load up all my drives at once, and let it go for a day or so, not a big deal.  However, It will probably take at least 2 if not 3 cycles of clear / copy / clear / copy to get it all transfered. 

 

Oh well, worth it to do it right. 

[christuf]

Would this still be necessary on a drive that is 2/3 full and in use for a year?  If you guys really recommend it, I will do it, but don't want to add a day into the process if a years worth of use would provide a sufficient test. 

 

Two schools of thought here - one is that you've been trusting your data to a non-preclear tested drive for a year, so why test it now...

 

Second one is perhaps you've been lucky so far, and the best course of action is to "quit" while you're ahead.  Take the time to make sure the drive is reliable for the storage of your data while you're transferring to UnRAID.  I appreciate you want it to be up and running asap... I know I did, but a day spent now could save a lot of heartache later.

 

It's kind of like driving down a highway for an hour every day at 90mph.  There won't be a cop out there to catch you every day... perhaps not even for a month, but I guarantee that you're not going to manage a year without a ticket.

 

I can't take any credit for this quote, but I love it and think it is germane to this topic... "There are two types of hard drives: those that have failed already, and those that will fail in future"