Preclear and Failed Drives

[DoeBoye]

Well folks, Here's that poll I was suggesting. I'm very curious to see the results! And for those of you who aren't running preclear.... What's Wrong With You!!???  .

I voted for 1 cycle with failed drives.

[prostuff1]

Well folks, Here's that poll I was suggesting. I'm very curious to see the results! And for those of you who aren't running preclear.... What's Wrong With You!!???  .

I voted for 1 cycle with failed drives.

I run 3 cycles, and have had drives fail on the second or third cycle.  I ran a drive with one pass and it was good, I put it into service in my array and then it failed about 2 weeks later.  That is the main reason I run 3 cycles.  I have had a couple of drives preclear on the first cycle OK (not perfect) only to show worse signs on the second and third preclear.

[Rajahal]

I didn't see the option I wanted, so I edited the poll and added it.  I always run preclear for a minimum of 2 cycles on every drive I use, but I've only ever see a drive fail on the first cycle if it fails at all.  When a drive fails on the first cycle it typically fails on all subsequent cycles as well.

I have also seen a few drives that took exceedingly long on the first cycle (like 2x or longer than normal), but still passed, then ran at normal speed on all subsequent cycles.  These drives have all turned out to be fine in normal use.  I can't explain why the first pass took so long.

[bjp999]

Suggested options ...

- What's preclear
- Ive had a drive fail after 1 or more preclear cycles (please post your experience)
- I've had a drive fail in the first cycle of preclear
- I've had a drive fail in the second cycle of preclear
- I've had a drive fail in the third or higher cycle of preclear
- I routinely run 1 preclear cycle and never had a drive fail during preclear
- I routinely run 2 preclear cycles and never had a drive fail during preclear
- I routinely run 3 or more preclear cycles and never had a drive fail during preclear

[WeeboTech]

Well folks, Here's that poll I was suggesting. I'm very curious to see the results! And for those of you who aren't running preclear.... What's Wrong With You!!???  .

I voted for 1 cycle with failed drives.

I run 3 cycles, and have had drives fail on the second or third cycle.  I ran a drive with one pass and it was good, I put it into service in my array and then it failed about 2 weeks later.  That is the main reason I run 3 cycles.  I have had a couple of drives preclear on the first cycle OK (not perfect) only to show worse signs on the second and third preclear.

I'm dealing with my first failed drive and this is what I've seen. 1 successful preclear, then during the rebuild I had all sorts of failures. Think I'm gonna run a few preclears on another spare drive I have.. phew good thing I keep a few around.

[vca]

I have also seen a few drives that took exceedingly long on the first cycle (like 2x or longer than normal), but still passed, then ran at normal speed on all subsequent cycles.  These drives have all turned out to be fine in normal use.  I can't explain why the first pass took so long.

I've had one drive that was slow on the first preclear pass (it took about twice as long as normal) and was just as slow on the second pass, so I took it back to the dealer and got a replacement.

Stephen

[Joe L.]

In my case a brand new Seagate 2TB ST32000542AS drive passed the first preclear, but with some sectors re-allocated.
The second preclear it re-allocated LOTS of sectors, started making LOTS of funny noises, and failed completely.

[Superorb]

In my case a brand new Seagate 2TB ST32000542AS drive passed the first preclear, but with some sectors re-allocated.
The second preclear it re-allocated LOTS of sectors, started making LOTS of funny noises, and failed completely.

Lesson learned. On my new drive I just got I'm going to do 3 clears instead of the single clears I did on my older drives that have been in service for months.

[DoeBoye]

For the record, I voted as a one time pre-clear, but I've since started pre-clearing 3 times because of this thread! It helps to buy drives well ahead of when they are actually needed

DB.

[KYThrill]

This poll reminds me of my Hitachi 7k2000 parity drive that passed two pre-clears, was in service 6 months, threw 5-10 errors, smart reported showed reallocated sectors, swapped in a spare drive, pre-cleared the erroring drive about 10-11 times.  It failed all but the last two, but did pass the final two pre-clear attempts.  I put it back into service as a data drive and it has been working perfectly for several months.

So I guess I don't see my choice.  I preclear until the drive can pass two consecutive pre-clears, or until it reaches a failure criteria that would let me RMA it.  Even though my Hitachi was failing one pre-clear after another, it would still pass the stupid Hitachi drive analysis test, so it wasn't eligible for RMA.  So I was going to preclear that drive until it fried if that is what it took.

[opentoe]

I'll take a long data re-build a good clear for me. If the drive is going to fail right away, it will during a re-build. A drive can fail at any given time.

[Rajahal]

I'll take a long data re-build a good clear for me. If the drive is going to fail right away, it will during a re-build. A drive can fail at any given time.

I don't think that is true.  A data rebuild will write to the entire drive, so that's good.  But it won't read from it.  A data rebuild followed by a parity check would be better in my opinion, but still not as good as a full preclear (which is a read, then a write, then a read again).  The preclear also tests both sequential and random writes/reads, whereas the data rebuild + parity check would only test sequential writes/reads.

[madburg]

Great post/poll. I will not vote just yet...

I started my unRAID & preclear_disk experience as followed. I precleared many old drives which I will use at the end of my 24 drive unit. Once I exceed all available slot with 2TB drives I will then swap out my older drives. Squeezing my money worth for what I paid for these puppy's back in the day. (P.S. all Hitachi 7200k drives. 160Gb, 250Gb, 320Gb)

I was preclearing these old drives with 3 Passes, only one drive showed reallocated sectors from a very lond time ago and no new additions. So I thought this was the recommended. I then started purchasing my new Hitachi 2TB, first was a 7200k for parity and precleared it with three passes all was well, the second Hitachi was a 2Tb green drive, also 3 passes. All these drives were done in an old foxconn MB. When I moved them to my new supermicro MB with SAS controllers, i decided to run one more pass on each, I was not aware of the -D option in preclear and ended up with now SMART data in the reports... So I ended up running another pass on each with the -D option to get the SMART data in the reports. ALL still came up fine. Then I read a post here in the forums about what does 1 preclear pass equate to for a harddrive lifespan (workload)... i think most of us were surprised by Joe L.'s anwser. So my next (2)2TB Hitachi green drives I only ran 2 passes on and all is still well. I am waiting on 4 more 2TB Hitachi's and plain to do the same 2 FULL passes on each, if I see anything out side of 0,0,0,0's then I will apply more passes. And then I will vote in this poll.

Thank you for the great script Joe L., great post/poll guys! and love the forum as well as the maturing product unRAID! rocks.

[BRiT]

Somehow I never noticed this thread until now.

I run 3 or more preclear cycles on my drives and I've seen drives pass the first cycle but failed hard in the second cycle. The third cycle confirmed that the drives were toast. It even failed the smart short test with read failures!

[0bit]

Hello all

I guess this is good as any for a first post.  I precleared 20 2tb drives and a 500gb cache drive 3 cycles each and there were no errors.