August 20, 201312 yr I have 3, 3 TB drives. Even doing them simultaneously will take forever. It will probably be close to a week until 3 pre clears are done. Is this something that everyone does? My guess is yes because this is unRAID, and the people who use this are the ones who are concerned about data loss and have a set up a system that will assist in preventing this. Just curious!
August 20, 201312 yr I always preclear my drives. Saved me from installing 5 bad drives I have received from Newegg this year. It takes me about 54 hours to run 2 preclear cycles on my WD Red 3tb drives. I also run them one at a time but I have run multiples without an issue.
August 20, 201312 yr Author What constitutes a "bad" drive? Is this a drive that certainly would have gone down quickly, or a drive that did not pass all tests perfectly but could have very well been a viable drive?
August 20, 201312 yr I run preclear on all my mechanical drives because I'd rather have the drive fail before I put my data on it than have it fail later on after it is in the array. I suppose if you keep a spare drive available it lessens your risk some degree...as long as the spare lasts long enough to RMA the first. Parity only protects you from one lost hard drive at a time. The last 3TB I cleared took 24 hours which was a SATA III Toshiba on SATA III controller. I had a Seagate 3TB take 48 hours before. It ended up reporting a high fly write so I ran it again. 96 hours later and no change in smart report it was added to the array. Painful, but not as painful as replacing the lost data if a second drive goes down while piddle farting around with a new drive that failed shortly after installing it. Preclear will help shake out any mechanical or media problems that could cause it to fail sooner rather than later.
August 20, 201312 yr Of the bad drives I have had none of them even finished the preclear. 2 died during the post read. They just dropped to 0mb/s and stopped doing anything, then made lots of noise. The other 3 all were dead from the get go. One would not read at all and the other two couldn't complete the pre-read.
August 20, 201312 yr What constitutes a "bad" drive? Is this a drive that certainly would have gone down quickly, or a drive that did not pass all tests perfectly but could have very well been a viable drive? Anything that fails a preclear is a bad drive IMO. Usually the drives are not viable because the preclear will finish them off, however.. Even if it did make it out alive with some errors I'd send it back. Would you buy a new car if it was anything less then perfect? Big dent in the side would still a viable car, but I wouldn't buy it! Think of the preclear as taking a test drive... on a WRC rally stage... for 56 hours. 2 passes on every new drive now.. For unraid or not! Might as well catch them early before the fail the day after my warrantee is up.
August 21, 201312 yr Think of the preclear as taking a test drive... on a WRC rally stage... for 56 hours. To be honest, I would not expect drives to work having been repeatedly splashed, scratched, possibly rolled, and being covered in mud, so I am not sure the comparison stands, but you are right - for hard drives, the preclear process is a pretty good workout. I always do at least one and ideally three preclear cycles on new or previously used drives.
August 21, 201312 yr If you do not use Joe L's most excellent pre-clear, unRAID will 'clear' your drive anyway. While emhttp (unRAID) is clear ing your drive, your array is unavailable. The drive will then be inserted into the array even if there are pending sectors detected by SMART. It is highly recommended to pre-clear your drive. At the very least you will have a multi-pass test and output from the SMART data to make an educated decision as to the drive's viability in reliable storage.
August 21, 201312 yr Actually I think you missed the VERY least you get which is NO ARRAY DOWNTIME. That is the very least a pre-clear gets you and I consider that a pretty big deal when it takes about half day to clear a 2TB drive iirc. Smart reports are a bonus, eliminating infant-mortality failures is double-plus-bonus
August 21, 201312 yr Actually I think you missed the VERY least you get which is NO ARRAY DOWNTIME. That is the very least a pre-clear gets you and I consider that a pretty big deal when it takes about half day to clear a 2TB drive iirc. Smart reports are a bonus, eliminating infant-mortality failures is double-plus-bonus You're probably right.
Archived
This topic is now archived and is closed to further replies.