no one answered the last question, maybe it was to long winded, should i bother to pre clear drives that i am migrating my server to ?..as soon as all the data is on my unraid system i will take the drives from the old system and use them and want to take the ones i migrated to out

no one answered the last question, maybe it was to long winded, should i bother to pre clear drives that i am migrating my server to ?..as soon as all the data is on my unraid system i will take the drives from the old system and use them and want to take the ones i migrated to out

If you've never read and written EVERY byte on the disk, then a preclear will detect any un-readable sectors.

 

If the disk has any sectors pending re-allocation, they "should" be re-allocated when it is written.  You'll not know if it can be read until you perform a verify test.    (Don't overwrite your original disks until you have verified you can read what you've migrated AND it is protected by parity)

 

Joe L.

If you do not use pre-clear, then when you add the new drives into the unRAID array, they will be cleared by emhttp anyway.

 

This could take hours and hours for large drives.

You're not saving all that much time by not pre-clearing and you are saving time and headache by pre-clearing because you will have tested the drive and will have a higher level of confidence.

 

Plus you can use the array while the preclear is running.

If emhttp does the clear, the array is unusable until that is finished.

 

By the time it's taken to communicate should I or shouldn't I... it could have been started and done already. (no ill intention is meant by this).

Preclear is... set it.... run it..  come back in a day and check it's status..... It's easy and worth it.

 

ALSO As you copy files from one server to the other. Use teracopy in TEST mode if possible.

It tests that what was read is the same as what is read back. it will take some extra time, but you will know what it succeeded or failed.

Thanks guys, ..i really need to get some real basic linux in me..this is going soooooooo slow for me.

 

ok,  the parity drive will need to be as big or bigger that any other drive in the unit correct ?...all the 2 tb one (four of them) are in the QNAP nas right now..i only have 3 x1tb and 2 x500gb and 1 x 320gb in the unraid unit ready to take the data off the 2tb ones in the QNAP...should i remove one of the 500gb drives before i preclear and when the data is finished migrating, put the first 2 tb in there as a parity drive then start swapping out the other smaller drives for the other 2tb ones ??..im just not sure of how i should flow this

 

 

right i have started preclearing all the drives, its starting to dawn on me now i am not going to be able to do this without buying a 2TB drive..reason being, all the drives i intend to put in the UNraid setup are all 2TB and currently in the QNAP with my data on them with no way of shrinking the RAID5 to allow me to remove one, i thought of possibly just pulling one and then sticking in one of the 1TB ones and allow it to rebuild onto that, thus freeing me a 2TB  but it wont work because the QNAP has to have all the same size drives else it will render all other drives as the same size of the smallest in the array. The only possible way to do it without shelling out for another 2TB is to migrate over without having a parity drive in place, leave one of the slots free and when the migrate is over then stick in one of the 2TB from the QNAP, preclear it and add it as the parity drive..which will leave me at risk for at least 24 hours...does anyone have any other ideas on this ?

Moving you data off the NAS and putting it on unraid without parity protection is risky. Are the drives in the current unraid setup precleared? You could also use one of the 1tb drives as a parity drive until you get the data of the nas and just swap it out for one of the 2tb drives.

They will be. they are preclearing now. so allkcate the 1tb as parity then swap it out for 2tb after migration and rebuild parity agai

n