preclear disks

[Fork]

I have transferred several TBs to my array and completed several parity checks with no errors.  however i did not preclear my disks.  is it necessary to do so? im guessing if i do it now, all the data on the disk will be lost

 

on another note, the wiki says that write speeds to the array with parity on should be 15-25 mb/sec.  however, i'm getting a constant 30+mb/sec.  not that im complaining, im just wondering if its plausible to have such a write speed.  im writing to 7200rpm hitachi deskstar 2tb drives with no cache.

[Joe L.]

I have transferred several TBs to my array and completed several parity checks with no errors.  however i did not preclear my disks.  is it necessary to do so? im guessing if i do it now, all the data on the disk will be lost.

You can not clear them now.  You can run a series of parity "checks"  They will read all the blocks on the disks.  It is the best you can do without un-assigning the drive and erasing your data in the process.

 

on another note, the wiki says that write speeds to the array with parity on should be 15-25 mb/sec.  however, i'm getting a constant 30+mb/sec.  not that im complaining, im just wondering if its plausible to have such a write speed.  im writing to 7200rpm hitachi deskstar 2tb drives with no cache.

The newest of unRAID versions have improved performance.  The wiki is out-of-date for faster drives and the most current version of unRAID.. As you said, you can not complain.

[barrettj]

Preclearing is for when you want to add a disk to an already running array and want to minimize the downtime involved (adding a new disk requires having all bits on that disk set to 0 as to not affect the parity of the already running system).

 

If you are already up and running and not adding a disk, you would get no benefit from preclearing (and yes it would cause all data on the disk to be lost, it's literally clearing the entire drive bit by bit).

 

As to your write speed question, I believe the documentation is out of sync with the latest updates regarding performance (it's been made faster).

[Fork]

ok thank you