[SOLVED] Preclear options for very large drives

[bretzlaff]

Ok, I've read the forums and have had out of memory errors and other problems and determined it's caused by my default use of preclear_disk.sh with default parameters.

 

I'd like to use -r -b and -w but need a recommendation on appropriate settings.

 

I need to preclear 2 or 3 3TB drives at the same time, as well as clear 3 1.5 TB drives later.  I'd like to use appropriate values without slowing it down too much.

 

I have 4 Gig allocated and have a cache drive so I could easily use the swap file if that would help.  I am also running 5rc5 if that matters.

 

What would be a good value for the -r, -w, and -b settings?

 

       -w size  = write block size in bytes

       -r size  = read block size in bytes

       -b count = number of blocks to read at a time

 

Thanks,

Brad

unRaid Plus user for 30 days or less

[dgaschk]

I typically clear six 2 or 3T drives at the same time using only 2G RAM. What else is using the memory?

[bretzlaff]

dgaschk,

 

This was prompted by my problems in this thread http://lime-technology.com/forum/index.php?topic=22394.0 and a forum search that led me here http://lime-technology.com/forum/index.php?topic=21291.msg192198;topicseen#msg192198 where Joe mentions:

 

The two pre-clears alone would use the bulk of memory unless you used the-r -w and -b options to limit their memory usage.

 

That's how I came to ask about the options for preclear. 

 

Thanks,

Brad

[Joe L.]

dgaschk,

 

This was prompted by my problems in this thread http://lime-technology.com/forum/index.php?topic=22394.0 and a forum search that led me here http://lime-technology.com/forum/index.php?topic=21291.msg192198;topicseen#msg192198 where Joe mentions:

 

The two pre-clears alone would use the bulk of memory unless you used the-r -w and -b options to limit their memory usage.

 

That's how I came to ask about the options for preclear. 

 

Thanks,

Brad

I would definitely choose a multiple of 512 bytes for the -w and -r options.    32768 or 65536 might be good numbers to try.

For -b, try 500 or 1000.    (500 * 32768 = 16Meg of memory read at a time)

[bretzlaff]

Excellent information. 

 

Thanks