40+ TB of unRAID setup, want to add a new drive and avoid a long downtime?

[HiSoC8Y]

I should have sticked to my original plan, to preclear outside my live unRAID array, well, lesson learned!

[BobPhoenix]

Try running preclear with the -b, -w -r commands.  It doesn't limit the speed of preclear per-say but it does slow it down since you are limiting the read/writes and buffer to specific memory amounts.  That might allow access to your array to be more responsive while doing a preclear.  It might also do nothing but would be an option to try.

[BobPhoenix]

I should have sticked to my original plan, to preclear outside my live unRAID array, well, lesson learned!

That is how I have precleared 99% of my drives. 

[HiSoC8Y]

Try running preclear with the -b, -w -r commands.  It doesn't limit the speed of preclear per-say but it does slow it down since you are limiting the read/writes and buffer to specific memory amounts.  That might allow access to your array to be more responsive while doing a preclear.  It might also do nothing but would be an option to try.

 

thanks Bob, but I will stick to preclearing the other drive outside my unRAID box.  I will just download the free version of unRAID on a USB, and then use a USB enclosure with the HDD, connect it to my PC, and bypass both the unRAID and the USB to a VM, and do the preclearing there.

 

you think this will work?

[BobPhoenix]

Try running preclear with the -b, -w -r commands.  It doesn't limit the speed of preclear per-say but it does slow it down since you are limiting the read/writes and buffer to specific memory amounts.  That might allow access to your array to be more responsive while doing a preclear.  It might also do nothing but would be an option to try.

 

thanks Bob, but I will stick to preclearing the other drive outside my unRAID box.  I will just download the free version of unRAID on a USB, and then use a USB enclosure with the HDD, connect it to my PC, and bypass both the unRAID and the USB to a VM, and do the preclearing there.

 

you think this will work?

When I tried to preclear a disk via USB 3.0 on a Windows Host/unRAID 5.0 VM I got 50-60 MB/s speed (so slow) and the drive overheated because is was manufactured as an external drive.  Had I put an internal drive into a USB encloser with a fan it likely would have finished - but I do not know that for sure.

 

What I usually do is boot my desktop PC with unRAID free 5.0 and run preclear from there.  Since I have a laptop now the desktop is powered off 95% of the time so it is available for preclears.  When I run from the desktop I use a SATA cable and get full speed preclears.

[garycase]

Agree that using a direct SATA connection is MUCH better than using USB.  Other than that, it's certainly not a bad idea to just use another system for the pre-clears.

 

You can make it really easy to do this by adding an eSATA bracket to your desktop, as long as you have an unused internal SATA port.

 

[garycase]

...meant to provide these links: 

 

e-SATA bracket with a single data output:

http://www.monoprice.com/Product?seq=1&kpid=7637&format=2&p_id=7637&CAWELAID=1329454711&CAGPSPN=pla%26catargetid=320013720000066114%26cadevice=c&gclid=CPq_yN365MQCFQcpaQodWBUAVg

 

e-SATA bracket with power in addition to data output:

http://www.ebay.com/itm/2-Ports-eSATA-4-Pin-Power-PCI-Bracket-Slot-SATA-Cable-SC2-/180695788621

 

The first is all you need if you have an external e-SATA docking unit with its own power.  The second is convenient if you also need power.