A couple months ago I set up my first unraid box and am thrilled with it. I have it playing nicely with all my OS X and Linux boxes.

When I first started playing with it I just downloaded the trial 4.7 and threw in 3 drives I had around:

WD Blue - WD6400AAKS

WD Blue - WD5000AAKS

WD Green - WD10EARS

 

After deciding I liked unraid, I picked up a WD20EARS and put it in as a parity drive. I didn't do any preclears, but the first three drives had been in use for a while previously.

 

I picked up a Hitachi Deskstar 5K3000 2TB yesterday and my goal is to replace one of the WD Blues and use the Blue as a Cache drive.

 

I started the preclear on the Deskstar last night but didn't set the 4k flag (I'll set the flag on the next preclear).

 

So here are my questions...

If I set the MBR 4K flag in the unraid web interface what will it do to my current data drives?

Should I swap the Deskstar in as the parity drive after it's formated as 4k and then preclear the WD20EARS as a 4k drive and swap the WD20EARS in as a replacement for the Blue?

If the 4k flag is set in the unraid interface, how will that affect the WD Blue when I set it as the cache drive?

 

So many questions... this 4k stuff has my head spinning.

 

So here are my questions...

If I set the MBR 4K flag in the unraid web interface what will it do to my current data drives?

It will do absolutely nothing.  It is only used if the drive is brand new and has never been either pre-cleared (which defines the partition start) or assigned to the array (which also defines the start of the partition)

Should I swap the Deskstar in as the parity drive after it's formatted as 4k

You could, but it will have absolutely no affect being formatted with the partition starting on sector 64 vs. starting on sector 63.  The Deskstar is not an "advanced format drive whose performance is not as high if not accessed on 4k boundaries.

and then preclear the WD20EARS as a 4k drive and swap the WD20EARS in as a replacement for the Blue?

Only if you have NOT added a jumper to the drive to have it logically add one to sectors being requested.  Otherwise, if you did add a jumper, it is already working as best it can.

If the 4k flag is set in the unraid interface, how will that affect the WD Blue when I set it as the cache drive?

Depends.  Unless you zero out the current disk partition, it will have no effect at all. once partitioned, via either the pre-clear script, or assignment to the array in any way, the partition start will not be changed.  the setting on the management interface is ONLY used when it is initially setting a partition.  unRAID only does that if the disk has not been pre-cleared and does not already have a valid disks partition similar to the one it would create.

 

Joe L.

 

Thanks for the tip Joe on the 5K3000 not being an "advanced format drive" I guess I assumed that all new 2TB-3TB drives were like the WD's.... no idea why I assumed that. Guess I've just been living in a WD world for too long. (We use a ton of WD drives and Drobo's at work).

 

Guess I'll just swap the 5K3000 in as the parity drive once it's finished it's preclear and let unraid rebuild parity.

Then preclear the WD20EARS as a 4k drive and replace WD5000AAKS with it and unraid rebuild the data onto it.

Then assign the WD5000AAKS as the Cache drive.

 

Sound reasonable? Thanks for tolerating us NUBs!!!!