OK, I am starting this as a new thread because I don't want to see it get lost in the shuffle of the main thread discussing EARS drives in general.  When 4.7 was released one of the key features was the support of EARS and other Advanced format drives.  The difference between WD EARS and other drives was that WD allowed for the application of a jumper to pins 7/8 and then the drive was I guess tricked to being "normal", NOT advanced format.  This meant that you can keep using these drives with 4.6 and you format them like normal using preclear, WITHOUT the -A command.

 

The big question I know was always about performance.  Would a EARS drive with the jumper perform as well as one running 4.7 4k-Alligned without a jumper and the answer was yes.  For this reason it was said if you are on 4.6 with jumpered EARS drives you should simply leave the jumper in place when you move to 4.7 and then going forward you can add new drives without the jumper.  I thought I understood this process, so when I recently added 2 new drives to my 4.6 system, I added the jumper and formatted without the -A command.  At the time I added the drives, 4.7 was still beta, so I resisted the urge until recently.

 

So, finally I managed to move to 4.7 and wanted to replace a 1TB drive with a 2TB EARS.  I thought the process was to preclear with -A and add to the array with MBR set to 4k-aligned, but I wanted to make sure so took a quick peek at the forums.  However, as I began reading I started getting confused because things were not clearly defined for my situation and for this reason I wanted to start this thread.

 

My current Array consists of EADS (non-advanced format) and EARS (Advanved Format with jumper, pre-cleared without the -A).  I was running 4.6 till yesterday when I moved to 4.7.  I want to add a new drive and am curious as to what and how I should do this.  I also want to know what I should do with my existing jumpered EARS drives and lastly I want to know what setting I should use for MBR.

 

Now a few scenarios:

1. leave MBR: unaligned, leave all existing drives as is and always add new EARS drives with the jumper on 7/8 and pre-clear them without the -A command.  This obviously will work and nothing is changing except that I am running 4.7 instead of 4.6, otherwise drives continue to be added in the same manner and I just need to ensure I have jumpers when I add drives...

 

2. Switch MBR to 4k-Aligned, leave all exisitng drives alone, non-EARS and jumpered EARS drives remain in tact, but going forward all new EARS drives will be added without the jumper and will be pre-cleared with the -A option.  When 4.7 was first in beta with the 4k-alignment option I thought this was the way to go, but when reading the forums, this thought changed and now I am under the impression that this will degrade performance.  Is this true?  Will a jumpered EARS drive that was pre-cleared WITHOUT the -A command perform poorly if MBR is now switch to 4k-Aligned?

 

3. Switch MBR to 4k-aligned and let the fun begin.  With this method the only drives that don't change are the non-EARS advanced format drives, they dont care about the 4k-aligned option and will perform the same if the setting is set to 4k-aligned or unaligned.  However, all other drives will be affected.  All new drives will be added without jumpers and will be pre-cleared WITH the -A command and added to the array and will perform at top speed.  Then, all existing JUMPERED EARS drives will need to be re-built in essence, using the following:

 

TO REMOVE THE JUMPER ON AN EARS DRIVE ALREADY IN THE ARRAY

 

1 - Make sure the unRAID alignment setting is "4K aligned"

2 - Take a screenshot of the unRAID main page.  Save it in a JPG or print it out.

3 - Stop the array

4 - Unassign the disk from the array

5 - Start the array (may need to check the checkbox to start the array) - THIS IS VERY IMPORTANT.  Array must be started with disk missing.

6 - Stop the array

7 - Power down

8 - Remove the jumper

9 - Power up

10 - From telnet prompt run the following commad.  This clears the MBR and is necessary to change the partition alignment.

 

dd if=/dev/zero count=200 of=/dev/sdX

 

where sdX the is device.  Look on unmenu, myMain or the unRAID devices page for the 3 letter device code (e.g., sda, sdb, ...)

 

11 - Reboot (click reboot buttong on unRAID GUI)

12 - Array should not start automatically.  DO NOT START IT YET!

13 - Preclear (optional - if you precleared it when it was new and it is not giving trouble, no need to preclear it again)

14 - Verify that the unjumpered disk is assigned to its prior slot (e.g., if this was disk3, make sure the disk is again assigned to disk3)

15 - If not - go to the devices page and assign it to the devices page

16- Go to main page and compare it to the screenshot taken in step 2

17 - You should see unRAID saying that it will rebuild the disk.  (You may need to click a checkbox to enable the start button)

18 - Start the array

19 - Disk will rebuild, let it finish

20 - Verify contents of rebuilt disk

Using this above method, is the only way to maintain maximum performance. Otherwise, if you use 4k aligned and unjumpered EARS drives pre-cleared with -A they will perform as expected and the same goes for the older EADS/non-Advanced format drives.  However, with this method, all existing EARS drives with the jumper in place and were pre-cleared WITHOUT the -A will all take a perfoemance hit and suffere from degraded performance.  Is this right?

 

Essentially, with this thread I am trying to figure out the RIGHT way to do things or maybe just a prefered method with which to maintain performance.  Can jumpered (pre-cleared WITHOUT -A) and un-jumpered (pre-cleared WITH -A) co-exist when MBR is set to 4k-aligned while still maintainig performance?  Or is it one way or another, meaning MBR:unaligned and all EARS drives will get jumpers and be pre-cleared without -A OR MBR:4k-aligned and all new EARS drives get no jumper and will be pre-cleared with -A and also all exisitng jumpered EARS drives need to have the jumper removed and they need to be fixed and rebuilt to support MBR:4k-aligned?

 

Hopefully my questions and points are clear.  If not and there is confusion please let me know.  

The 4k-alignment setting only applies to drives that are new to the array. Existing drives are not effected. Enabling 4k-alignment does not effect existing disk at all.

 

Enable 4k-alignment. Make sure that you have the latest pre-clear script. Format all new drives with the -A option, although you don't need to add -A because the latest pre-clear will honor the 4k-alignment setting in unRAID by default.

 

Don't do anything with existing drives. The only reason to touch an existing drive is if it is an AF drive formatted as 4k-UNaligned (except for EARS drives with jumpers). EARS drives with jumpers will perform optimally when formatted as 4K-UNaligned.

 

 

OK, this is perfect, but I want to ensure I understand this statement.

 

Don't do anything with existing drives. The only reason to touch an existing drive is if it is an AF drive formatted as 4k-UNaligned (except for EARS drives with jumpers). EARS drives with jumpers will perform optimally when formatted as 4K-UNaligned.

 

Exisiting drive = ANY drive in the current array that is or isnt AF and if it is AF, it has a jumper and was formatted without the -A in any pre-4.7 release.

 

EARS drives with jumpers will perform optimally when formatted as 4K-UNaligned., this references existing drives right?  Meaning those with jumpers, cleared without the -A in pre-4.7

 

So, if the above is true, I should switch to MBR:4k-aligned, leave all my jumpered AF EARS drives alone as well as non-AF drives.  And the only thing that will change moving forward is all new EARS AF drives will be added without the jumper and pre-cleared with -A (or without as referenced saying pre-clear v1.9 knows if 4k-aligned is set).  And by doing this and not changing my old disks (including jumpered EARS AF drives), everything will continue to perform optimally and I can move on with my life and stop worrying...

And by doing this and not changing my old disks (including jumpered EARS AF drives), everything will continue to perform optimally and I can move on with my life and stop worrying...

exactly.

Awesome!  Thanks guys, not sure how I got so twisted up last night.  I am just glad I was able to get things straightened out.  Now back to replacing my one disk and not changing the rest.  My word I was nervous.