I have been an unRaid user since May of last year. I run version 4.5.4 with Hitachi 2TB drives and no issues.  I have 5 drives in the array and I have one spare drive. My need for advice is regarding upgrading my Unraid firmware to either 4.7.x or 5.x.  I am not in any rush since things are working fine. I use unraid to hold all my movies, Music, Librarian files, backups, etc. I really don't want to lose anything although I do have all the original disks and could reconstruct in about a month of elapsed time.

 

I have read quite a bit hear about the 4K aligned drive issues, but am not sure I understand it.

 

Do the experts advise I Upgrade and if so to what/when? I have no equipment for a "Test facility"

 

Is it possible to run mixed aligned and not aligned drives and if so what firmware version and what are the caveats/bewares. 

 

Is there a process givenm a blank drive that has been set up as 4k aligned, to copy over all the data from a non aligned drive and then reset the non aligned drive to be cleared and 4K aligned? Is this advised, i.e should the array be consistent with regard to 4K alignment or does it not matter.

 

TIA

I have been an unRaid user since May of last year. I run version 4.5.4 with Hitachi 2TB drives and no issues.  I have 5 drives in the array and I have one spare drive. My need for advice is regarding upgrading my Unraid firmware to either 4.7.x or 5.x.  I am not in any rush since things are working fine. I use unraid to hold all my movies, Music, Librarian files, backups, etc. I really don't want to lose anything although I do have all the original disks and could reconstruct in about a month of elapsed time.

 

I have read quite a bit hear about the 4K aligned drive issues, but am not sure I understand it.

The "allignment" of the start of the unRAID partition to a 4k boundery is ONLY important if you have an "Advanced Format" drive that internally uses 4k sectors.

 

If you do, you will get better performance from the drive if the unRAID partitio is aligned at a 4k boudary, otherwise it will result in the need to read an extra sector when accessing a file.  (The first sector would contain the first 512 bytes of the file, and the next the subsequent 4k of the remainder)  When accessing small files, this added overhead is noticeable.

 

From what you've said, you have no Advanced Format drives.  You can upgrade to 4.7-beta1 or 5.0-beta2 at any time with no changes.

 

4.7beta1 has several bug fixes that are not in 5.0b2.  They should be in the 5.0b3 due out any day now.  There is a new setting for MBR-4k-aligned partitions.  If set, the unRAID partition will be created starting on sector 64 instead of sector 64 if there is not already a valid MBR or a pre-cleared signature in the MBR.

 

A drive with a partition starting on sector 64 is incompatible with earlier versions of unRAID.  To them, it will appear as unformatted.

Do the experts advise I Upgrade and if so to what/when? I have no equipment for a "Test facility"

I'd say if you are stable, wait until unRAID 4.7 is no longer bata.  Then use it.  Once 5.X gets a bit further on and 5.0 is stable, upgrade to it.

 

If you have problems with either of the bugs fixed in 4.7, then you might consider upgrading to the beta, but it does not sound like you do, so no rush.  You don't need to do anything special when you upgrade until you go to add a new disk, and even then, you do not need to do anything special as it will work regardless, even if the partition is not aligned on a 4k boundary.

 

There is a new preclear_disk.sh script to preclear and set a new preclear-signature that requests 4k-alligned partition in the MBR.

I suggest you download it.  It has an improved output format regardless of the version of unRAID you are using.

Is it possible to run mixed aligned and not aligned drives and if so what firmware version and what are the caveats/bewares. 

In version 4.7 yes. In version 5.0beta2 no.  In 5.0beta3 (due out shortly) yes.

Is there a process givenm a blank drive that has been set up as 4k aligned, to copy over all the data from a non aligned drive and then reset the non aligned drive to be cleared and 4K aligned? Is this advised, i.e should the array be consistent with regard to 4K alignment or does it not matter.

TIA

It does not matter at all unless you are using one of the new AF drive with 4k internal alignment. It really does not matter if everything is working for you regardless.

 

The difference in performance might be as little as a few percent, or as much as 20 percent if using a mis-aligned 4k AF drive, and neither may matter if you are only watching movies, since it does not need that last few percentage to read the drives.

 

Joe L.

AS usual a clear and concise answer.  Thanks Joe.  I really do appreciate it.