Forum Discussion

Sensei

Sep 14, 2019

Non-optimal partition alignment

I have a non-Netgear SAS expansion chassis connected to my RD5200 running OS6, so I have to manually create volumes via SSH. When I do that, I am careful to create an OS and swap partition exactly a...

StephenB

Guru - Experienced User

Sep 15, 2019

Sandshark wrote:
Anyway, when I do create these, parted warns me that the resulting partitions are not aligned for optimal performance. Fdisk and gdisk refuse to even create that alignment. Is this affecting the speed of ReadyNAS devices?

My RN526 disks are partitioned this way:

Device           Start         End     Sectors  Size Type
/dev/sda1           64     8388671     8388608    4G Linux RAID
/dev/sda2      8388672     9437247     1048576  512M Linux RAID
/dev/sda3      9437248 11721041071 11711603824  5.5T Linux RAID
/dev/sda4  11721041072 19532873679  7811832608  3.7T Linux RAID

Note the data volume was vertically expanded (which is why /dev/sda4 exists). All of these start on 4K boundaries.

I believe parted (and gdisk) presume the optimal alignment is to start all partitions on 1 MiB boundarys (2048 sectors) - and the ReadyNAS isn't doing that. But I don't think there is any performance degradation in the NAS setup. As best I can tell, the motivation for the 1 MiB value is only to be conservative over the long term. AFAICT, 4K alignment is enough to give optimal performance with current disks.

Sandshark
Sensei
Sep 15, 2019
Yep, that's the way they normally are, and the observations I made still apply. Parted complains they are non-optimal and fdisk and gdisk refuse to do it. But Parted will let you do it and just complain when done in a single commend or make you confirm if done one at a time.

I read much of what you said in other forums, that fdisk and gdisk are going with a conservative "one size fits all" approach. But was wondering if anyone from Netgear would comment on specifics for the NAS and if there is an impact for larger drives without 512N sectoring. If not now, in the future.