Is 16 terabytes Enough For Anyone?

At some point of life everyone starts to feel that 16Tb storage is no longer enough and it's time to expand it. I am a little scared to think how did I managed to currently occupy 12.68Tb. But there is no time to investigate, let's throw some hardware at the problem!

After routinely adding yet another 4Tb disk to RAID6 array and trying to resize ext4 partition I was puzzled by the message:

root@lbox2:/var$ resize2fs /dev/md1
resize2fs 1.43.4 (31-Jan-2017)
resize2fs: New size too large to be expressed in 32 bits

That was totally unexpected. EXT4 does not support partitions larger than 16Tb? It appeared that it did not up until somewhat recent time. 5 years ago that would have been a brick wall, 2 years ago I would have to wrestle a little with bleeding edge resize2fs/kernel and now it all works on-the-fly out of the box. One just need to convert this ext4 partition to 64-bit format:

root@lbox2:/var$ resize2fs -b /dev/md1
resize2fs 1.43.4 (31-Jan-2017)
Converting the filesystem to 64-bit.
The filesystem on /dev/md1 is now 3907015424 (4k) blocks long.

root@lbox2:/var$ resize2fs /dev/md1
resize2fs 1.43.4 (31-Jan-2017)
Resizing the filesystem on /dev/md1 to 4883769280 (4k) blocks.
The filesystem on /dev/md1 is now 4883769280 (4k) blocks long.

root@lbox2:/var$ mount /var/bigfatdisk

root@lbox2:/var/bigfatdisk$ df . -H
Filesystem      Size  Used Avail Use% Mounted on
/dev/md1         20T   14T  5.9T  71% /var/bigfatdisk

xy@lbox2:~$ cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md1 : active raid6 sdf1[0] sdg1[7] sdh1[6] sdc1[5] sdb1[3] sde1[2] sda1[1]
      19535077120 blocks super 1.2 level 6, 128k chunk, algorithm 2 [7/7] [UUUUUUU]
      bitmap: 1/466 pages [4KB], 4096KB chunk, file: /var/md1_intent.bin

unused devices: <none>

I remember in the late 90's i've been to ftp.cdrom.com - it had enormous 0.5Tb array: it felt like absolutely insane volume of data (I had 850Mb HDD at the time). Probably readers of this article in 2037 would have 1024-layer 3D phase-change memory with 64Tb in 2.5" drive. Good for you, readers from the future... Although it is also possible that popularization of online-content, streaming and cloud apps will make it almost obsolete to have large local storage (with a few exceptions).

BTW since I went for softraid at home about 8 years ago - I had not a single HDD failure (about 50 hdd-years). Still pays off - much less worries about at least 1 thing...