(original article)

Re: Converting RAID5 to RAID6 and other shape changing in md/raid

15 November 2010, 14:18 UTC

I have a raid of 7x2TB disks running in raid6 with mdadm. Works great and has been doing so for some time now! Thanks for the great mdadm software and the work you put into it!

I am thinking about adding a couple of new 2TB disks, and see that now there is "Advanced Format" disks availabale that uses 4k sectors instead of the old 512bytes. I have read that this might be a bad thing for small files, and I guess that impacts the usage of raid such as mdadm? I read this " When creating a RAID array from Advanced Format disks, you don't need to take any extra steps. Because the RAID alignment values are multiples of the 4096-byte alignment required by Advanced Format drives, both technologies' needs are met if you align partitions as for a RAID array of disks with 512-byte physical sectors" (source : https://www.ibm.com/developerworks/linux/library/l-4kb-sector-disks/)

Any input on how this would impact the raids would be great! Do I have to tune chunk-size with this is mind? Should I avoid mixing 512bytes drives with 4k?