On Sun, Jan 15 2017, J. Cassidy wrote: > Hello all/Neil, > > > > > I am trying to change the chunk size on a RAID 0 (two SSD) from 512K to 64K. > > I am running Debian Stretch with a 4.10 kernel. > > MDADM version is 4.0 (GIT). > > This is the command string being issued - > > mdadm --grow -c 64 --backup-file=/zz/backup.file /dev/md0 > > or > > mdadm --grow -c 64 /dev/md0 > > both of the abovementioned commands produce this message - > > > "mdadm: /dev/md0: could not set level to raid4" > > > A snippet from dmesg - > . > . > md/raid:md0: cannot takeover raid0 with more than one zone. > md: md0: raid4 would not accept array Your two partitions that form the RAID0 array are different sizes. This causes raid0 to create 2 zones, one which covers all of the smaller partition and an equal portion of the larger partition, and one which covers the remainder of the larger partition. raid4 does not have a similar concept of zones, so it is not possible to convert the raid0 into a degraded raid4. raid0 does not support chunk-size changes (or any changes) directly. These are performed by transforming the RAID0 to RAID4 and having the raid4 module perform the change. The consequence of all this is that: sorry, you cannot change the chunk size of the array. And... please don't send nag emails so soon - it was barely more than 24hours after the original. This just comes across as rude and impatient. People have other commitments. My rule of thumb is to wait at least a week before resending - and then resend the full text of the original. Your nag email was not only too soon, but contained no detail and so was useless. NeilBrown > . > . > > My MDADM setup - > > > mdadm --detail /dev/md0 > /dev/md0: > Version : 1.2 > Creation Time : Sat Jan 14 16:51:54 2017 > Raid Level : raid0 > Array Size : 497783808 (474.72 GiB 509.73 GB) > Raid Devices : 2 > Total Devices : 2 > Persistence : Superblock is persistent > > Update Time : Sat Jan 14 16:51:54 2017 > State : clean > Active Devices : 2 > Working Devices : 2 > Failed Devices : 0 > Spare Devices : 0 > > Chunk Size : 512K > > Name : Pezenas:0 (local to host Pezenas) > UUID : 77cd6f4e:f98bf2b0:862948df:12da38fa > Events : 0 > > Number Major Minor RaidDevice State > 0 259 4 0 active sync /dev/nvme0n1p2 > 1 259 2 1 active sync /dev/nvme1n1p1 > > > I recall doing something similiar a few years ago and it worked, though not using > NVME drives. > > > Any help/pointers much appreciated. > > > > > Regards, > > > > John > > > > > > > John Cassidy > > Obere Bühlstrasse 21 > 8700 Küsnacht (ZH) > Switzerland / Suisse / Schweiz > > > Mobile: +49 152 58961601 (Germany) > Mobile: +352 621 577 149 (Luxembourg) > Mobile: +41 78 769 17 97 (CH) > Landline: +41 44 509 1957 > Mobile email: mobile@xxxxxxxxxxxx > > http://www.jdcassidy.eu > > "Aut viam inveniam aut faciam" - Hannibal.
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