After upgrading mdadm from released version mdadm-4.2 to the current git version the command mdadm --assemble --update=resync started failing with the error "mdadm: --update=resync not understood for 1.x metadata". My array superblock version is 1.0. I think this is a regression introduced by https://git.kernel.org/pub/scm/utils/mdadm/mdadm.git/commit/?id=7e8daba8b7937716dce8ea28298a4e2e72cb829e This commit deleted the "else if (strcmp(update, "resync") == 0)" code block without replacing it with a switch case. The following patch fixed the error for me. diff --git a/super1.c b/super1.c index dfde4629..6f23b9eb 100644 --- a/super1.c +++ b/super1.c @@ -1356,6 +1356,10 @@ static int update_super1(struct supertype *st, struct mdinfo *info, __cpu_to_le16(info->disk.raid_disk); break; } + case UOPT_RESYNC: + /* make sure resync happens */ + sb->resync_offset = 0; + break; case UOPT_UUID: copy_uuid(sb->set_uuid, info->uuid, super1.swapuuid); Regards, Andrea Janna
