On 04/17/2020 12:30 AM, Coly Li wrote:
Hi folks,
When I try to create md raid5 array with 4 NVMe SSD (3 for raid array
component disks, 1 for write log), the kernel is Linux v5.6 (not Linux
v5.7-rc), I find the md raid5 array cannot start.
I use this command to create md raid5 with writelog,
mdadm -C /dev/md0 -l 5 -n 3 /dev/nvme{0,1,2}n1 --write-journal /dev/nvme3n1
From terminal I have the following 2 lines information,
mdadm: Defaulting to version 1.2 metadata
mdadm: RUN_ARRAY failed: Invalid argument
From kernel message, I have the following dmesg lines,
[13624.897066] md/raid:md0: array cannot have both journal and bitmap
[13624.897068] md: pers->run() failed ...
[13624.897105] md: md0 stopped.
But from /proc/mdstat, it seems an inactive array is still created,
/proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md127 : inactive nvme2n1[4](S) nvme0n1[0](S) nvme3n1[3](S)
11251818504 blocks super 1.2
unused devices: <none>
From all the information it seems when initialize raid5 cache the bitmap
information is not cleared, so an error message shows up and raid5_run()
fails.
I don't have clear idea who to handle bitmap, journal and ppl properly,
so I firstly report the problem here.
So far I am not sure whether this is a bug or I do something wrong. Hope
other people may reproduce the above failure too.
Thanks.
Coly Li
Hi Coly
I can reproduce this. mdadm creates internal bitmap automatically if the
member device is bigger
than 100GB. raid5 journal device and bitmap can't exist at the same
time. So it needs to check this
when creating raid device.
diff --git a/Create.c b/Create.c
index 6f84e5b..0efa19c 100644
--- a/Create.c
+++ b/Create.c
@@ -542,6 +542,7 @@ int Create(struct supertype *st, char *mddev,
if (!s->bitmap_file &&
s->level >= 1 &&
st->ss->add_internal_bitmap &&
+ s->journaldisks == 0 &&
(s->consistency_policy != CONSISTENCY_POLICY_RESYNC &&
s->consistency_policy != CONSISTENCY_POLICY_PPL) &&
(s->write_behind || s->size > 100*1024*1024ULL)) {
I tried this patch. It can resolve this problem. How do you think about
this?
Best Regards
Xiao
