I added a disk (a 3rd data disk) and all drives showed as unformatted.  Stopping and starting the array bought back the expected behaviour (just the new disk showing as unformatted).  Syslog attached - clearing ends at Apr 29 00:26:51 and then you can see "mount error: 32"'s.  Later on you can see where I bounced the array and the drives mounting cleanly.

 

Motherboard is Supermicro X7SPA-HF.

syslog.zip

Your log shows the same pattern as in other submitted logs. 

The initial attempt to mount the drives all fail

Apr 29 00:15:25 NAS emhttp: ... clearing 96% complete

Apr 29 00:18:10 NAS emhttp: ... clearing 97% complete

Apr 29 00:20:59 NAS emhttp: ... clearing 98% complete

Apr 29 00:23:52 NAS emhttp: ... clearing 99% complete

Apr 29 00:26:51 NAS emhttp: ... clearing 100% complete

Apr 29 00:26:51 NAS emhttp: ... syncing

Apr 29 00:26:53 NAS kernel: mdcmd (33): start PROTECTED_EXPANSION

Apr 29 00:26:53 NAS kernel: unraid: allocating 23340K for 1280 stripes (4 disks)

Apr 29 00:26:53 NAS kernel: md1: running, size: 1953514552 blocks

Apr 29 00:26:53 NAS kernel: md2: running, size: 1465138552 blocks

Apr 29 00:26:53 NAS kernel: md3: running, size: 976762552 blocks

Apr 29 00:26:53 NAS kernel: mdcmd (35): spindown 3

Apr 29 00:26:54 NAS emhttp: shcmd (39): mkdir /mnt/disk1

Apr 29 00:26:54 NAS emhttp: shcmd (39): mkdir /mnt/disk2

Apr 29 00:26:54 NAS emhttp: shcmd (39): mkdir /mnt/disk3

Apr 29 00:26:54 NAS emhttp: shcmd (41): mount -t reiserfs -o noacl,nouser_xattr,noatime,nodiratime /dev/md2 /mnt/disk2  >/dev/null 2>&1

Apr 29 00:26:54 NAS emhttp: shcmd (41): mount -t reiserfs -o noacl,nouser_xattr,noatime,nodiratime /dev/md1 /mnt/disk1  >/dev/null 2>&1

Apr 29 00:26:54 NAS emhttp: shcmd (42): mount -t reiserfs -o noacl,nouser_xattr,noatime,nodiratime /dev/md3 /mnt/disk3  >/dev/null 2>&1

Apr 29 00:26:54 NAS kernel: mdcmd (36): check

Apr 29 00:26:54 NAS kernel: md: recovery thread woken up ...

Apr 29 00:26:54 NAS emhttp: _shcmd: shcmd (42): exit status: 32

Apr 29 00:26:54 NAS emhttp: disk2 mount error: 32

Apr 29 00:26:54 NAS emhttp: shcmd (43): rmdir /mnt/disk2

Apr 29 00:26:54 NAS emhttp: _shcmd: shcmd (43): exit status: 32

Apr 29 00:26:54 NAS emhttp: disk1 mount error: 32

Apr 29 00:26:54 NAS emhttp: shcmd (44): rmdir /mnt/disk1

Apr 29 00:26:54 NAS emhttp: _shcmd: shcmd (44): exit status: 32

Apr 29 00:26:54 NAS emhttp: disk3 mount error: 32

Apr 29 00:26:54 NAS emhttp: shcmd (45): rmdir /mnt/disk3

 

Then, stopping and re-starting shows the disks being mounted (all but the one just cleared)

Apr 29 06:04:49 NAS kernel: mdcmd (2074): start STOPPED

Apr 29 06:04:49 NAS kernel: unraid: allocating 23340K for 1280 stripes (4 disks)

Apr 29 06:04:49 NAS kernel: md1: running, size: 1953514552 blocks

Apr 29 06:04:49 NAS kernel: md2: running, size: 1465138552 blocks

Apr 29 06:04:49 NAS kernel: md3: running, size: 976762552 blocks

Apr 29 06:04:50 NAS emhttp: shcmd (63): mkdir /mnt/disk2

Apr 29 06:04:50 NAS emhttp: shcmd (63): mkdir /mnt/disk3

Apr 29 06:04:50 NAS emhttp: shcmd (63): mkdir /mnt/disk1

Apr 29 06:04:50 NAS emhttp: shcmd (64): mount -t reiserfs -o noacl,nouser_xattr,noatime,nodiratime /dev/md3 /mnt/disk3  >/dev/null 2>&1

Apr 29 06:04:50 NAS kernel: mdcmd (2076): check

Apr 29 06:04:50 NAS kernel: md: recovery thread woken up ...

Apr 29 06:04:50 NAS emhttp: shcmd (65): mount -t reiserfs -o noacl,nouser_xattr,noatime,nodiratime /dev/md1 /mnt/disk1  >/dev/null 2>&1

Apr 29 06:04:50 NAS emhttp: shcmd (66): mount -t reiserfs -o noacl,nouser_xattr,noatime,nodiratime /dev/md2 /mnt/disk2  >/dev/null 2>&1

Apr 29 06:04:50 NAS kernel: md: recovery thread has nothing to resync

Apr 29 06:04:50 NAS emhttp: _shcmd: shcmd (66): exit status: 32

Apr 29 06:04:50 NAS emhttp: disk3 mount error: 32

Apr 29 06:04:50 NAS emhttp: shcmd (67): rmdir /mnt/disk3

Apr 29 06:04:50 NAS kernel: REISERFS (device md2): found reiserfs format "3.6" with standard journal

Apr 29 06:04:50 NAS kernel: REISERFS (device md2): using ordered data mode

Apr 29 06:04:50 NAS kernel: REISERFS warning (device md3): sh-2021 reiserfs_fill_super: can not find reiserfs on md3

Apr 29 06:04:50 NAS kernel: REISERFS (device md1): found reiserfs format "3.6" with standard journal

Apr 29 06:04:50 NAS kernel: REISERFS (device md1): using ordered data mode

 

Perhaps Tom @ lime-tech will see a pattern in what is happening.