Questions[raid1](server)

I am running an unmanaged Ubuntu server and due to recent performance issue and sent a request to the provider only to receive the following response:

"Dear Client,

as requested we have checked your drives. Both drives pass a test without any error and do not show any critical value here. We noticed the RAID is degraded state so you will need to re-add the drive to array here:

-----------------%<-----------------
Personalities : [raid1]
md3 : active raid1 sda4[0]
      1839089920 blocks super 1.2 [2/1] [U_]

md2 : active raid1 sda3[0]
      1073610560 blocks super 1.2 [2/1] [U_]

md1 : active raid1 sda2[0]
      523968 blocks super 1.2 [2/1] [U_]

md0 : active raid1 sda1[0]
      16768896 blocks super 1.2 [2/1] [U_]

unused devices: <none>
-----------------%<-----------------"

Google says that U_ indicates a failed drive, which appears to be in contradiction to what the support said. How do I proceed from here?

Something like

mdadm /dev/mdX -r /dev/sdaY  
mdadm /dev/mdX -a /dev/sdaY  

And if so, what is X and Y for my case? If more info is needed about my configuration, please let me know.

EDIT, more info below:

root@Ubuntu-1204-precise-64-minimal /home # df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/md2       1008G   26G  931G   3% /
none            4.0K     0  4.0K   0% /sys/fs/cgroup
udev             16G  4.0K   16G   1% /dev
tmpfs           3.2G  504K  3.2G   1% /run
none            5.0M     0  5.0M   0% /run/lock
none             16G     0   16G   0% /run/shm
none            100M     0  100M   0% /run/user
/dev/md1        488M   66M  397M  15% /boot
/dev/md3        1.7T   31G  1.6T   2% /home

root@Ubuntu-1204-precise-64-minimal /home # mdadm -D /dev/md0
/dev/md0:
        Version : 1.2
  Creation Time : Wed Nov  6 08:02:41 2013
     Raid Level : raid1
     Array Size : 16768896 (15.99 GiB 17.17 GB)
  Used Dev Size : 16768896 (15.99 GiB 17.17 GB)
   Raid Devices : 2
  Total Devices : 1
    Persistence : Superblock is persistent

    Update Time : Wed Dec 21 03:50:13 2016
          State : clean, degraded
 Active Devices : 1
Working Devices : 1
 Failed Devices : 0
  Spare Devices : 0

           Name : rescue:0
           UUID : 872ad258:c42ccb36:e9e19c96:98b55ee9
         Events : 816844

    Number   Major   Minor   RaidDevice State
       0       8        1        0      active sync   /dev/sda1
       1       0        0        1      removed

root@Ubuntu-1204-precise-64-minimal /home # mdadm -D /dev/md1
/dev/md1:
        Version : 1.2
  Creation Time : Wed Nov  6 08:02:41 2013
     Raid Level : raid1
     Array Size : 523968 (511.77 MiB 536.54 MB)
  Used Dev Size : 523968 (511.77 MiB 536.54 MB)
   Raid Devices : 2
  Total Devices : 1
    Persistence : Superblock is persistent

    Update Time : Wed Dec 21 07:30:55 2016
          State : clean, degraded
 Active Devices : 1
Working Devices : 1
 Failed Devices : 0
  Spare Devices : 0

           Name : rescue:1
           UUID : 18cb39fc:9eaea61c:0074a6c2:661b5862
         Events : 387

    Number   Major   Minor   RaidDevice State
       0       8        2        0      active sync   /dev/sda2
       1       0        0        1      removed

root@Ubuntu-1204-precise-64-minimal /home # mdadm -D /dev/md2
/dev/md2:
        Version : 1.2
  Creation Time : Wed Nov  6 08:02:42 2013
     Raid Level : raid1
     Array Size : 1073610560 (1023.87 GiB 1099.38 GB)
  Used Dev Size : 1073610560 (1023.87 GiB 1099.38 GB)
   Raid Devices : 2
  Total Devices : 1
    Persistence : Superblock is persistent

    Update Time : Wed Dec 21 07:58:52 2016
          State : active, degraded
 Active Devices : 1
Working Devices : 1
 Failed Devices : 0
  Spare Devices : 0

           Name : rescue:2
           UUID : eb9be750:7ff778b4:31fd7ce9:9d86d191
         Events : 38799724

    Number   Major   Minor   RaidDevice State
       0       8        3        0      active sync   /dev/sda3
       1       0        0        1      removed

root@Ubuntu-1204-precise-64-minimal /home # mdadm -D /dev/md3
/dev/md3:
        Version : 1.2
  Creation Time : Wed Nov  6 08:02:42 2013
     Raid Level : raid1
     Array Size : 1839089920 (1753.89 GiB 1883.23 GB)
  Used Dev Size : 1839089920 (1753.89 GiB 1883.23 GB)
   Raid Devices : 2
  Total Devices : 1
    Persistence : Superblock is persistent

    Update Time : Wed Dec 21 07:57:41 2016
          State : clean, degraded
 Active Devices : 1
Working Devices : 1
 Failed Devices : 0
  Spare Devices : 0

           Name : rescue:3
           UUID : c9b748ef:332d3bf9:5fa8fef1:5b433b0a
         Events : 7429895

    Number   Major   Minor   RaidDevice State
       0       8        4        0      active sync   /dev/sda4
       1       0        0        1      removed

I have Suse Linux 12.1 and i am trying to mount a single RAID 1 disk, to explore the files in it. However when mounting it:

 # mount /dev/sdc1 /mnt/test
  mount: unknown filesystem type 'linux_raid_member' 

I started reading around and many advised to just force the filessystem type

  # mount -t ext4 /dev/sdc1 /mnt/test
  mount: /dev/sdc1 already mounted or /mnt/test busy

when trying

 umount /dev/sdc1                 
 umount: /dev/sdc1: not mounted

Could someone provide some advise?

I am running my machines insed an ESXI server and it is a virtual disk. However this should not play, as this disks are not used by any other machines

thaknks!

On the lvconvert(8) man page it says:

--type SegmentType
       Used to convert a logical volume to another segment type  or  to
       explicitly  state  the  desired  RAID1 segment type ("mirror" or
       "raid1") when converting a linear logical  volume  to  a  mirror
       with the '-m' argument.

But what exactly is the difference between "mirror" and "raid1"?

I've running Ubuntu 11.04 (kernel 2.6.38-11). I replaced 2x160GB with 2x500GB drives. They are configured as RAID1.

The partition tables show the right sizes. Here's sfdisk:

# sfdisk -d /dev/sdb
# partition table of /dev/sdb
unit: sectors

/dev/sdb1 : start=       63, size=   192717, Id=fd, bootable
/dev/sdb2 : start=   192780, size=  7807590, Id=fd
/dev/sdb3 : start=  8000370, size=968767695, Id=fd
/dev/sdb4 : start=        0, size=        0, Id= 0

And fdisk:

# fdisk -l /dev/sdb

Disk /dev/sdb: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0006c78f

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *           1          12       96358+  fd  Linux raid autodetect
/dev/sdb2              13         498     3903795   fd  Linux raid autodetect
/dev/sdb3             499       60801   484383847+  fd  Linux raid autodetect

But I'm not seeing the new space:

root@green:~# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/md2              143G  134G  8.3G  95% /


root@green:~# mdadm --examine /dev/sdb3
/dev/sdb3:
          Magic : a92b4efc
        Version : 0.90.00
           UUID : b8f83980:f60d820c:74c46fbf:0baa68bc
  Creation Time : Sun Mar 29 18:48:46 2009
     Raid Level : raid1
  Used Dev Size : 152247936 (145.19 GiB 155.90 GB)
     Array Size : 152247936 (145.19 GiB 155.90 GB)
   Raid Devices : 2
  Total Devices : 2
Preferred Minor : 2

    Update Time : Mon Oct 10 19:22:36 2011
          State : clean
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0
       Checksum : 7b5debb7 - correct
         Events : 10729526


      Number   Major   Minor   RaidDevice State
this     0       8       19        0      active sync   /dev/sdb3
   0     0       8       19        0      active sync   /dev/sdb3
   1     1       8        3        1      active sync   /dev/sda3

I tried mdadm and resize2fs:

# mdadm --grow /dev/md2 --size=max
mdadm: component size of /dev/md2 has been set to 152247936K

# resize2fs /dev/md2 
resize2fs 1.41.14 (22-Dec-2010)
The filesystem is already 38061984 blocks long.  Nothing to do!

Any ideas?

Added per request

# cat /proc/mdstat 
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] 
md2 : active raid1 sdb3[0] sda3[1]
      152247936 blocks [2/2] [UU]

md0 : active raid1 sdb1[0] sda1[1]
      96256 blocks [2/2] [UU]

md1 : active raid1 sdb2[0] sda2[1]
      3903680 blocks [2/2] [UU]

unused devices: <none>

partitions

# cat /proc/partitions 
major minor  #blocks  name

   8        0  488386584 sda
   8        1      96358 sda1
   8        2    3903795 sda2
   8        3  152248005 sda3
   8       16  488386584 sdb
   8       17      96358 sdb1
   8       18    3903795 sdb2
   8       19  152248005 sdb3
   9        1    3903680 md1
   9        0      96256 md0
   9        2  152247936 md2

parted:

# parted
GNU Parted 2.3
Using /dev/sda
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) print all                                                        
Model: ATA WDC WD5000AAKX-0 (scsi)
Disk /dev/sda: 500GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number  Start   End     Size    Type     File system     Flags
 1      32.3kB  98.7MB  98.7MB  primary  ext3            boot, raid
 2      98.7MB  4096MB  3997MB  primary  linux-swap(v1)  raid
 3      4096MB  500GB   496GB   primary  ext3            raid


Model: ATA WDC WD5000AAKS-4 (scsi)
Disk /dev/sdb: 500GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number  Start   End     Size    Type     File system     Flags
 1      32.3kB  98.7MB  98.7MB  primary  ext3            boot, raid
 2      98.7MB  4096MB  3997MB  primary  linux-swap(v1)  raid
 3      4096MB  500GB   496GB   primary  ext3            raid


Model: Linux Software RAID Array (md)
Disk /dev/md1: 3997MB
Sector size (logical/physical): 512B/512B
Partition Table: loop

Number  Start  End     Size    File system     Flags
 1      0.00B  3997MB  3997MB  linux-swap(v1)


Model: Linux Software RAID Array (md)
Disk /dev/md0: 98.6MB
Sector size (logical/physical): 512B/512B
Partition Table: loop

Number  Start  End     Size    File system  Flags
 1      0.00B  98.6MB  98.6MB  ext3


Model: Linux Software RAID Array (md)
Disk /dev/md2: 156GB
Sector size (logical/physical): 512B/512B
Partition Table: loop

Number  Start  End    Size   File system  Flags
 1      0.00B  156GB  156GB  ext3

Comment via email:

the problem is in metadata, you just need to assemble raid array with parameter --update devicesize

and after that -G /dev/md? -z max will done job :)

I am about to replace an old hardware RAID5 array with a Linux software RAID1 array. I was talking to a friend and he claimed that RAID5 was more robust than RAID1.

His claim was that with RAID5, on read the parity data was read to make sure that all the drives were returning the correct data. He further claimed that on RAID1 errors occurring on a drive will go unnoticed because no such checking is done with RAID1.

I can see how this could be true, but can also see that it all depends on how the RAID systems in question are implemented. Surely a RAID5 system doesn't have to read and check the parity data on a read and a RAID1 system could just as easily read from all drives on read to check they were all holding the same data and therefore achieve the same level of robustness (with a corresponding loss of performance).

So the question is, what do RAID5/RAID1 systems in the real world actually do ? Do RAID5 systems check the parity data on reads ? Are there RAID1 systems that read from all drives and compare the data on read ?