Setting up RAID10 question/issue

XYNaPSE · 02-02-2017, 07:58 PM

Hello,

I have a CENTOS 7 server with 4 120GB SSD drives. RAID10 is being used. To my understanding of RAID10 I thought 240GB would be available but only 120GB is showing. I have never set up RAID before so if this needs to be moved to the newb section I understand. If someone could help me understand. I do see the 4 drives listed. I'm thinking one needs to be mounted and I'm not sure which one or I'm wrong about being able to use 240GB. Thank you in advance for responses.

Code:

[root@web1 ~]# df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/md1        117G  9.8G  101G   9% /
devtmpfs        7.8G     0  7.8G   0% /dev
tmpfs           7.8G     0  7.8G   0% /dev/shm
tmpfs           7.8G   33M  7.8G   1% /run
tmpfs           7.8G     0  7.8G   0% /sys/fs/cgroup
/dev/md0       1007M  138M  819M  15% /boot
tmpfs           1.6G     0  1.6G   0% /run/user/0

Code:

[root@web1 ~]# mdadm --examine --scan
ARRAY /dev/md/0  metadata=1.0 UUID=a693e28d:189b0726:faa3dce2:16eb2f11 name=web1.quantumspider.com:0
ARRAY /dev/md/1  metadata=1.2 UUID=04d77c92:7650f23e:836ca662:be05e9ab name=web1.quantumspider.com:1

Code:

/dev/md0:
        Version : 1.0
  Creation Time : Wed Feb  1 22:22:12 2017
     Raid Level : raid1
     Array Size : 1047488 (1022.94 MiB 1072.63 MB)
  Used Dev Size : 1047488 (1022.94 MiB 1072.63 MB)
   Raid Devices : 4
  Total Devices : 4
    Persistence : Superblock is persistent

  Intent Bitmap : Internal

    Update Time : Thu Feb  2 23:59:13 2017
          State : clean
 Active Devices : 4
Working Devices : 4
 Failed Devices : 0
  Spare Devices : 0

           Name : web1.quantumspider.com:0  (local to host web1.quantumspider.com)
           UUID : a693e28d:189b0726:faa3dce2:16eb2f11
         Events : 23

    Number   Major   Minor   RaidDevice State
       0       8        2        0      active sync   /dev/sda2
       1       8       18        1      active sync   /dev/sdb2
       2       8       34        2      active sync   /dev/sdc2
       3       8       50        3      active sync   /dev/sdd2

Code:

[root@web1 ~]# mdadm --detail /dev/md1
/dev/md1:
        Version : 1.2
  Creation Time : Wed Feb  1 22:21:18 2017
     Raid Level : raid1
     Array Size : 123919360 (118.18 GiB 126.89 GB)
  Used Dev Size : 123919360 (118.18 GiB 126.89 GB)
   Raid Devices : 4
  Total Devices : 4
    Persistence : Superblock is persistent

  Intent Bitmap : Internal

    Update Time : Thu Feb  2 20:51:44 2017
          State : clean
 Active Devices : 4
Working Devices : 4
 Failed Devices : 0
  Spare Devices : 0

           Name : web1.quantumspider.com:1  (local to host web1.quantumspider.com)
           UUID : 04d77c92:7650f23e:836ca662:be05e9ab
         Events : 536

    Number   Major   Minor   RaidDevice State
       0       8        3        0      active sync   /dev/sda3
       1       8       19        1      active sync   /dev/sdb3
       2       8       35        2      active sync   /dev/sdc3
       3       8       51        3      active sync   /dev/sdd3

Code:

[root@web1 ~]# fdisk -l

Disk /dev/sdc: 128.0 GB, 128035676160 bytes, 250069680 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x0002fbc0

   Device Boot      Start         End      Blocks   Id  System
/dev/sdc1            2048        4095        1024   83  Linux
/dev/sdc2   *        4096     2099199     1047552   fd  Linux raid autodetect
/dev/sdc3         2099200   250068991   123984896   fd  Linux raid autodetect

Disk /dev/sdb: 128.0 GB, 128035676160 bytes, 250069680 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x000028d1

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048        4095        1024   83  Linux
/dev/sdb2   *        4096     2099199     1047552   fd  Linux raid autodetect
/dev/sdb3         2099200   250068991   123984896   fd  Linux raid autodetect

Disk /dev/sdd: 128.0 GB, 128035676160 bytes, 250069680 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x0005a213

   Device Boot      Start         End      Blocks   Id  System
/dev/sdd1            2048        4095        1024   83  Linux
/dev/sdd2   *        4096     2099199     1047552   fd  Linux raid autodetect
/dev/sdd3         2099200   250068991   123984896   fd  Linux raid autodetect

Disk /dev/sda: 128.0 GB, 128035676160 bytes, 250069680 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x000c9a7d

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1            2048        4095        1024   83  Linux
/dev/sda2   *        4096     2099199     1047552   fd  Linux raid autodetect
/dev/sda3         2099200   250068991   123984896   fd  Linux raid autodetect

Disk /dev/md1: 126.9 GB, 126893424640 bytes, 247838720 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/md0: 1072 MB, 1072627712 bytes, 2094976 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

syg00 · 02-02-2017, 08:10 PM

RAID1 perhaps ?. Check the listings you provided.

XYNaPSE · 02-02-2017, 08:26 PM

Quote:

Originally Posted by syg00

RAID1 perhaps ?. Check the listings you provided.

I see it does say RAID1 but even then shouldn't it show 240GB available? Sorry I'm lost.

To my understanding in RAID 10, 2 sets of 2 drives each will use Raid 1 while those 2 sets of drives use RAID 0 and that is how RAID 10 works and why 4 drives are required. So I thought that 240GB would be available as 2 drives 120GB each.

The datacenter I'm using has the option to provision the server. I chose Centos7 with Soft Raid 10 (4 disks sda sdb sdc sdd)

XYNaPSE · 02-02-2017, 08:59 PM

I think I understand now. It must have not setup RAID10 and I will have to start over.

mdadm --detail /dev/md0
mdadm --detail /dev/md1

Should both show Raid Level : RAID 10 but instead show RAID 1

syg00 · 02-02-2017, 09:01 PM

RAID1 isn't RAID10.
RAID1 has no striping, so you will get 4 copies of the data - one plus 3 mirrors. Size is limited to (smallest) extent size.

Edit: looks like our posts crossed "in flight".

XYNaPSE · 02-02-2017, 09:23 PM

Quote:

Originally Posted by syg00

RAID1 isn't RAID10.
RAID1 has no striping, so you will get 4 copies of the data - one plus 3 mirrors. Size is limited to (smallest) extent size.

Edit: looks like our posts crossed "in flight".

Ok thank you.

Back to square 1.

XYNaPSE · 02-03-2017, 03:01 PM

The problem was the datacenter had an error in the installation profile. It has been corrected. Kudos to me for trying to figure it out with out bothering IT support.

In the end it was inevitable. Anyway, I learned a lot more about RAID because of it.