First let me say I am not a true expert, but I am experienced.
If this machine you purchased was some name brand, you must be speaking
about hardware raid, true? If this is true, it normally presents you
with what looks like a standard drive (/dev/sda) for every 2 drives
configured as raid-1. Also, most name brand servers give you a bootable
machine day one.
If you are using software raid, you must have configured it yourself.
Here is what my custom machine has:
2 - 120 GB SSD
2 - 4 TB spinning drives
During my CentOS 7 install is where I performed the software raid-1
configuration. I never do the default partition configuration so here is
my setup (used fdisk -l):
Disk /dev/sda: 120.0 GB, 120034123776 bytes, 234441648 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: 0x0001d7e8
Device Boot Start End Blocks Id System
/dev/sda1 2048 134604799 67301376 fd Linux raid
autodetect
/dev/sda2 134604800 184752127 25073664 fd Linux raid
autodetect
/dev/sda3 184752128 233191423 24219648 fd Linux raid
autodetect
/dev/sda4 233191424 234440703 624640 5 Extended
/dev/sda5 * 233195520 234440703 622592 fd Linux raid
autodetect
Disk /dev/sdb: 120.0 GB, 120034123776 bytes, 234441648 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: 0x000085a6
Device Boot Start End Blocks Id System
/dev/sdb1 2048 134604799 67301376 fd Linux raid
autodetect
/dev/sdb2 134604800 184752127 25073664 fd Linux raid
autodetect
/dev/sdb3 184752128 233191423 24219648 fd Linux raid
autodetect
/dev/sdb4 233191424 234440703 624640 5 Extended
/dev/sdb5 * 233195520 234440703 622592 fd Linux raid
autodetect
Disk /dev/sdc: 4000.8 GB, 4000787030016 bytes, 7814037168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk label type: gpt
# Start End Size Type Name
1 2048 1699579903 810.4G Linux RAID
2 1699579904 3399157759 810.4G Linux RAID
3 3399157760 3911510015 244.3G Linux RAID
4 3911510016 5611087871 810.4G Linux RAID
Disk /dev/sdd: 4000.8 GB, 4000787030016 bytes, 7814037168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk label type: gpt
# Start End Size Type Name
1 2048 1699579903 810.4G Linux RAID
2 1699579904 3399157759 810.4G Linux RAID
3 3399157760 3911510015 244.3G Linux RAID
4 3911510016 5611087871 810.4G Linux RAID
My df -h display shows me the following:
/dev/md126 583M 317M 224M 59% /boot
I have basically the definitions using CentOS 6 and CentOS 7 and it's my
understanding you must have a /boot device. Also during installation of
CentOS 7 when writing the MBR to the MD device (in my case md126) it
writes the information to both sda and sdb. With CentOS 6, according to
HowToForge there are extra steps required to get the MBR on both sda and
sdb.
I have not had to replace either of these SSD, but I have had to replace
spinning drives on my CentOS 6 machines in the past.
Gene
On 1/26/2017 7:00 AM, centos-request@xxxxxxxxxx wrote:
No. Brand new machine, pulled it out of the box and racked it. NOTHING on the
internal SSDs. Made an md RAID 0 on the raw disks - /dev/sda /dev/sdb. No
partitions, nothing. However, when I bring it up, fdisk shows an MBR with no
partitions. I can, however, mount /dev/md127p3 as /mnt/sysimage, and all is there.
Did I need to make a single partition, on each drive, and then make the RAID 1
out of *those*? I don't think I need to have /boot not on a RAID.
mark
------------------------------
--
Eugene Poole
Woodstock, Georgia
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