Well it is tricky
1. creation time : all drives partitions including usb flash , got UUID , check that using root
create raid using /dev/sdx names , wich actually writes UUID into matrix
If somehow drives seX names get mixed , no worry , coz mdadm is UUID based , not sdX
my server output
Quote:
blkid
/dev/sda1: UUID="497b820b-f46c-755f-8f04-07357fb4c431" TYPE="linux_raid_member"
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Now , lets get some details about mdadm sda1
Quote:
mdadm --examine /dev/sda1
/dev/sda1:
Magic : a92b4efc
Version : 00.90.00
UUID : 497b820b:f46c755f:8f040735:7fb4c431
Creation Time : Fri Aug 15 10:04:28 2014
Raid Level : raid1
Used Dev Size : 976760768 (931.51 GiB 1000.20 GB)
Array Size : 976760768 (931.51 GiB 1000.20 GB)
Raid Devices : 2
Total Devices : 2
Preferred Minor : 0
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Please observe that mdadm sda1 UUID is identical with the one reported by blkid.
Let's insert an USB flash and run fdisk -l just to see it's dev name
Quote:
sudo fdisk -l
Disk /dev/sdg: 30.9 GB, 30943995904 bytes
32 heads, 20 sectors/track, 94433 cylinders, total 60437492 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 identifier: 0x0003c6ae
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Ok , got my flash in , it is partitioned otherwise there is no UUID
Quote:
sudo blkid
/dev/sdg1: UUID="be594716-681c-4fad-a71f-83c037666994" TYPE="xfs"
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see ? even USB flash got it's own UUID , which indeed differ from one machine to another , and differ even on same PC if repartitioning
Did once a raid 0 but cannot reach more than 40-50 MB/s even with 4 x kingston datatraveller 20Mb/s read, ,mainly coz USB 2.0 is limited to 480 Mb/s, but LED's light is great ,