Hi,
I'm planning to install a storage server for a client, using an HP Proliant Microserver with 4 x 2 TB harddisks and RAID 5.
I have a similar configuration in my office, only with much smaller disks. Each disk is 250 GB. Here's what this looks like:
Code:
[root@nestor:~] # cat /proc/mdstat
Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4] [multipath]
md3 : active raid5 sda3[0] sdd3[3] sdc3[2] sdb3[1]
729317376 blocks level 5, 512k chunk, algorithm 2 [4/4] [UUUU]
md2 : active raid1 sda2[0] sdd2[3] sdc2[2] sdb2[1]
995904 blocks [4/4] [UUUU]
md1 : active raid1 sda1[0] sdd1[3] sdc1[2] sdb1[1]
96256 blocks [4/4] [UUUU]
unused devices: <none>
[root@nestor:~] # df -h
Sys. fich. Taille Util. Dispo Uti% Monté sur
/dev/md3 685G 517G 133G 80% /
/dev/md1 92M 38M 49M 44% /boot
tmpfs 1,5G 0 1,5G 0% /dev/shm
[root@nestor:~] # fdisk -l | grep sd | grep Disque
Disque /dev/sda*: 250.1*Go, 250059350016*octets
Disque /dev/sdb*: 250.1*Go, 250059350016*octets
Disque /dev/sdc*: 250.1*Go, 250059350016*octets
Disque /dev/sdd*: 250.1*Go, 250059350016*octets
In the example above, combining four 250 GB disks with RAID 5 results in 685 GB effective storage space.
Q: is there any formula or rule of thumb to calculate this storage space for disks with a different size, in my case 2 TB each?
Cheers,
Niki