Raid 1 across 10 drives

[Ranjith M]

Hello All,

If iam creating logical drives across 10 drives with raid 1, where will be the mirrored data resides??

Please explain me the data write to disks.

Regards,

Ranjith

[Torsten.]

How to explain anything if you don't tell about the device used?

Is it a JBOD, a MSA, a EVA, ...

[Ranjith M]

Its a MSA

[Torsten.]

this is hard work ...

MSA20/30/50/60/70/1000/1500 ???

Connected to what?

[Víctor Cespón]

That would be a RAID 1+0. The data is divided in 5 sets, then each set is writed to 2 disks.

[Ranjith M]

If data is divided in 5 sets, howz the mirror set formed? by controller?

And if raid 1 is formed across 3 disks. data will be written across three disk rt? which disk mirrored data resided, is that to a specific disk or it will be distributed among the 3 disks?

[Torsten.]

Be careful about RAID 1 and RAID 1+0!

This will give you an idea:

http://bizsupport.austin.hp.com/bc/docs/support/SupportManual/c00386950/c00386950.pdf

Table 1. Summary of RAID technologies for large arrays - page 4

[Víctor Cespón]

RAID 1+0 needs an even number of disks, you cannot use just 3 disks. The idea is always the same, divide the data in parts (RAID 0), but write each part to 2 disks (that's why you need an even number).
You can lose several disks as long as they are not from the same pair.

[Ranjith M]

so for Raid 1 and Raid 0 etc... we need even number of disks???

[Torsten.]

Again, be careful with names!

RAID0 is not RAID1 is not RAID0+1!

For any "mirrored" config you need an even number of drives.
Did you already read the document posted earlier?