RAID-0, RAID-1 on Guardian MAXimus

[lukasc]

RAID-0, RAID-1 on Guardian MAXimus drive


Some time ago, a user posted the question about whether the MAXimus external hard disk, which is sold as a RAID-1 (mirrored) device, could be used for RAID-0.
See: http://forums.macrumors.com/archive/.../t-384106.html
I could not find any reference to this. Previous posts suggested using other products to achieve this.

The answer is below. Indeed, by changing the jumper configuration, it is possible to obtain all 4 RAID configurations that one can imagine with 2 separate disks.

What prompted this investigation for me is that the RAID-1 kept failing after copying files on the unit. So I wanted to access only one disk to test each one. Unplugging one disk seemed to do this, and I was convinced it is not the disk problem, and there didn't seem to be any problem in usage. But, can I access both disks?


Jumper configuration for: RAID-0 Striped, RAID-1 Mirrored, Concatenated Disk Set, Separate Disks

How to find the jumpers: with open unit, lights facing you (south), the fan facing away (north). The jumpers are at the NE (right side, away from you) end of the board.

RAID-1 - Mirrored (default)
:: Both jumpers not connected

RAID-0 - Striped
[:]: Left jumper on

Concatenated Disk Set
:[:] Right jumper on

Separate Disks
[:][:] Both jumpers on


Test methodology:
Read: sync; time (cp test.out > /dev/null) (ensuring the file is not in the cache)
Write: sync; time (dd if=/dev/zero of=blah3.out bs=1m count=1000 ; sync )
Write 1 GB
Monitor "Disk Activity" in Activity Monitor.App
Speed = 1 GB / time

Hard disks: 2X Seagate Barracuda 7200.11, 1 TB
Firewire 800

Results:

Raid 0:
Write speed: 49 MB/s
Read speed: 56 MB/s
Note: in test, both LEDs for HDD1 and HDD2 were on.

Raid 1:
Write speed: 62 MB/s
Read speed: 70 MB/s
Note: in test, both LEDs for HDD1 and HDD2 were on for write, only HDD1 for read.

Concatenated:
Write speed: 39 MB/s
Read speed: 50 MB/s
Note: in test, only LED for HDD1 was on.

Separate Disks:
Write speed: 62 MB/s
Read speed: 73 MB/s
Note: in test, only LED for HDD1 was on.

Separate Disks, Mac OSX software Striped:
Write speed: 48 MB/s
Read speed: 55 MB/s
Note: in test, both LEDs for HDD1 and HDD2 were on.

For reference, My MacBook Pro internal hard disk
Write speed: 59 MB/s
Read speed: 60 MB/s


Conclusion:

For highest performance, I will use "Separate Disks". Then I will do backups using ChronoSync. The RAID-1 was unreliable over the past year, and the individual disk will give me more confidence in data reliability.