Adding HDD on Array in ML350 G5 Server

[DigiOscar]

Sorry for my english,
I want to add third disk and upgrade array on ML 350 Server with E200I 128MB Battery-Backed Write Cache. Actually on server there are 2 72GB 10K SAS configured in RAID 1.
I have read that is possible to convert array in RAID 5 without loosing data, is correct ?
The problem is that I need to buy one disk identical to those installed.
Looking ACU information the 2 disk installed have this models: DG072A3515 and DG072ABAB3 ( I can't to remove disks for looking physical label ).
I have found available from my supplier 2 72GB 10K SAS disk: 375861-B21 and 384842-B21
which is correct to buy ?
Thanks

[TTr]

> ...convert array in RAID 5 without loosing data, is correct ?

Yes.

375861-B21: 73GB, 10kRPM Single Port
384842-B21: 73Gb, 10kRPM, Dual Port

The DG072ABAB3 is the SAS signature, the -B21 are part numbers. Both drives should work with the E200 controller but the specs for the server mention the second one 384842-B21 h18004.www1.hp.com/products/quickspecs/12475_div/12475_div.html

[MStoumba]

I have a number of these servers. How old are the drives? If a couple of years old which I think they are, then I would buy 3 146 gig drives , create new raid 5 and migrate old raid to new raid.

[DigiOscar]

The part number of server is: 470064-496 ( I have acquired it in 2007 and the disks were installed ).
If I have installed 2 single port disks and I add 1 dual port or viceversa, is a problem for migration in RAID 5 ?
thanks