How to change RAID level without data loss?

Question

RAID

There is:

• Storage IBM DS3512 with two controllers

• Expansion shelf EXP3512

• Two x3250M4 servers, each with two HBA adapters on board

Storadzh completely clogged with disks, 3TB each. Servers are included according to the fault-tolerant scheme.

The configuration has 4 RAID5 arrays, each with one logical partition. 1 partition mapped to the first server, 3 to another.
Now the task is to change the configuration and make one out of 3 sections. By changing the RAID level to acceptable for such a task. Ideally, make a pool and map it to the second server. Do not touch the first array.
Question: how to do without data loss?

Answer 1

1. Connect another storage.
2. Transfer the DATE to it.
3. Do what you like with the old storage.

Answer 2

Backup, rebuilding arrays, restoring from backups.
In general, two backups are better, since during such operations the risks of losing data increase greatly