Synology DiskStation Question

[maximus]

This is not a need to recover question, but a question about how easy or hard it would be to recover, and how the hybrid raid works, and also maybe if the hard drive activity lights are accurate. I have a Synology DiskStation DS418 that I configured for Synology Hybrid RAID (SHR). In theory it would be the equivalent of raid 5. But I notice that during data transfers, the lights for the drive activity are most active for only disk 3 and 4, leaning more heavy on 4. The size of the usage is currently low for the total size, so I just wonder if it is only really using only those two disks for the current storage. Can anyone explain what I am seeing? And also, since it is not standard raid, how easy or hard it would be to recover data from SHR, should the need ever arise, such as the unit failing?

[pcn]

Dear Maximus,

SHR is more complex than normal RAID. It consists of different RAID types connected as JBOD / LVM. So SHR is a RAID 5 (smallest drives) plus RAID 1 over the left space. If one drive from RAID 5 fails you still are fine. If one drive from RAID 1 fails you loose one part from RAID 5 and one part of RAID 1 and still are ok. If you add more storage the RAID 1 will be migrated to RAID 5, leaving a JBOD with two RAID 5.

Why only two LEDs show so much activity: I don't know, I would also expect more activity on other hdds.

Kind regards,

[maximus]

All four of the drives are the same size (and model), and it provides the usable space of a RAID 5. So then I would assume it is only working as RAID 5. Maybe then the activity of the lights is not accurate, because I would expect them to all show about the same activity.

Thanks for explaining the SHR, I wondered how that allowed for different size drives.