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RAID Migration & RAID Expansion
Posted by - NA - on 17 October 2016 10:29

RAID Migration

Changing the number of disks or RAID level in current RAID configuration. The system will list the possible migration paths, and administrator can choose a possible path. For example, RAID 1 with 2 disks can be migrated to RAID 5 with 5 disks or RAID 5 with 3 disks can be migrated to RAID 5 with 4 disks.

RAID levels currently supported are : RAID 0, 1, 5.

The Migrate function is for change RAID Level or change RAID drive number, please refer below form

N4100PRO / N5200 / N7700 / N8800 RAID Migration

Firmware before 2.01.xx, offline migration available. During RAID migration, all services are not available.

RAID0 -> RAID0
RAID0 -> RAID5
RAID1 -> RAID0
RAID1 -> RAID5
RAID5 -> RAID5

Since firmware 2.01.08, we implement new "online migration", during migration, servers are still available.

RAID1 -> RAID5 
RAID1 -> RAID6 
RAID5 -> RAID5 
RAID6 -> RAID6

1U4200XXX / 1U4600 / N0503 / N3200XXX / N4100PRO / N4200 / N4200PRO / N4200ECO / N5200XXX / N5500 / N7700 / N7700SAS / N7700PLUS / N7700PRO / N8200XXX / N8800 / N8800SAS / N8800PLUS / N8800PRO

In newer firmware (32bit 3.xx , 32bit 5.xx), we remove the offline migration function and only online migration available.

RAID1 -> RAID5 
RAID1 -> RAID6 
RAID5 -> RAID5 
RAID6 -> RAID6

N4800 series / N5550 / N5810 series / N6850 / N7700PROV2 / N8800PROV2 / N8810U series / N8850 / N888U-10G / N8900 series / N10850 / N12000 series / N16000 series

In 64bit firmware, the migration option are available as following,

RAID1 -> RAID5 (Online) , require two more disks.
RAID1 -> RAID6 (Online) , require three more disks. 
RAID5 -> RAID5 (Online)
RAID5 -> RAID6 (Online), require add one or more disks.
RAID6 -> RAID6 (Online)
RAID50 -> RAID50 (Offline) (Migratable but RAID50 included with RAID0 thus unsupport expandsion)
RAID50 -> RAID60 (Offline) (Migratable but RAID60 included with RAID0 thus unsupport expandsion)
RAID60 -> RAID60 (Offline) (Migratable but RAID60 included with RAID0 thus unsupport expandsion)

RAID Expansion

When larger disks have replaced the smaller disks thru RAID Rebuild, the file system on the RAID is not changed. Administrator can press this button to check to see if there is room to expand the file system. If yes, then the file system will grow to take advantage of the larger disks.

And RAID Expand is for expand each drive maximum capacity, for example:

Drive #1 750GB
Drive #2 250GB
Drive #3 750GB

The RAID 5 total available capacity is 500GB. The behavior is the same as 250GB*3, therefore the RAID5 capacity is 500GB.

Note: During offline RAID Migration and RAID Expansion, all the file services such as SMB/CIFS, AFP, NFS, and FTP will not be available. The time to finish these operations depends on the size of your hard disk drives and your RAID volume..

WARNING: RAID Migration and Expansion are inherently risky operations. Please make sure your system is protected by an UPS (Uninterruptible Power Supply) to prevent accidental power failure, which might result data loss.

WARNING: These operations will cause heavy loading on your RAID system. RAID Migration and RAID Expansion will not be available if your RAID is in degraded state.

In case drive #2 250GB was replaced with 750GB drive, the NAS will begin rebuild RAID, after RAID rebuild is finished, the total capacity still 500GB , but once execute RAID Expand, the RAID total capacity will increase to 1.5TB.

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