[FAQ] The basics about RAID creation & data sync on QNAP NAS

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[FAQ] The basics about RAID creation & data sync on QNAP NAS

Post by QNAPJason » Tue Jul 21, 2009 5:48 pm

A. When an administrator creates a RAID volume, the system will create a RAID device and go through the following stages:
1. Creating the RAID device

2. Formatting the RAID device

3. Mounting it as a volume: After it’s mounted, the administrator can access the RAID volume and perform actions such as creating a share folder or uploading some files to a folder.

4. Synchronization: The percentage is shown on the Volume Management web page. You can still create a share when the RAID is syncing.

Note: For ensuring the stripes/blocks are ready in all RAID component devices, the RAID synchronization still needs to be completed.

B. Touch-N-Go: (on some models)
The percentage shown on the LCD screen includes Initializing HDDs, Creating the RAID device, Formatting the RAID device, and Mounting it as a volume.

Q1: 4x250GB in RAID5. If a drive is lost when the system is not fully synchronized, will I lose the data?
No, the RAID device will enter the “Degraded” mode. Your data is still accessible (Read & Write). After you replace the faulty HDD with a new HDD, then the RAID device will start to rebuild and return to the “Ready” mode.

Q2: How long does it take to fully synchronize my HDDs in RAID-1, RAID-5, and RAID-6?
There is no exact figure since the sync rate depends on HDD brand/model/spec. and other reasons such as occupied system resources when another volume is being accessed by other users. On average, the sync rate is around 30~60 MB/Sec.


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