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QTS 5.0.x

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RAID Bitmaps

If a disk is temporarily disconnected from its RAID group and then reconnected, the RAID group must synchronize all of its data. This process may take a long time. If the RAID group has a bitmap then only changes that were made after the disk was disconnected need to be synchronized, greatly speeding up the process.

A disk can become temporarily disconnected in the following situations.

  • A disk is accidentally removed from the NAS while the NAS is powered on.

  • The NAS unexpectedly shuts down because of a hardware or software error.

  • A user presses the power button for 10 seconds or disconnects the power cable while the NAS is powered on.

  • You can only create bitmaps for RAID 1, RAID 5, RAID 6, and RAID 10 groups.

  • Enabling a RAID bitmap may slightly decrease the read and write performance of the RAID group.

  • A bitmap improves synchronization time only if the same disk is disconnected then reconnected. Having a bitmap does not improve synchronization time when a new disk is added to the RAID group.

Creating a RAID Bitmap

  1. Go to Storage & Snapshots > Storage > Storage/Snapshots.
  2. Select a storage pool or single static volume.
  3. Click Manage.
  4. Select a RAID 1, RAID 5, RAID 6, or RAID 10 group.
  5. Select Manage > Enable Bitmap.

    A confirmation message appears.

QTS creates a bitmap for the RAID group.