QNAP Systems Ts 253 User Guide

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Configuring Spare Drives 
 
 
 
With this function, a spare drive can be added to or removed from a RAID 1, RAID, 5, RAID 6, or 
RAID 10 configuration. Unlike a global spare drive, the drive in this case will be dedicated to the RAID 
group. Follow these steps to configure a spare drive: 
1. Go to Storage Manager > STORAGE > Storage Space.  
2. Double click a storage pool to bring up the Storage Pool Management page. 
3. Select a RAID group and click Manage > Configure Spare Drive.    
4. Select the hard disk drive(s) to be configured as spare drive and click Apply. 
5. Please note that all data on the selected hard disk drive(s) will be erased. Click Yes if you are 
certain about this.        
6. The chosen disk drives are added as spare drive. 
 
Enabling/Disabling Bitmap 
 
This function can reduce the rebuild time after a crash, or the time length required to remove/re-add 
a hard disk. This feature does not improve disk read/write performance and may even cause slight 
performance degradation. However, if an array has a bitmap, a hard disk can be removed and 
re-added, and only changes in blocks need to be made since the removal (as recorded in the bitmap) 
can be re-synced. To enable a bitmap, follow these steps: 
1. Go to Storage Manager > STORAGE > Storage Space.  
2. Double click a storage pool to bring up the Storage Pool Management page. 
3. Select a RAID group and click Manage > Enable Bitmap and then OK.  
  
						

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To disable a bitmap,  
1. Go to Storage Manager > STORAGE > Storage Space.  
2. Double click a storage pool to bring up the Storage Pool Management page. 
3. Select a RAID group and click Manage > Disable Bitmap (only available after a bitmap has 
been enabled) and then OK. 
 
Note: Bitmap support is only available for RAID 1, RAID 5, RAID 6 and RAID 10. 
  
Recovering Failed RAID Disk Volumes 
 
This can recover failed RAID disk volumes from the Inactive status to a normal state (RAID 1, RAID 
5, RAID 6 and RAID 10 will be recovered to the degraded mode; RAID 0 and JBOD will be recovered 
to the normal state.) Before recovering a failed disk volume, please confirm that all hard disks of that 
disk volume are properly seated in the NAS drive bays. Once recovery is completed, immediately 
back up your data on the disk(s) in case the disk volume fails again. 
  
Inactive RAID disk volumes can only be recovered if the minimal number of healthy disks required for 
the RAID configuration is available on the NAS. For example, in a RAID 5 configuration with three 
disks in the array, at least two healthy hard disk drives are required available in the NAS for volume 
recovery. If not, this RAID volume cannot be recovered. Refer to the following table for the minimal 
number of hard disks required to recover a RAID group: 
RAID 
group 
Minimal number of hard disks required for recovery 
RAID 1 1 
RAID 5 Number of disks - 1 
RAID 6 Number of disks - 2 
RAID 10 Number of disks / 2; (1 hard drive per RAID 1) 
 
Follow these steps to recover a failed RAID group: 
1. Go to Storage Manager > STORAGE > Storage Space.  
2. Double click a storage pool to bring up the Storage Pool Management page. 
3. Select a failed RAID group. 
4. Click Manage > Recover. 
5. The chosen RAID group will be recovered. 
 
 
 
  
						

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Data Scrubbing 
 
Data Scrubbing scans the sectors of RAID groups and automatically attempts to repair failed sectors 
to maintain the consistency of the file system. This function is only supported by    RAID 5 and RAID 6 
and cannot be performed on a RAID Group that is in degraded mode. We recommend setting up a 
scheduled task for this function to avoid losing any critical data in the event of disk failure. Note that 
read/write performance may be affected during data scrubbing.  
						

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Cache Acceleration 
 
Based on SSD technology, the Cache Acceleration feature is designed to boost access performance of 
the NAS. On this page, you can both monitor SSD performance and manage cache acceleration for 
your NAS. This chapter covers the following topics: 
Feature Requirements 
Creating SSD Volumes 
Removing SSD Volumes 
Expanding SSD Volumes 
Configuring Volumes for SSD Cache 
 
Feature Requirements 
 
SSD drives must be installed to enable this function and this feature is only available for certain NAS 
models, with memory requirements. Refer to the following link for details:  
https://www.qnap.com/i/en/enterprise_apply_v2/con_show.php?op=showone&cid=7 
Refer to the table below for memory requirements: 
Cache Capacity RAM Requirement* 
512 GB from 1 GB to 4 GB 
1 TB from 4 GB to 8 GB 
2 TB from 8 GB to 16 GB 
4 TB Above 16 GB 
*For example, for 1 TB of SSD capacity, at least 4GB RAMs are required for the NAS. 
  
On this page, users can choose to create, remove and expand a SSD volume and configure the SSD 
cache. 
 
Note: You can toggle this feature by clicking the switch button right above Usage. 
  
Creating SSD Volumes 
  
Follow the steps below to create a SSD volume: 
1. Click Create. 
2. Select the SSD drive(s) and cache algorithm to create a SSD cache volume. 
3. Select the cache type: Read-Only or Read/Write. Click Next.  
						

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4. Choose the SSD Cache Mode: 
o Accelerate random I/O: Only small random I/O will be stored in SSD cache. This mode is 
recommended for virtualization and database applications. Also, select the bypass block size 
under this mode (block sizes that are larger than the specified one will not be cached).  
o Accelerate sequential I/O:    All I/O will be stored in SSD cache. This mode is recommended for 
video streaming or large file access operations.  
5. Select (or deselect) from the list to enable (or disable) the SSD cache for each iSCSI LUN and 
Volume.  
6. Click Create. 
7. Please note that all of the data on the selected hard drive(s) will be erased. Click OK to confirm. 
8. An SSD cache volume will be created. 
 
Note: If SSD Cache is enabled with the Read-Write type, the SSD MUST NOT be removed 
while it is being used, as this will cause data loss. 
 
   
Removing SSD Volumes 
  
Follow the steps below to remove a SSD volume: 
1. Click Remove. 
2. Please note that all data on the selected hard drive(s) will be erased. Click Yes if you are certain 
about this. 
3. The SSD volume will be removed. This operation can take a prolonged period if the SSD Cache is 
in Read/Write mode, as all the data in the cache must be flushed to the hard drive first. 
  
Expanding SSD Volumes 
  
Follow the steps below to expand a SSD volume: 
1. Click Add SSD Drive.    
2. Select the SSD drive(s) from the list and click Expand.    
3. Please note that all data on the selected hard drive(s) will be erased. Click Yes if you are certain 
about this. 
4. The SSD volume will be expanded. 
  
Configuring Volumes for SSD Cache 
  
Follow the steps below to configure volumes for a SSD cache: 
1. Click Cache Setting. 
2. Select or deselect a volume to enable/disable the SSD cache, choose whether or not to record 
large block, sequential I/O operations in the cache space, and click Finish.  
						

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3. The settings will be applied to the chosen volume. 
 
Note:  
For larger block, sequential I/O operations such as video streaming, the hit rate is 
lower, and by default, they are not recorded in the cache space. If you need to record 
such operations, please cancel this setting, but please remember that after this setting 
is cancelled, more cache space and computing resources will be consumed for such 
operations. 
Not all applications can benefit from a SSD cache. Please make sure that the SSD 
cache is supported by your applications.  
						

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Snapshot 
 
Snapshot Vault stores snapshots created remotely from remote NAS via Snapshot Replica in Backup 
Station. It also lets you manage and restore remote snapshots.  
 
 
In this chapter, the following topics are covered: 
Snapshot 
o Taking a Snapshot 
o Managing Snapshots with Snapshot Manager    
o Snapshot Global Settings 
o Managing Previous Versions in Windows 
Snapshot Vault 
o Filtering Snapshots 
o Displaying Snapshot Content 
o Removing Snapshots 
o Cloning Snapshots 
 
Note:  
Snapshot Replica (or volumes/LUNs replication between remote servers) is covered in 
Backup Station. For more details, please refer to the Snapshot Replica chapter in 
Backup Station.  
Snapshots and related features are currently only available for the following NAS 
series: x51*, x53, x63, x70, x71, x79, x80, x82, x89. 
o * The NAS must have minimum of 4 GB RAM to use snapshots.  
						

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o * x51 series models only support up to 256 snapshots instead of 1024. The HS-251 
does not support snapshots. 
 
Snapshot  
 
Taking a Snapshot 
After a reserved space is set, you can proceed to take snapshots. To create a snapshot, follow 
these steps: 
1. Go to Storage Manager > STORAGE > Snapshot.  
2. Switch between Volume or LUN depending on your needs, select a volume/LUN, and 
click Take a Snapshot.  
3. Specify the snapshot name, duration to retain the snapshot and snapshot type (the 
snapshot type is only available for LUN snapshots). 
4. Click OK.  
 
Managing Snapshots with Snapshot Manager   
To open Snapshot Manager, select a volume or LUN in Storage Space and click 
Snapshot > Snapshot Manager. Alternately, you can click the camera icon of a 
volume or LUN. 
  
Snapshot Manager enables you to perform the following actions: 
Action Description 
View snapshot details 
Select one of the following views: 
Table view: Displays a chronological list of all snapshots 
Timeline view: Displays a timeline containing all snapshots 
created within a specific period and other information, including 
the following: 
o Snapshot details: Name, date and time of creation, status, 
file size, and description 
o Volume details: Shared folders and files 
Restore and download files 
1.  Click a snapshot and select the folders and files that you want 
to restore. 
2.  Right-click one of the following: 
o Restore: Replaces the existing folder/file with the one in the 
snapshot 
o Restore to: Restores data to a different location 
o Download: Downloads the selection to your computer  
						

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Revert snapshots 
Select a snapshot and click Revert to restore the snapshot to its 
original path. 
Warning: The volume reverted to the selected snapshot will be in the previous state when 
the snapshot was taken. 
 
Clone snapshots to new 
volumes or LUNs 
1.  Select a snapshot and click Clone. 
2.  Type an alias for the new volume, and select the folders to 
share after cloning. 
Note: You can map cloned LUN snapshots to iSCSI targets. 
 
Delete snapshots Select a snapshot and click Delete to delete that snapshot. 
Configure snapshot schedules 
1.  Click Schedule. 
2.  Select Enable schedule and specify the time, frequency, and 
retention period. 
Note: For Smart Snapshot, the system takes a new snapshot only if new changes are 
made in the selected volume. 
 
 
Snapshot Global Settings 
There are two global snapshot settings: 
In the Snapshot Manager window: Click Snapshot global settings (the gear icon) in the 
top-right corner of the Snapshot Manager window. There is one global setting: 
Make snapshot directory (@Recently-Snapshot) visible: Mount a snapshot volume as a 
directory of a shared folder and set the snapshot volumes to be accessed (read-only) in 
File Station. The snapshot directory will appear as @Recently-Snapshot. 
In the Storage Manager window: Click Global Settings (the gear icon) in the top-right 
corner of the Storage Manager window, and there is one global setting: 
When reaching snapshot limitation: Choose the policy to handle snapshots when the 
snapshot limitation is reached. There are two choices.  
o Overwrite the oldest snapshot: When the number of snapshots reaches the limitation 
(256 per LUN, 1024 total) the oldest snapshot will be deleted in order to make space 
for new snapshots.  
o Stop making snapshot: When the number of snapshots reaches the limitation (256 per 
LUN, 1024 total), no more new and scheduled snapshots will be taken until existing 
snapshots are deleted. This option will prevent the deletion of older snapshots without 
administrators’ consent.  
 
Note: The When reaching snapshot limitation setting uses the number of snapshots, not 
the space used for snapshots. For more details, please refer to the Setting Snapshot  
						

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Reservation section. 
 
Managing Previous Versions in Windows 
Starting with QTS 4.2.1, snapshots can be used with the Previous Versions feature in 
Windows, allowing you to instantly revert to a previous version of a file in the event of an 
accident (e.g. file deletion, corruption, or accidental changes.) 
  
To use this feature, follow these steps: 
1. In Windows, connect to a shared folder on the NAS (the shared folder must be located in 
a storage pool where snapshots can be taken.) 
2. Take a snapshot of the storage pool where the shared folder is located. 
3. In Windows, right click on a shared folder (or a file in that shared folder) in File 
Explorer > Properties > Previous Versions. 
4. Select a version and choose to open, copy, or restore that version. 
5. Click OK.  
 
Note: This feature is only applicable to files that have been changed between snapshots. 
Otherwise, there will be no previous versions listed in File Explorer > Properties > 
Previous Versions.  
 
Snapshot Vault  
 
Snapshot Vault stores snapshots that are created by remote NAS devices and sent through 
Snapshot Replica in Backup Station. Snapshot Vault also allows you manage and restore 
remote snapshots, and replicate entire vaults to remote NAS devices.  
 
Note:  
If this is the first time using this feature, please configure Snapshot Replica in Backup 
Station on the source NAS first.    
Snapshots and related features are currently only available for the following NAS 
series: x51*, x53, x63, x70, x71, x79, x80, x82, x89. 
o * The NAS must have minimum of 4 GB RAM to use snapshots. 
o * x51 series models only support up to 256 snapshots instead of 1024. The HS-251 
does not support snapshots. 
 
Snapshot Vault enables you to perform the following actions: