QNAP Systems Ts 253 User Guide

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Station.  
The function or its content is only applicable on some models. To check for applicable 
models, please refer to the product comparison table on the QNAP website. 
o A minimum of 4 GB RAM is required to use snapshots. 
o x51 series models only support up to 256 snapshots instead of 1024. The HS-251 
does not support snapshots. 
 
Taking a Snapshot 
After reserved space is set, you can proceed to take snapshots. To create a snapshot, follow these 
steps: 
1. Go to Storage Manager > STORAGE > Storage Space.  
2. Select a volume or LUN and click Snapshot > Take a Snapshot.  
3. Specify the snapshot name and duration to retain the snapshot. 
4. Click OK.  
 
Managing Snapshots with Snapshot Manager    
The Snapshot Manager allows you to take, revert, delete, and clone a snapshot, set up snapshot 
schedules, or restore snapshot files.  
To launch Snapshot Manager, select a volume or LUN in Storage Space and click Snapshot > 
Snapshot Manager (or click the camera icon of a volume or LUN.) 
In Snapshot Manager, you can perform the following actions: 
Restore files: Click a desired snapshot and select the folder(s) or file(s) that you want to restore, 
right click and select Restore to replace the existing folder/file with the one in the snapshot or 
Restore to to restore your data to a different location. Or choose Download to download the 
selection to your computer. 
Revert a snapshot: Select a snapshot and click Revert, and the entire snapshot will be restored 
to its original path. Be cautious that the volume reverted to the selected snapshot will be in the 
previous state when the snapshot was taken. 
Delete: Select a snapshot and click Delete to delete that snapshot. 
Clone a snapshot: This action allows you to clone a snapshot into a new volume or LUN.    To clone 
a snapshot, first select a snapshot, click Clone, enter an alias for the new volume, and select the 
folders to share after cloning. If the snapshot cloned is a LUN snapshot, you can map it to an 
iSCSI target. 
Set up snapshot schedules: Click Schedule, select Enable schedule, specify the time, 
frequency, and retention period. The system will take the chosen volume’s snapshot by schedule. 
For Smart Snapshot, the system will only take a new snapshot if there are new changes made in 
the selected volume.  
 
 
  
						

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Snapshot Global Settings 
Click Global Settings in the top-right of the Snapshot Manager window, and 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 read-only in File Station. The snapshot 
directory will appear as @Recently-Snapshot. 
 
Click Global Settings in the top-right 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 continue taking new snapshots 
for data protection.  
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 older snapshot 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 
Reservation section. 
 
Managing Previous Versions in Windows 
 
Starting in 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 case 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 that you can take a snapshot.) 
2. Take a snapshot of the storage pool where the shared folder is located. 
3. In Windows, right click on the 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.  
						

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Otherwise, there will be no previous versions listed in File Explorer > Properties > 
Previous Versions.  
 
 
Encryption 
 
The disk volumes on the NAS can be encrypted with 256-bit AES encryption to protect against data 
breaches. Encrypted disk volumes can only be mounted for normal read/write access with an 
authorized password. The encryption feature protects confidential data from unauthorized access 
even if the hard drives or the entire NAS were stolen. 
 
Note: The AES volume-based encryption is applicable only to specific NAS models. Please 
refer to the product comparison table for details.  
 
Data encryption on QNAP NAS 
Users can manage encrypted disk volumes on the NAS. Each encrypted disk volume is locked by a 
particular key. The encrypted volume can be unlocked using the following methods: 
Encryption password: Enter the encryption password to unlock the disk volume. The password 
must be 8-32 characters long. Symbols (! @ # $ % ^ & * ( )_+ = ? ) are supported. 
Encryption key file: Upload the encryption key file to the NAS to unlock the disk volume. The key 
can be downloaded from the Encryption page after the disk volume is successfully unlocked. 
 
Before you start 
Please remember the following before using the data encryption feature of the NAS. 
The volume encryption feature of the NAS is volume-based. A volume can be a single disk a JBOD 
configuration, or a RAID array. To only encrypt a shared folder, please refer to the Shared Folder 
chapter. 
Select whether or not to encrypt a disk volume before it is created on the NAS. A volume cannot 
be encrypted after it is created unless the disk volume is initialized. Note that initializing a disk 
volume will clear all data on the disks. 
Disk volume encryption cannot be removed without initialization. To remove encryption on the 
disk volume, the disk volume must be initialized and all the data will be cleared. 
Keep the encryption password or key safe. If the password is forgotten or the encryption key is 
lost, the data cannot be accessed and cannot be recovered. 
Before starting, read the instructions carefully and strictly adhere to them. 
 
Note: Data encryption functions may be unavailable in accordance to the legislative 
restrictions of some countries (ex. Russia, Belarus, Ukraine, Kazakhstan and Uzbekistan.)  
  
						

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Creating new encrypted disk volumes 
1. Log into the NAS as an administrator. Go to Storage Manager > STORAGE > Storage Space 
and click Create > New Volume. 
2. Select a volume type based on your needs and click Next.  
3. Specify the volume details (including the volume capacity, alert threshold and volume alias,) tick 
Encryption, fill out the encryption password and choose whether to save the encryption key, 
select to create a shared folder automatically after new volume initialization and fill out the name 
of the shared folder for the intended volume. Click Next. 
4. Confirm the settings and click Finish. 
5. Note that all the data on the selected drives will be DELETED! Please back up the data before 
creating the encrypted volume. Click Yes after data backup. 
6. Double click the newly-created volume to bring up the Volume Management page. 
7. Click Actions > Encryption > Lock this Volume. Click Yes. 
8. An encrypted disk volume will be created on the NAS. 
 
Encryption key management 
To manage the encryption key settings, log into the NAS as an administrator and go to Storage 
Manager > STORAGE > Storage Space. Double click a volume to bring up the Volume 
Management page and click Actions > Encryption. 
There are three options to manage the encryption key: 
Change the encryption key: Enter your old encryption password and the new password. (Please 
note that after the password is changed, any previously exported keys will not work anymore. The 
new encryption key needs to be downloaded if necessary, see below.) 
Download the encryption key file: Enter the encryption password to download the encryption key 
file. With this option, the encryption key can be saved as a file. The file is also encrypted and can 
be used to unlock a volume, without knowing the real password (see Locking and unlocking disk 
volumes manually below.) Please save the encryption key file in a secure place! 
Save the encryption key: Save the encryption key on the NAS to automatically unlock and mount 
the encrypted disk volume after the NAS restarts. Note that saving the encryption key alone 
is not completely safe, as if the NAS is stolen, the volume will be automatically unlocked 
after it restarts.   
 
Locking and unlocking disk volumes manually 
To lock a volume, log into the NAS as an administrator. Go to Storage Manager > STORAGE > 
Storage Space. Double click a volume to be locked to bring up the Volume Management page and 
click Actions > Encryption > Lock this Volume. Click Yes.  
  
						

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To unlock a volume, log into the NAS as an administrator. Go to Storage Manager > STORAGE > 
Storage Space. Select a volume to be unlocked and click Manage >  Unlock this volume. Choose 
either to enter the encryption password, or use the encryption key file exported previously. Click 
Apply. If the encryption password or the key file is correct, the volume will be unlocked and become 
available. 
 
 
 
Verifying encrypted disk volumes 
To verify that a disk volume is encrypted, log into the NAS as an administrator. Go to Storage 
Manager > STORAGE > Storage Space. The encrypted disk volume will be shown on this page, 
with a lock icon under Status. The lock will be shown as opened if the encrypted volume is unlocked. 
A disk volume without the lock icon under Status is not encrypted. 
 
Behaviors of encrypted volumes upon system reboot 
An example is provided to illustrate the behavior of encrypted volumes upon system reboot. In this 
example, there are two encrypted disk volumes on the NAS: 
DataVol1 is created with the option Save Encryption Key disabled. 
DataVol2 is created with the option Save Encryption Key enabled. 
 
Note: For details on enabling or disabling the Save Encryption Key option, please refer 
to the section on Encryption Key Management above. 
 
After restarting the NAS, check the volume status. DataVol1 is locked, but DataVol2 is unlocked and 
mounted. Since the encryption key is not saved on DataVol1, the encryption password needs to be 
manually entered to unlock DataVol1. Please remember that by saving the key on the NAS, data will 
only be protected in case of stolen hard disk drives. However, there is still a risk of data breach if the 
entire NAS is stolen as the data is    accessible after the NAS is restarted. If the encryption key is not 
saved on the NAS, the NAS will be protected against data breach even if the entire NAS were stolen. 
The disadvantage is that the disk volume needs to be manually unlocked each time the system 
restarts. 
  
Setting Thin Provisioning Space Reclamation and SSD Trim  
  
Thin Provisioning Space Reclamation allows you to increase free space on thin-provisioned storage 
pools by reclaiming space from deleted files. SSD Trim enables garbage collection on SSDs, which 
wipes out blocks of data that are no longer in use, and increases future write performance. 
  
						

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To enable Space Reclamation and SSD Trim, log into QTS, launch Storage Manager and click on the 
Global Settings icon located at the top right of the Storage Manager window. The Global Settings 
window will open, then click on Edit beside Space Reclamation and SSD Trim. There are two 
settings for Space Reclamation and SSD Trim: 
Auto reclaim and SSD trim schedule: Check this checkbox to enable space reclamation and 
SSD trim. 
Schedule: Set the schedule for thin provisioning space reclamation and SSD TRIM in order to 
reclaim space and increase free space for storage pools.  
						

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RAID Groups 
 
Users can expand a RAID group, add hard drive(s) to a RAID group, migrate a RAID group, configure a 
spare drive, enable a bitmap and recover a RAID group for a chosen volume, while the data contained 
in the RAID group remains intact. In this chapter, the following topics are covered: 
RAID Group Introduction 
Expanding RAID Group Capacity 
Adding Hard Disk Drives 
Migrating RAID Configuration 
Configuring Spare Drives 
Enabling/Disabling Bitmap 
Recovering Failed RAID Disk Volumes 
Data Scrubbing 
 
RAID Group Introduction 
 
RAID group types 
Refer to the table below for explanations on RAID types: 
Field Description 
Single Disk A single, stand-alone RAID group can be set up for your NAS. However, this setup 
does not provide any redundancy protection. So, in the event that a disk is 
corrupted or otherwise damaged, all data on that disk will be lost. 
RAID 0 
Striping 
A striping RAID group combines two or more disks into one large, logical disk. It 
offers the fastest disk access performance but no data redundancy protection in the 
event of disk failure or damage. The disk capacity is the sum of all disks. Disk 
striping is usually used to maximize disk capacity or to accelerate disk access 
speed. Please note that RAID 0 configuration is not recommended for storing 
sensitive data. 
RAID 1 
Mirroring 
Disk Mirroring protects your data by automatically mirroring the contents of one 
disk to the second disk in the mirrored pair. It provides protection in the event of a 
single disk failure. The storage capacity is equal to the capacity of the smallest 
single disk, as the second disk drive is used to back up the first disk drive. RAID 1 
configuration is suitable for storing sensitive data on a corporate or personal level. 
RAID 5 RAID 5 configurations are ideal for organizations running databases and other  
						

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transaction-based applications that require storage efficiency and data protection. 
A minimum of 3 hard disks are required to create a RAID 5 group. The total 
capacity of the RAID 5 group is equal to the size of the disk with the smallest 
capacity in the array times the number of (hard disk – 1). It is recommended 
(though not required) that only hard drives of the same brand and capacity are 
used to establish the most efficient hard drive capacity. 
 
In addition, if your system contains four disk drives, it is possible to use three 
drives to implement a RAID 5 data array with the fourth drive kept as a spare disk. 
In this configuration, the system will automatically use the spare disk to rebuild the 
array in the event of a physical disk failure. A RAID 5 configuration can survive one 
disk failure without losing any system functionality. When a disk fails in RAID 5, the 
disk volume will operate in the degraded mode. There is no more data protection 
at this stage, and all the data will be lost if the unit suffers a second disk failure. A 
failed disk should be immediately replaced. Users can choose to install a new disk 
after turning off the server or hot-swap the new disk while the server is running. 
The status of the disk volume will change to rebuilding after installing a new disk. 
Your disk volume will return to a normal status once the volume rebuilding process 
is complete. 
  
Note: To install a new disk when the server is running, first ensure the disk volume 
is in degraded mode. Or, wait to hear two long beeps after the disk crashes and 
then insert the new disk in place of the failed disk. 
RAID 6 RAID 6 is ideal for critical data protection needs. To create a RAID 6 group, a 
minimum of 4 hard disks are required. The total capacity of a RAID 6 group is 
equal to the size of the disk with the smallest capacity in the array times the 
number of (hard disks – 2). It is recommended (though not required) to use 
identical hard drives to establish the most efficient hard drive capacity. RAID 6 can 
survive 2 disk failures and the system can still operate properly. 
  
Note: To install a new disk when the server is running, first ensure the disk 
volume is in degraded mode. Or, wait to hear two long beeps after the disk crash 
and then insert the new disk in place of the failed disk. 
RAID 10 RAID 10 is a combination of RAID 1 (mirroring) and RAID 0 (striping), without 
parity. RAID 10 is a stripe across a number of disks to provide fault tolerance and 
high speed data transfer. The storage capacity of a RAID 10 group is equal to the 
size of the disk with the smallest capacity in the array times (the number of hard 
disks in the array/2). It is recommended that only hard disk drives of the same  
						

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brand and capacity are used to create a RAID 10 group. RAID 10 is suitable for 
high volume transaction applications, such as a database, that require high 
performance and fault tolerance. A maximum of 1 failed disk from each disk pair is 
allowed in RAID 10. 
  
Note: To install a new disk when the server is running, first be sure the disk 
volume is in the degraded mode. Or, wait to hear two long beeps after the disk 
crashes and then insert the new disk in place of the failed disk. 
JBOD Two or more disks can be combined into one larger volume. Files are sequentially 
saved on physical disks. The overall capacity of the linear disk is the sum of the 
capacity of all disks. This configuration does not provide disk failure protection; 
failure of one drive will cause the entire array to be lost. A JBOD group is generally 
used for storing a large amount of data. It is not appropriate for storing sensitive 
data. 
 
Bad Block Management (BBM) 
BBM uses the bad block list (log) for each drive and uses it to allow the system to fail single blocks 
rather than entire drives. This feature is especially useful for RAID arrays and is automatically 
enabled if your disks support BBM. Bad blocks in different sections on different drives can cause a 
RAID array to fail. With BBM, the RAID array can be functional even when encountering bad blocks. 
 
Note: BBM support is only available for RAID 5 and RAID 6. 
  
Expanding RAID Group Capacity 
  
With this function, RAID group capacity can be expanded by replacing hard disk drives in a RAID 
group array one by one. This option is supported for the following RAID types: RAID 1, RAID 5, RAID 
6 and RAID 10. Follow these steps to expand a 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 RAID group and click Manage > Replace Disks One by One. 
4. Select at least one hard disk drive. After the description displays Please remove this drive, 
remove the hard disk drive from the NAS or expansion enclosure.        
5. After the description displays You can replace this drive, plug in the new hard disk drive to the 
drive slot. Repeat the same process for all hard drives to be replaced. Click Expand Capacity to 
continue.    
6. Click Yes.        
7. The chosen RAID group is expanded. 
   
						

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Adding Hard Disk Drives 
  
With this function, new drive members can be added to a RAID group. This option is supported for 
RAID 5 and RAID 6 drive configurations. 
Follow these steps to add the hard disk drive(s) to a 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 RAID group and click Manage > Add Hard Drive.    
4. Select hard disk drive(s) from the list to add to the chosen RAID group and click Apply.        
5. Please note that all data on the selected hard drive(s) will be erased. Click Yes if you are certain 
about this.    
6. The chosen hard disk drive(s) are added to the selected RAID group. 
 
Note: New disks cannot be inserted into existing RAID groups for specific RAID types, 
such as, RAID 0, RAID 10, Single, or JBOD. You must create additional RAID groups to 
expand these storage pools. 
  
Migrating RAID Configuration 
 
With this function, a RAID configuration can be migrated to a different RAID configuration. This option 
is supported for the following drive configurations: Migrating single drives to RAID 1; Migrating RAID 
1 to RAID 5; Migrating RAID 5 to RAID 6. Follow these steps to migrate a RAID configuration: 
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 > Migrate.    
4. Select the hard disk drive(s) from the list 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 RAID configuration is migrated to the new one.