About

The NAS is called Dagda after the chief god of Irish mythology

Access

Dagda can only be accessed for the local TCD network at the following URL:

• abair.synology.me

This points to 134.226.90.69:5000

2FA

Two Factor Authentication is used for accessing the NAS over the local network.

Storage Pool

There is 1 storage pool named main ABAIR Pool which uses all the available HDD storage in RAID level 6.

This storage pool can be accessed in the UI in the Storage Manager application.

The total size is 36.4 TB

This consists of:

Drive ID	Drive Size
Drive 1	18.2TB
Drive 2	18.2TB
Drive 3	18.2TB
Drive 4	18.2TB

Data Scrubbing

Data scrubbing is scheduled to take place every 3 months.

Storage Volume

There is one storage volume called Main ABAIR Volume. Having one storage volume reduces the complexity of the setup and is suitable for small organisations like ABAIR.

Cache

There is a 1TB NVMe drive setup as a read cache

File System

The volume uses Btrfs, because it supports advanced features, including shared folder snapshots and replication, shared folder quota, and advanced data integrity protection.

Encryption

The whole volume is encrypted and the key is held by John and Andy. Linux Unified Key Setup (LUKS) is used to perform volume encryption. LUKS implements Advanced Encryption Standard (AES) in xts-plain64 mode,

What is AES?

AES (Advanced Encryption Standard) is a widely used symmetric encryption algorithm. It encrypts data using a secret key the same way for both encoding and decoding. AES is very strong, efficient, and is a standard for securing data worldwide. AES-256 is used on this system and is the most secure.

What is XTS-Plain64 mode?

When data is encrypted, it’s important to not just encrypt it but also organize how blocks of data are processed. That organization is called the mode of operation.

• XTS stands for XEX-based Tweaked CodeBook mode with ciphertext stealing. It’s a mode of operation designed specifically for encrypting data on storage devices like hard drives and SSDs—in other words, for encrypting data at rest.
• XTS mode enhances security when encrypting large amounts of data by preventing certain attacks that could happen if you use simpler modes (like ECB).
• The "Plain64" part refers to how the tweak value (a value that changes with each block to improve security) is calculated using the plaintext sector number encoded as a 64-bit number.

Shares

It is possible to create shared folders (shares) on the NAS and control who has access.

There are currently 2 shares available

1. recordings
2. MAO

The recordings share is encrypted and the key is held by John and Andy.

Data Checksums

Data checksums are used for advanced data integrity.

On Synology NAS, especially when using the Btrfs file system or enabling certain data integrity features on shared folders, checksums play an important role in protecting data:

1. Integrity Checking

Every time a file or data block is written to the disk, Synology generates a checksum for that data. Later, when reading the data back, it recalculates the checksum and compares it with the original checksum.

2. Detecting Corruption

If the checksums don’t match, it indicates the data might have been corrupted (due to disk errors, faulty RAM, or other storage issues).

3. Automatic Repair (with Btrfs)

If your volume is on Btrfs and you use RAID configurations that support redundancy (like RAID 1 or RAID 5/6), Synology can use checksums to detect corruption and automatically repair the damaged data by retrieving a good copy from another disk.

Groups

There are 5 user groups:

• administrators (system default)
• http (system default)
• users (system default)
• staff-read
• staff-read-write

staff-read

Can read all files

staff-read-write

Can read and write all files

Users

The following user accounts are active:

User	Groups
admin (system default)	staff-read-write
guest (system default)
andy	staff-read-write
sloanjo	staff-read-write
ailbhe	staff-read

TODO

Do Snapshot Replication and Hyper Backup Add UPS