Articles: Networking

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Basic Functionality

The NAS has two Gigabit Ethernet controllers that support Jumbo Frames up to 9000 bytes for higher performance. Besides working as two independent interfaces, they can work together to increase bandwidth or reliability. The network controllers support DHCP or can be assigned static IP addresses. The NAS offers integrated PPPoE and DDNS clients. A firewall is available to improve security on large networks. It allows to specify access rights flexibly for each interface. To make it easier, there is a predefined list with all the integrated services.

The user can also enable the feature that automatically blocks clients attempting to guess the password. That’s quite a useful option for a NAS, I think.

For each installed HDD you can learn the model name and firmware version. The NAS offers integrated tools to test and view the SMART info of each HDD. The power management system can turn the HDDs off if they remain idle for a certain period of time.

You can find an HDD compatibility list at the manufacturer’s website. It is rather long including the newest 2TB models. There is also another list that is based on users’ feedback. I do recommend you to check those lists out before choosing and purchasing HDDs for this NAS.

You can unite up to five HDDs installed in this NAS into RAID arrays. JBOD, RAID0, RAID1, RAID5 (also with a hot swap disk) and RAID6 are supported whereas RAID10 is missing. You can enlarge the maximum amount of disk space twofold by means of an external rack called Synology DX5. It can accommodate five HDDs which are connected via a single eSATA cable to the DS509+.

It is quite easy to manage data volumes. You can perform some configuration changes without losing your data. For example, you can migrate from one HDD to RAID1 or RAID5 or from RAID1 to RAID5. You can increase the volume size of a RAID5 or RAID6 array by sequentially replacing its HDDs with larger-capacity ones or by adding new HDDs.

A failure of an HDD in a fault-tolerant array provokes a log entry (and an email/SMS notification if enabled), appropriate indication on the front panel, and a sound signal (can be turned off in the web-interface). If there is a spare HDD (only for RAID5), the recovery process begins automatically. Otherwise, the user has to replace the disk and launch the process via the web-interface. It took about 2 hours and a half to recover a RAID5 built out of five 500GB HDDs after one of them had been replaced.

Besides typical RAID arrays, the new firmware also supports iSCSI. An iSCSI volume is created on an existing array and can thus be fault-tolerant, too.

The speed of iSCSI is usually somewhat higher because it is direct block-based access with lower overhead. However, I could only achieve read and write speeds of 45 and 47MBps, respectively, with a volume located on one disk. Data-transfer rates can be higher with RAID arrays.

To implement all these functionality, the system uses software RAID and LVM technologies. The main file system of data volumes is EXT3. Unfortunately, the manufacturer does not provide the option for the user to check the file system out manually and correct any errors. Perhaps the NAS is indeed so reliable, yet I would like to have that option anyway.

It is a distinguishing feature of Synology’s products that they support all modern file access protocols including SMB/CIFS, AFP, NFS, FTP(S) and HTTP(S). The NAS supports peer-to-peer mode and domains on Windows networks. A network trash bin for deleted files can be turned on.

As for AFP implementation, the NAS offers full support for TimeMachine, the Mac OS X integrated backup tool. This is a highly useful feature and many Apple users require it from their NASes.

There is nothing special about NFS. It just works and may be useful for users of network media players which provide higher video bit-rates via NFS than via SMB.

The FTP settings are almost perfect. You can change all the ports, limit the number and speed of connections, use Unicode, enable connection encryption, etc.

The capabilities of the browser-based file manager will be discussed shortly.

Traditional entities such as users, groups and shared folders are used to provide access to files. There are quite a lot of parameters you can specify for users: name, password, email address, comment, group membership, disk quota (individually for each disk volume). You can prohibit a user to change his password or block access on specific days. User groups are used for easier assignment of rights and do not have special parameters of their own.

Public folders are created on ready disk volumes. A few names are reserved for system services (e.g. “music”, “photo” and “video” for the media server). Access rights (no access, read-only, read & write) are assigned by users (for SMB, FTP and AFP) or by IP-addresses (for NFS). Special rights can be applied to folders and files for FTP and HTTP access: prohibition to view the list of files, prohibition to change existing files, and prohibition to download a file.

For NFS, you can create a list of hosts and address ranges with individual rights.

The NAS allows to control individual users’ access to specific services such as FTP, HTTP-based access, file download station, and video surveillance.

Summing it up, I must acknowledge that the NAS’s basic functionality is implemented very well. It is going to work correctly with any types of client devices.

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