Server 101: SAN and NAS

Storage is one of the topics that is done differently in the corporate world than home environment. In SOHO data is usually stored in directly attached hard drives and in a device in a device over the network using a NAS. On the other side, corporate usually depend on something called a SAN to store their corporate data.

NAS?

Image of a NAS
Synology DS1511+ NAS – Courtesy of Synology

 

NAS stands for Network Attached Storage, which is basically generally a device over the network that is used to host and share information over the network. The device can serve multiple services or dedicated for file storage.

NAS is a file level storage. File level storage mean that the NAS and the client exchange files between them over the network, just like when a file download from a website. Moreover, with file level storage files are usually stored in a fixed location with a fixed storage capacity. As a result, expanding storage capacity is usually not possible and always require some downtime.

There are many protocols used for files storage such as SMB and AFP. Most NAS devices nowadays support and use SMB as its main file exchange protocol.

SAN?

 

A picture of a SAN Component
emc VNXe1600 SAN – Courtesy of EMC

SAN stands for Storage Area Network and it is a network of multiple devices connected to serve a single purpose …storage. The network contains fiber matrix, storage controller and even pools of blazing fast hard drives.

Unlike NAS, SAN uses block level storage. In a nutshell, block level storage means that communication between the SAN and the client is treated like a directly attached hard drive into a motherboard. As a result, SAN mounts are visible as a local hard drive on clients.

There are two main protocols for SAN: iSCSI (Internet Small Computer Systems Interface) and FC (Fibre Channel). Most SAN nowadays use FC is built specifically for SAN and it is faster than iSCSI, but it is more expensive.

Why SAN over NAS?

Large enterprises use SAN over NAS for multiple reasons. First, SAN performance is higher than most NAS devices, due to the way storage area networks are built. Second, SAN allow easily to modify storage allocation of each storage mount. Also, the mount can reside on single hard drive, single virtual hard drive and event on two different building! Third, Storage are networks are real fault tolerant if built correctly. HP has proofed that a SAN can be bullet proof literally in an old TV commercial!!! The commercial can be viewed bellow.

 

Hemo’s Take

It is alright if you are not very familiar with SAN, as it is considered as big boys toys. Myself, I don’t have the permission to work with it yet, but one day both of us will work with it 😊

Server 101: 3 2 1 Backup

3 2 1 Backup Srategy illustrative yet unimportant image
Coutesy of BackBlaze

In May 2017, a massive cyber-attack caused by WannaCry ransomware. Such attack has increased the awareness of the importance of backups. However, many system administrator, especially novice ones faced the consequences of   improper backup strategies that are never tested. Such strategies mostly lead into a huge chunk of missing or useless data. Fortunately, there are  a set of recommended tested strategies that insure no data loss as much as possible. One of these strategies is what is known as 3-2-1 Strategy Back up.

 

The number three means that each file must be three copies of each file. Moreover, it also means that all files are identical and have exact check sum value. Check summing is a calculation done using certain algorithms, that ensures integrity of data were not changed after sending them into a medium.

3-2-1 Backup

Three copies are recommended instead of three, because in some scenarios even the backup files might fail. An example of such scenarios is when a system is hit with a malware that encrypt all files attached. Different media is recommended because each medium has a different

Second, number 2 means these copies are save in at least two different back up media. These media could be a conventional hard disk drive, a tape, or even an optical disk such as DVD or Blu-ray. Moreover, cloud storage can be considered as a media, even though it uses one of the previously mentioned media.

Last, number 1 means that at least one copy must be offsite. It is advised that the offsite location is at least 25 KM away from the original copy. Offsite copies are critical when original location was affected by a catastrophic incident such as a flood, fire and earth quakes. Moreover, physical security should be implemented and assured when offsite location is run and manage by corporate itself.

Hemo’s Take

No matter how many copies do you have of a file if these copies are not identical and corrupted. Thus, after ensuring that files are copied as mentioned above, ensure that are the identical and retrievable every six months. You really do not want to get back to a backup and nothing is there.

Server 101: RAID under the scope

Fault tolerance is one of the concepts that is put into consideration when designing an infrastructure. In a nutshell fault tolerance is the ability for a device or a system to operate, even when it is faulty. One of the technologies that is based on the concept is fault tolerance is RAID.

What is RAID?

RAID which stands for Redundant Array of Independent Drives is technology that allow multiple hard disk drives to work as a single entity. As a result, characteristics of these hard drives change based on its levels up used and it is mostly implemented in servers. There are multiple setups exists, but in this post, the main three RAID levels will be covered. The main three levels are level 0, level 1 and level 5.

RAID 0

RAID 0
Data distribution in RAID 0 (Courtesy of Wikimedia)

RAID level 0 or known as RAID zero or striping is a set up consists of two or more hard drives, where data is spit across all hard drives as seen in the picture above. Such setup allows data to be read and written times faster than the specs of each hard drive. However, in case of disk failure or data corruption in a hard drive, all data will be about useless.

RAID 1

Data Distribution in RAID 1
Data Distribution in RAID 1 (Courtesy of Wikimedia)

RAID level 1 or known as mirroring or RAID 1 is a setup consists of two or more hard drives, where data is duplicated across all hard drives. As a result, data remain safe if a one hard drive is intact. On the other side, RAID 1 has its share of disadvantages. First, despite the amount of hard drives are added to the setup, only the capacity of the smallest hard drive will be used.  Second, RAID 1 doesn’t provide any additional performance than standalone hard drive.

RAID 5

Data Distribution in RAID 5
Data Distribution in RAID 5 ( Courtesy of Wikimedia)

RAID 5 that is also known as Striping with distributed sets is a setup consists of three or more hard drives. Unlike other levels, RAID 5 mechanism saves the piece of data on a hard drive and keep certain calculations on others and these calculations enable data to be recovered. Due to its mechanism RAID 5 provides continuous operation, even with a failed drive in the pool. Moreover, these calculations can lead toward a faster operation.

Hemo’s Take

RAID is a fun topic to discuss. IT pros can argue which RAID is the best RAID. Also, another argument can take place regards software based RAID versus dedicated RAID controller based RAID setup. Other storage experts might argue that RAID 5 should not be used and RAID 6 should be used instead. To be honest, what really matter is to know why and where use to use each RAID level. What matters is which RAID level is the most beneficial and most suitable for the requirements.

Server 101: Server Rack Components

A lot of equipment is installed in server racks besides servers. These server devices serve different purposes such as cable management and energy supply. In this post, we will discover these devices and learn more about them and why are they used.

PDU

Front Side of a PDU
-Courtesy of gdftech

In short, PDU which stands for power distribution unit is an expensive power strip on steroid. So, it can be defined as a special type of power strips that distributes electricity to server and other devices. Moreover, they are designed to be efficient, safe and able to distribute sufficient energy to all server racks. PDUs excel when multiple three-phase power sources are used together to power server rack equipment.

UPS

Rack Mounted UPS (Courtesy of Eaton)
Rack Mounted UPS (Courtesy of Eaton)

UPS which stands for Uninterrupted Power Supply is a device that either placed in a server rack or in a separate location and it is serves two purposes. First, it contains a battery pack that feeds server room equipment during a power outage for a finite time and prevents any data corruption due to power outage. Second, Uninterrupted Power Supplies cleans the electricity that feeds the devices. As a result, devices will work better and prevent power related faults. Modern smart UPSs are capable to notify system administrators about power outages and shut down devics safely when the batter is out to run out of charge.

KVM Switch

USB Based KVM Switch
USB Based KVM Switch (Courtesy of D-Link)

KVM (Keyboard, video, Mouse) switch or known as KVM for short is a device that is used to allow a single mouse, keyboard and monitor screen to be used by multiple computers. Thus, less peripheral device in the server room, especially that most device are rarely accessed directly.

KVM can connect to devices in two different methods. First method is by using a USB and a video cables (VGA, HDMI or DVI) between each device and the KVM. The second method that is usually used by the higher end KVM switches is by depending on IP protocols to connect between the KVM and the devices i.e. using the current network infrastructure to connect remote machines to the KVM switch.

Patch Panel

Front and Read View of a Patch Panel
Front and Read View of a Patch Panel

One of the main concepts in network cable management is decoupling. Decoupling means in this case is separating between access switches and end device, by adding a patch device in between. Adding a patch panel helps network and system administrators to reassign network cables between different network devices easily.

Patch panels consist of two sides. First, the rear side which is used to connect between the end machines and the patch panel. Second, the front side which is used to connect between patch panels are network devices.

Hemo’s Take

In real life, server racks have more equipment than mentioned here such as NAS, Tape drives and even GPS-based NTP servers. However, these devices the most important and about no proper server rack is without them.

 

Server 101: Shapes of servers

Servers come in different shapes. Today their shapes will be looked and discussed.

What shapes do you take Mr. Server??

Servers can take three main shapes: tower, blade and rack mount. Servers come in shapes for multiple reasons such as cost, power efficiency and noise.

Rack Mount:

shape of rack mount server.
Courtesy of Dell Inc.

Rack mounted shape is most conventional shape servers comes in and it allows data center technicians to stack 3-4 physical servers  on top of each other in a server rack. It is more seen in the small to medium businesses that require multiple servers but no more than five. However, rack mounted servers are generally more expensive than other tower servers and it is noisier than tower ones.

Tower:

Tower server shape
Courtesy of Dell Inc.

Tower shape is similar to desktop computer (Technically speaking our personal computers are not desktop computers, because desktop ones are the one that sit on top of desks like the old whitish ones). Small businesses tend to pick this shape over others, because it is more cost effective than others, especially if these businesses need one or two for all their operations. Thus, shape is recommended for them. Unlike most shapes, tower servers allow adding multiple regular 3.5 hard disk drives, that are more expensive. On the other side it takes more space than others.

 

Blade Servers:

A picture of a Blade Server
Courtesy of Hewlett Packard Enterprise

Blade shape  or blade servers are a form factor developed by IBM to create modular and efficient design that allow them stack as much physical servers as possible within a single server rack. Each module is called a blade. Despite its modular and efficient design, blade servers has its share of cons. These servers need high RPM fans, as a result they are noisy. Also, due to its compact size, ability to add expansion card is limited. Third, it is more expensive than others, with the same hardware inside.

Hemo’s Take

Recently, other forms are seen in server room. In home server rooms, laptops are used for its size, price and usage of laptop battery as a ghetto USP. In addition to laptops, System on Chips such as Raspberry Pi is implemented.

Server 101: What is a server

Tech workers spend most of their time either in server rooms or near them. However, not all of them know the ins and outs of server rooms. In this series server rooms will be discussed here. So, this topic will start with the most obvious question.

Group of server cabinets
Courtesy of ipzonecomputer

What is Server?

Many people think that servers are large, loud, expensive and hard to use machines. However, they thoughts are not true.  The definition of server is any device that provide any type of services to other machines on the same network and other network, because the term server is assigned to machines based on its relation to a certain service.

As a result, we see different types of “Computers” act as a server. We started to see microcomputers such as Raspberry Pis, and atom based computers act as server for clients who are waaay more powerful, more expensive and more difficult to use computers.

Servers serve different types of services. These services varies from serving a group of files to a different to managing user authentication and logging, to managing prints over a network. According to the service provided, system administrator choose the type of hardware that will serve the purpose and consume the least amount of power.

Hemo’s Take

Do not look at servers are as magical, difficult, expensive machines that working on them are rocket science. They are just like the machines that  we use at home, but with small  differences. Dealing with servers are just a nice journey into getting better at your job.

In the end remember, we the tech workers are supermen who do not wear  tight clothes 🙂