SAN (storage area network) is a high-speed network of storage devices that also connects those storage devices with servers. It provides block-level storage that can be accessed by the applications running on any networked servers. SAN storage devices can include tape libraries and disk-based devices, like RAID hardware.
Here are a few advantages of SAN:
Scalability
SAN has many advantages over DAS in your data center. Here are 10 reasons to consider making the leap from local storage to a SAN.
If you know, or have heard, one thing about a SAN, it's scalable. What does scalable mean? SAN scalability means that you don't have the limit of a handful of disks that you can attach to a system. SANs can grow to hundreds of disks in size, whereas your server has a physical limit of about a dozen.
2. Performance
SAN performance isn't affected by Ethernet traffic or local disk throughput bottlenecks. Data transmitted to and from a SAN is on its own private network partitioned off from user traffic, backup traffic and other SAN traffic.
3. Data Isolation
There's no chance of your data being copied or stolen by anyone sharing the same SAN with you. Not even the SAN admins can see your data. When correctly configured, SAN data is zoned. These zones protect your data from everyone else's on the same SAN. An example of SAN zone separation is how UNIX servers can connect to a SAN and Windows servers connect to the same SAN, but the data that each group of servers accesses is different. In effect, Windows systems can't "see" UNIX data and vice versa.
4. Uptime
There's nothing quite like a SAN to assure 100-percent storage availability. SAN systems require no reboots to add new disks, to replace disks or to configure RAID groups. The ability to stream data between SANs for data backup and recovery also increases performance by bypassing server systems completely.
5. Workload Isolation
Zoning also separates your workloads from one another on a SAN. Not only is your data protected by zoning, but it also provides a barrier against other non-related workloads from affecting your application's performance. Sharing a SAN isn't a performance problem for applications when zones are in place.
Long Distance Connectivity
SANs have the advantage over all other storage connectivity for distance at 10km (about 6 miles). Not that you'll necessarily use that distance capability, but it's there if you need it. Having the advantage of distance allows you to consolidate your storage into an isolated location dedicated to storage and separate from the systems it serves.
7. Increased Utilization
Rather than hundreds or thousands of partially utilized local disks wasting power and generating heat in your data center, you could have dozens of SAN disks have no wasted space on them. How so? Thin provisioning on the storage side (i.e., on the SAN) uses space more effectively than local storage does. As a system requires more storage, the SAN allocates it dynamically. Yes, this means that physical systems can enjoy thin provisioning just like your virtual ones do.
8. Bootable
Despite the benefit of more fully utilized disks, as highlighted in advantage No. 7, you do not need to use local disks for the server operating system. It's possible to run diskless physical servers and boot directly to the SAN for your operating system, swap space (pagefile), and all applications. That's right, just like virtual machines.
9. Centralized Management
If you have SAN arrays from several different vendors because your data center has grown over the years, stress not, SAN vendors have created software management tools to manage your heterogeneous environment with ease. But, better than multiple vendor management capability, all of your SAN environments can be centrally managed from this single interface. This capability provides efficient and centralized storage management.
10. Disaster Recovery
The cost of a SAN is high. As you can see, there's no entry for SAN being a particularly frugal technology in this list. However, in the case of disaster recovery, a SAN can and does earn back its high price by providing a speedy recovery when the clock is ticking. A SAN is a reliable and fast data recovery solution. Server systems might go offline, but the SAN remains available.
Choosing SAN, NAS, or DAS
But newer developments are changing the picture, pushing NAS up the performance scale and SANs down the cost curve, in some ways blurring the performance line between these two technologies. The arrival of iSCSI SANs is driving down the cost of SANs. The iSCSI protocol is a serial implementation of SCSI that aligns with IP packets. While operating at slower speeds and offering lower throughput than Fibre Channel, iSCSI uses standard networking gear, can operate over long distance for remote backup, and is easy for network administrators to understand and manage. However, because of its better performance, Fibre Channel is still the preferred technology for most data center applications.
This becomes clearer by contrasting SANs with another networked storage technology: NAS Network Attached Storage. While both NAS and SAN provide remote access to storage devices via a network, the similarity ends there. In technical terms, the primary distinction between the technologies is that NAS operates at a file level while SAN operates at a block level.
You have to dig somehow more into this topic.
Here are a few advantages of SAN:
Scalability
SAN has many advantages over DAS in your data center. Here are 10 reasons to consider making the leap from local storage to a SAN.
If you know, or have heard, one thing about a SAN, it's scalable. What does scalable mean? SAN scalability means that you don't have the limit of a handful of disks that you can attach to a system. SANs can grow to hundreds of disks in size, whereas your server has a physical limit of about a dozen.
2. Performance
SAN performance isn't affected by Ethernet traffic or local disk throughput bottlenecks. Data transmitted to and from a SAN is on its own private network partitioned off from user traffic, backup traffic and other SAN traffic.
3. Data Isolation
There's no chance of your data being copied or stolen by anyone sharing the same SAN with you. Not even the SAN admins can see your data. When correctly configured, SAN data is zoned. These zones protect your data from everyone else's on the same SAN. An example of SAN zone separation is how UNIX servers can connect to a SAN and Windows servers connect to the same SAN, but the data that each group of servers accesses is different. In effect, Windows systems can't "see" UNIX data and vice versa.
4. Uptime
There's nothing quite like a SAN to assure 100-percent storage availability. SAN systems require no reboots to add new disks, to replace disks or to configure RAID groups. The ability to stream data between SANs for data backup and recovery also increases performance by bypassing server systems completely.
5. Workload Isolation
Zoning also separates your workloads from one another on a SAN. Not only is your data protected by zoning, but it also provides a barrier against other non-related workloads from affecting your application's performance. Sharing a SAN isn't a performance problem for applications when zones are in place.
Long Distance Connectivity
SANs have the advantage over all other storage connectivity for distance at 10km (about 6 miles). Not that you'll necessarily use that distance capability, but it's there if you need it. Having the advantage of distance allows you to consolidate your storage into an isolated location dedicated to storage and separate from the systems it serves.
7. Increased Utilization
Rather than hundreds or thousands of partially utilized local disks wasting power and generating heat in your data center, you could have dozens of SAN disks have no wasted space on them. How so? Thin provisioning on the storage side (i.e., on the SAN) uses space more effectively than local storage does. As a system requires more storage, the SAN allocates it dynamically. Yes, this means that physical systems can enjoy thin provisioning just like your virtual ones do.
8. Bootable
Despite the benefit of more fully utilized disks, as highlighted in advantage No. 7, you do not need to use local disks for the server operating system. It's possible to run diskless physical servers and boot directly to the SAN for your operating system, swap space (pagefile), and all applications. That's right, just like virtual machines.
9. Centralized Management
If you have SAN arrays from several different vendors because your data center has grown over the years, stress not, SAN vendors have created software management tools to manage your heterogeneous environment with ease. But, better than multiple vendor management capability, all of your SAN environments can be centrally managed from this single interface. This capability provides efficient and centralized storage management.
10. Disaster Recovery
The cost of a SAN is high. As you can see, there's no entry for SAN being a particularly frugal technology in this list. However, in the case of disaster recovery, a SAN can and does earn back its high price by providing a speedy recovery when the clock is ticking. A SAN is a reliable and fast data recovery solution. Server systems might go offline, but the SAN remains available.
Choosing SAN, NAS, or DAS
But newer developments are changing the picture, pushing NAS up the performance scale and SANs down the cost curve, in some ways blurring the performance line between these two technologies. The arrival of iSCSI SANs is driving down the cost of SANs. The iSCSI protocol is a serial implementation of SCSI that aligns with IP packets. While operating at slower speeds and offering lower throughput than Fibre Channel, iSCSI uses standard networking gear, can operate over long distance for remote backup, and is easy for network administrators to understand and manage. However, because of its better performance, Fibre Channel is still the preferred technology for most data center applications.
This becomes clearer by contrasting SANs with another networked storage technology: NAS Network Attached Storage. While both NAS and SAN provide remote access to storage devices via a network, the similarity ends there. In technical terms, the primary distinction between the technologies is that NAS operates at a file level while SAN operates at a block level.
You have to dig somehow more into this topic.
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