[IT新应用]存储入门-文件级存储及块级别存储的选择

http://www.techrepublic.com/blog/the-enterprise-cloud/block-level-storage-vs-file-level-storage-a-comparison/

这一篇文章里面提到了文件级存储和块级别存储的主要差别。以下英文为原文，汉语翻译为本人翻译。如有需要引用，请发邮件联系或留言。

In its most basic form, think of block level storage as a hard drive in a server except the hard drive happens to be installed in a remote chassis and is accessible using Fibre Channel or iSCSI.

块级别存储的基本形式，你可以把他理解为服务器里面的一个硬盘，但是这块硬盘刚好装在了远处的机柜，通过FC或者iSCSI访问。

From a use case standpoint, there are a lot of applications that make use of this block-level shared storage, including:

• Databases. This is especially true when you want to cluster databases, since clustered databases need shared storage.
• Exchange. Although Microsoft has made massive improvements to Exchange, the company still does not support file level or network-based (as in, CIFS or NFS) storage. Only block level storage is supported.
• VMware. Although VMware can use file level storage via Network File System (NFS), it's very common to deploy VMware servers that use shared VMFS volumes on block level storage.
• Server boot. With the right kind of storage device, servers can be configured to boot from block level storage.

从用户使用角度出发，很多应用都需要使用块级别的共享存储。包括如下这些场景：

• 数据库，特别是你需要做数据库集群，因为集群需要共享存储。
• Exchange服务器，虽然微软在exchange方面已经做出了巨大的改进，但是该软件仍然不支持文件级或者基于网络协议（如CIFS、NFS）的存储。
• VMWAre, 虽然VMware可以通过NFS协议来使用文件级存储，但是更通常的做法是使用块级别存储上的共享VMFS卷来部署VMware 服务器。
• 服务器启动。使用了正确的存储设备，服务器可以从块级别存储上直接启动。

If you're looking for storage that screams — that is, if you need high levels of storage performance — be very careful with the file level option. In most cases, if you need high levels of performance, you should look at the block level options. Block level devices are generally configurable for capacity and performance. Although file-level devices do have a performance component, capacity is usually the bigger consideration.

File level use cases are generally:

• Mass file storage. When your users simply need a place to store files, file-level devices can make a lot of sense.
• VMware (think NFS). VMware hosts can connect to storage presented via NFS in addition to using block level storage.

如果你正在寻找高性能的存储，你要特别留意文件级别这个选项是否适合。在很多场景，如果你需要高性能的存储，你应该选择块级别的存储。

块级别的存储通常可以根据容量及性能来进行配置。虽然文件级存储也有性能组件，但是容量通常是更大的考虑因素。

文件级使用场景通常包括：

• 大量文件存储。当你的用户仅仅需要一个地方存储文件，文件级存储是一个好的选择。
• VMFS（当使用NFS时），除了使用块级别存储，VMware主机还可以通过NFS协议连接文件级存储。