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= Parallel File Systems: File Systems for HPC Clusters =
== 1. 重點 ==
=== 1.1 作者將 Cluster FS 分為兩類： ===
   * DFS (Distributed File Systems)
     * ”parallel” as they utilize '''''multiple data servers'''''
   * PFS (Parallel File Systems)
     * use a '''''single server''''', are not necessarily parallel, they can give the user '''''”parallel access”''''' to a file system.

=== 2.2 DFS === 
 * '''2.2.1''' DFS are network based(i.e. the actual storage hardware is not necessarily on the nodes) but it not necessarily parallel (i.e.there may not be multiple servers that are delivering the file system).
 * [wiki:rock/paper/PFS_HPC/NFS '''2.2.2''' 作者先舉 NFS 來介紹：]
 * '''2.2.3''' 作者第二個舉的是 '''Clustered NAS：'''
   * Clustered NAS systems were developed to make NAS systems more scalable and to give them more performance
   * Uses several filer heads instead of a single one. The filer heads are then connected to storage.
   * __'''Two Arch：'''__
     1. several file heads each have some storage assigned to them.
        * First approach is used by !NetApp (!NetApp-GX)
     2. the filer heads are really gateways from the clients to a parallel file system.             
        * filer heads communicate with the client using NFS over the client network but access the parallel file system on a private storage network.
        * allows the ClusterNAS to be scaled quite large because you can just add more gateways– which also increases aggregate performance because there are more NFS gateways.
        * Used by Isilon. And Panasas, IBM’s GPFS, and other parallel file systems when they are running in a NFS mode.
   * The problem is that you have limited performance to the client because you are using NFS as the communication protocol. Most of the Cluster NAS solutions use a single GigE connection so you are limited to about 90-100 MB/s at most to each client.

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=== 2.3 PFS === 
 * Provide lots of I/O for clusters
 * provide a centralized file system for clusters
   * Centralized file systems can ease a '''''management burden''''' & '''''improve the scalability''''' of cluster storage
 * PFS are distinguished from DFS because the clients contact multiple storage devices instead of a single device or a gateway
 * 作者將 PFS 分為兩類：
   1. [wiki:rock/paper/PFS_HPC/PFS-type1 First Type] First group uses more '''''traditional methods''''' such as file locking as part of the file system (block based, or even file based, schemes)
   2. [wiki:rock/paper/PFS_HPC/PFS-type2 Second type: Object based file systems]

 

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== 想法 ==
 * 此篇論點屬 survey 性質，可用於撰寫 DFS Paper 的文獻探討 [http://en.wikipedia.org/wiki/List_of_file_systems#Distributed_file_systems DFS from wiki]