从远程网络内存映射文件或设备块读取是否比从本地 7200rpm HDD 读取更快？
或者更确切地说，远程 RAM 与本地磁盘访问相比如何？ 如果答案是“视情况而定”，那么条件是什么？ 数据访问模式、读写比率、距离等。
最后，如果本地磁盘是 NetApp 文件管理器怎么办？
谢谢。
Or rather how does remote RAM compare against local Disk access?
If the answer is "it depends", what are the conditions?
Data access patterns, ratio of read-to-writes, distance etc.
Finally, what if the local disks are NetApp filers?
Thanks.
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这始终是延迟与带宽的问题。与本地磁盘的毫秒相比，远程内存的访问时间对于千兆位网络而言约为微秒，对于 InfiniBand 和 10 GigE 而言约为 100 纳秒（例如 希捷 ST3250318AS - 4.1ms)。一旦磁盘到达连续的块，它的传输速率将超过千兆位网络，这就是为什么本地磁盘主要被认为更快。
It is as always a question of latency versus bandwidth. The access time to remote memory will be on the order of microseconds for gigabit networking, 100s of nanoseconds for InfiniBand and 10 GigE compared with milliseconds for local disks (example Seagate ST3250318AS - 4.1ms). As soon as the disk has hit a contiguous block it's transfer rate will exceed gigabit networking which is why local disk is predominantly considered faster.
一般来说，本地硬盘会更快，因为远程连接将受到网络带宽+协议开销的限制。
如果“本地”（如果它们位于远程 netapp 上，则它们不是真正的本地）是 netapp，则它们通常会比远程 RAM 慢。由于 netapps 很可能具有相同的网络瓶颈 + 协议开销，加上文件系统开销 (nfs/smb)，并且很可能存在某种 RAID 开销。
In general the local HDD will be faster, as the remote connection will be limited by the network bandwidth + protocol overhead.
If "local" (they're not really local if they're on a remote netapp) are netapps, they will be generally slower than remote RAM. Since netapps will most likely have the same network bottleneck + protocol overhead, plus file system overhead (nfs/smb), and most likely some sort of RAID overhead.