3 ms·
While block devices can go away, the notion of a file will probably continue to remain. We run clusters of ephemeral linux hosts, and while we use disk, we als
by itchyouch 12y ago
While block devices can go away, the notion of a file will probably continue to remain.
We run clusters of ephemeral linux hosts, and while we use disk, we also have plenty of hosts that run diskless. The disk mount point just becomes a tmpfs mount and the required minimal installation is made on a tmpfs partition which amounts to a trivial amount for hosting busybox and some conf files in /etc. Linux does appear to understand that tmpfs backed filestores are already in memory and do not need to synchronize pages and flush out dirty pages. That whole caching/memory layer for this fake block device is just not used at all.
- IgorPartola 12y agoThat's right, we already have a filesystem backed by RAM: tmpfs. Except now it's no longer so tmp. I suppose then yes we don't have to do much in the way of emulating block devices: just run tmpfs or it's later revisions and know that everything is permanent. In that case, this is not much of a leap for the current OS's to support it, which is great. I wonder if this means that theoretically mmap() can become a one liner now.
- bkeroack 12y agoWhy bother? I see two possibilities: - Two separate address spaces, one volatile (RAM) and one persistent (SSD). "Writing" to persistent storage is as simple as "mov [src],[dst]". - One global address space, with a page attribute of "volatile" (true/false). Writing is just as simple as above. At that point the OS and userspace are free to create whatever abstractions are necessary on top. They don't necessarily need to be filesystems or files per se.