Messages in this thread | | | Date | Tue, 19 May 2015 11:33:54 -0400 | Subject | Re: Userspace Block Device | From | Bill Speirs <> |
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On Tue, May 19, 2015 at 11:19 AM, One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> wrote: >> ... rack up a huge bill with Amazon or Google > > And you probably would because the block layer will see a lot of I/O > requests that you would really want to process locally, as well as stuff > caused by working at the block not file level (like readaheads). > > You also can't deal with coherency this way - eg sharing the virtual disk > between two systems because the file system code isn't expecting other > clients to modify the disk under it. > > Rather than nbd you could also look at drbd or some similar kind of > setup where you keep the entire filestore locally and write back changes > to the remote copy. As you can never share the filestore when mounted you > can cache it pretty aggressively.
What kinds of things could I process locally? I was thinking I could keep a bitmap of "sectors" that have never been written to, then just return zeroed-out sectors for those. What else I could do? Thoughts?
I'm not looking to share the filesystem, just never have to buy a bigger disk again and get pseudo-backup along with it (I realize things in my cache would be lost if my house burned to the ground).
drbd isn't really what I'm looking for, because I don't want to have to buy a disk that's large enough to fit everything. Just a small fast SSD (or RAM disk) to cache commonly used files, then spill-over to the cloud for everything else. In theory, I would have a /home that is "infinite", and fairly fast for things that are cached.
Thanks for the thoughts/points!
Bill-
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