[tahoe-dev] Using multiple disks on a node

Avi Freedman freedman at freedman.net
Sun Apr 21 21:33:02 UTC 2013


Hi, had a question and a comment.

Was looking at the FAQ and saw Q8 re using more than one storage directory.
For now 4 boxes each with 16 x 1.5t disks.
Later this week, 9 boxes each with 45 x 1.5t disks and 8 physical cores (16 
w/ hyperthreading).

It discusses symlinks then running LVM to glorp disks together into one
usable mount point, which could be a slight perf hit if blocks get
spread across disks.  But the bigger issue would be recovery if an underlying
disk dies with LVM.  Unless you use RAID which could really limit max 
throughput.

So the suggestion is linking to mhdfs:

http://romanrm.ru/en/mhddfs

Which is a union filesystem that can unify underlying target mount points and
present a single view.  Stock, it fills a target then goes on to the next, then
the next, etc.

Some patches to implement hashing across the underlying targets is here:

http://readnews.com/mhddfs-diff.txt

Will get it resubmitted.

The question is...

Are there any available examples of configs for running multiple server 
processes?  Maybe I missed them int the docs, sorry if so.  

Thanks,

Avi




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