[RC5] Result storage

Jeff Lawson bovine at distributed.net
Tue Jan 22 14:09:28 EST 2013


For RC5-72, the keymaster divides the entire keyspace into 4096 "keyspaces"
that each represent 2^28 "blocks" (each  block is 2^32 keys).  There are
basically three states that the keymaster can have for a keyspace:
unavailable, available, current.

For current keyspaces, this means we must track which blocks we have
distributed and which ones have been completed, which means 64MB of disk
space each (only 2 bits per block).  Generally we only have 5-10 current
keyspaces at any time.

For available keyspaces, we can accept results for them but we won't
attempt to distribute any more work from these keyspaces, because we've
already made one distribution pass.  These keyspaces each take only 32MB of
disk space (1 bit per block).  At this moment there are about 115 keyspaces
in this state.  For all 4096 keyspaces in this state, the keymaster will
need 128GB of diskspace.

For unavailable, no storage space is consumed and this represents any
keyspace that we have not worked on yet.

We also record log files of all activity completed, which is the bulk of
the disk usage.  For RC5-72, that currently grows at about 25MB compressed
per day.  We are currently operating on a 50GB partition on a server that
we have been running on continuously as the keymaster for almost 12 years,
though we are hoping to migrate to a newer machine with a couple of new 1TB
drives in the next few weeks.  The newer machine should greatly reduce the
amount of data shuffling that we must do operationally.


Jeff


On Sat, Jan 19, 2013 at 2:39 AM, Jarod McClintock
<myself at jlmcclintock.com>wrote:

> Out of complete interest I was wondering how all of the completed keys are
> stored. How big is the storage capacity, are the returned results smaller
> than the work units are when you sent out and how much does the result
> storage amount grow by each day or shrink depending on what way you look at
> it?
>
> Have a nice weekend
>
> Cheers
> Jarod
>
>
>
>
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