hi,
i'm quite new to riak and only know it from the docs available online.
to be honest, i did not search for a key/value store, but for a reliable
(HA) distributed, replicated filesystem that allows dynamic growth.
all these filesystems i've dealt with are either immature, abandoned, or
are limited in features like dynamic scaling, snapshotting or fail in
out-of-diskspace scenarios (as they don't give you high availability and
data protection at the same time).
somehow i stumbled upon this project and liked its features, despite not
being a filesystem at all. i can live with its flat structure if it'll
bring me all the other features i need.
so i'm now at the point that after reading the online docs without any
hands-on experience leaves some questions unanswered.
since i'm used to storing all data in a filesystem, our application's
storage interface would need a complete rewrite to interface with riak
and provide the same services as before. therefore i'd like to ask you
to share your knowledge and experience.
1) are snapshots provided?
i guess they aren't, but i'm more interested weather i can use the
vectorclocks for that.
i only need one snapshot and live data to provide an consistent old
view of the data for our staging instance.
2) how does riak deal with different storage capacities of the different
nodes? is it a problem, if some nodes provide less space than others? is
data distributed uniformly accross all nodes or is its capacity taken
into account?
3) we've got quite huge files for a database to store. is that a
problem? what storage backend do you propose?
currently we see the following distribution, but i expect more in
the range from 512MB to 4GB to come in future:
< 1KB: 64053
1KB - 1MB: 873795
1MB - 2MB: 4776
2MB - 4MB: 3131
4MB - 8MB: 3136
8MB - 16MB: 2842
16MB - 32MB: 3136
32MB - 64MB: 4032
64MB - 128MB: 3118
128MB - 256MB: 3361
256MB - 512MB: 3221
512MB - 1GB: 1423
1GB - 2GB: 75
4) is range access possible to read parts of a file^W value or do i need
to stream the whole file through? this would not perform well on guge
values.
5) to reduce the impact of a disk failure on the storage backend and i'd
like each disk of a server to be assigned to its own riak-node. i guess
healing the failed node ofter replacement is faster than raid recovery
and less data is at risk.
is it possible to reflect the hardware hierarchy in some way to
influence the place for replicas? CephFS offers this to make sure
replicas are hold on different hardware or even in different locations.
e.g. a STORAGE is in a SERVER, which is in a RACK, which is in a
DATACENTER. replicas of a file in a STORAGE should never be placed
inside the same SERVER, (or RACK, or DATACENTER).
6) what happens, if less that R or W nodes report data? does it mean not
found or not available? even if the data is on an currently offline node.
7) can he client applications connect to some random node?
should it simply retry the next one in the list upon failure?
8) is the data reported back on read is compared/verifies with all
replicas to ensure consistency or just its metadata (if R>1)
9) is data integrity in storage backend is secured through checksums?
these are the questions puzzling me at the moment.
if you know some filesystem that matches my featurelist, please don't
hesitate to answer them off-topic ;-)
cheers
pille
_______________________________________________
riak-users mailing list
riak-users@lists.basho.com
http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com
