On 16/02/16 17:10, Mark Kirkwood wrote:
On 15/02/16 23:29, Kota TSUYUZAKI wrote:
Hello Mark,
AFAIK, a few reasons for that we still are in working progress for
erasure code + geo replication.
and expect to survive a region outage...
With that I mind I did some experiments (Liberty swift) and it looks
to me like if you have:
- num_data_frags < num_nodes in (smallest) region
and:
- num_parity_frags = num_data_frags
then having a region fail does not result in service outage.
Good point but note that the PyECLib v1.0.7 (pinned to Kilo/Liberty
stable) still have a problem which cannot decode the original data
when all feed fragments are parity frags[1]. (i.e. if set
num_parity_frags = num_data frags and then, num_parity_frags comes
into proxy for GET request, it will fail at the decoding) The problem
was already resolved in the PyECLib/liberasurecode at master
branch and current swift master has the PyECLib>=1.0.7 dependencies so
if you thought to use the newest Swift, it might be not
a matter.
Ah right, in my testing I always took down my "1st" region...which will
have had data fragments therein. For interest I'll try to provoke a
situation where I have all parity ones to assemble (and see what happens).
So tried this out - still works fine. Checking version of pyeclib I see
Ubuntu 15.10 is giving me:
- Swift 2.5.0
- pyeclib 1.0.8
Hmmm - Canonical deliberately upping the version of pyeclib (shock)?
Interesting...anyway explains why I cannot get it to fail. However, all
your other points are noted, and again thanks!
Regards
Mark
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