[Bugs] [Bug 1559084] [EC] Read performance of EC volume exported over gNFS is significantly lower than write performance

[bugzilla at redhat.com]

https://bugzilla.redhat.com/show_bug.cgi?id=1559084

nchilaka <nchilaka at redhat.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ON_QA                       |VERIFIED



--- Comment #8 from nchilaka <nchilaka at redhat.com> ---
onqa validation on 3.12.2-11
as P0 cases(that is cases developed for testing the bug) are passing moving to
verified

##### TEST PLAN ###########
due to changing read-policy to gfid-hash, the read perf has improved
(below is for a 10mb file)


tc#1-->PASS (P0)
md5sum took below time for congruent files(they are copies of each other)

[root at dhcp35-72 dd]# time md5sum file.3  --------->with now default gfid-hash
based
e84853d61440dada29a64406f17de488  file.3

real    0m7.080s
user    0m0.195s
sys    0m0.080s
[root at dhcp35-72 dd]# time md5sum file.4  ---->with round-robin
e84853d61440dada29a64406f17de488  file.4

real    0m43.652s
user    0m0.207s
sys    0m0.297s


tc#2:PASS (P0)
check for the default of read-policy, it must be gfid-hash

tc#3:PASS  (P1)
try setting read-policy to different values, must allow either of round-robin
or gfid-hash

[root at dhcp35-9 glusterfs]# gluster v get general all|grep gfid
cluster.randomize-hash-range-by-gfid    off                                     
storage.build-pgfid                     off                                     
storage.gfid2path                       on                                      
storage.gfid2path-separator             :                                       
disperse.read-policy                    gfid-hash                               
[root at dhcp35-9 glusterfs]# gluster v gset general disperse.read-policy
unrecognized word: gset (position 1)
[root at dhcp35-9 glusterfs]# gluster v gset general disperse.read-policy add
unrecognized word: gset (position 1)
[root at dhcp35-9 glusterfs]# gluster v set general disperse.read-policy add
volume set: failed: option read-policy add: 'add' is not valid (possible
options are round-robin, gfid-hash.)



tc#4: ->PASS (P1) however raised an RFE BZ#1583662 - RFE: load-balance reads
even when the read-policy is set to gfid-hash when multiple clients read same
file
read same file from multiple clients, should not impact, both clients from read
from same set of bricks


tc#5-->PASS (P2)
softlink to a file and read it?
no problem, as it still reads from source file 

tc#6->PASS (P0)
have a file being read and when one of the hashed bricks goes down, no EIO must
be seen, as the non-hashed brick must start to serve data
Test above even by disabling nfs client cache(passed)
checked even with 2 bricks down

tc#7->Pass but can be improved (P2)
Once the hashed brick comesup check if the hashed brick starts to serve the
data
Result->yes, for this reason, i raised a bz#1583643 - avoid switching back to
the gfid-hashed brick once it is online(up) and instead continue reads from
non-hashed brick 

[root at dhcp35-126 dispersevol1]# dd if=big-dd//10mb of=/dev/null bs=1024
count=10000000
10000000+0 records in
10000000+0 records out
10240000000 bytes (10 GB) copied, 570.747 s, 17.9 MB/s


tc#8:->PASS (P2)
if brick which is not hashed is brought down should not impact the read

tc#9:
raised bz#1583643 - avoid switching back to the gfid-hashed brick once it is
online(up) and instead continue reads from non-hashed brick

Also raised below BZ
1583667 - nfs logs flooded with "Connection refused); disconnecting socket"
even after the brick is up due to stale sockets

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