[OpenIndiana-discuss] [zfs] zfs + iscsi = poor sequential reding performance

[Сисадмин]

 Hi everyone,

to make the long story short - i 've spent 6 weeks trting really hard, read tons of doc pages on the internet (get lots of knowledge to be honest)

so i can get very good results , however unfortunetely i cant get from iscsi+zfs good results about sequential reading.

the cominents

server with esxi:

proliant 180 G6,  RAM 64GB

NIC =   BCM95719A (4 ports)

esxi 5.5 u2


server directly (without switches) connects to server with zfs

zfs server:

proliant 180 G6, RAM 82GB

LSI 9207 HBA 

NIC =   BCM95719A (4 ports)

*  OpenIndiana Hipster 2016.04 Text Install USB (32/64-bit x86), 731M
sha256
i use round robin in esxi.
the number of iops to switch to another port nic = 1 iops.



my zfs pool is about 

6 x hdd seagate ST2000DM002   ( stripe of 3 mirrors)
zil  = 120 GB kingston

zvol volblocksize = 4k

ashift=12 for seagates
ashift=13 for kingston


primary cache=metadata
secondary cache = metadata

so i don't use arc for testing purposes i want to get good results without arc, later i will add it to the pool

i installl windows server 2012  +  iometer

testing pattern =  sequential read bs=512k  number of queues=5-8


I expect to get 250-270 MB\s (at least 150 MB\s for christ sake) about sequential reading, however i get just only 60 MB\s

I want to underline that i get very good results in seqeutnial writing

seq write 512k(iometer align=4k) , 8 threds ,tghroughput =226МБ\с lat=17.7 also i get good result about randon reading  rran read 4k(, 8 threads, iops= 614 lat= 13.0 


so the system kind of work. it's just about sequenatial reading problem.


i'm puzzled and fristrated, i want use zfs on iscsi but can't ,  i have to switch to iscsi + esxt3 .

What can you suggest ? is anyone struggle with bad reading ?

i ' ve searched a lot about it on the internet. - i can't find the pattern.

Sincerely yours
Alex K.