Hello,

We're using nginx-1.2.8 to serve large static files for video
streaming. However all nginx worker_processes are in "D" state and HDD I/O
utilization is 99%.

[root@DNTX010 ~]# ps aux |grep nginx
root 3046 0.0 0.0 20272 688 ? Ss 20:39 0:00 nginx:
master process nginx
nginx 3047 3.2 0.9 94480 74808 ? D 20:39 0:03 nginx:
worker process
nginx 3048 1.4 0.3 52104 31388 ? D 20:39 0:01 nginx:
worker process
nginx 3049 0.2 0.1 33156 12156 ? S 20:39 0:00 nginx:
worker process
nginx 3050 0.1 0.1 29968 8844 ? D 20:39 0:00 nginx:
worker process
nginx 3051 0.2 0.1 30332 10076 ? D 20:39 0:00 nginx:
worker process
nginx 3052 2.7 0.8 91788 69504 ? D 20:39 0:02 nginx:
worker process
nginx 3053 0.3 0.0 25632 5384 ? D 20:39 0:00 nginx:
worker process
nginx 3054 0.2 0.1 36032 15852 ? D 20:39 0:00 nginx:
worker process
nginx 3055 0.4 0.2 37592 17396 ? D 20:39 0:00 nginx:
worker process
nginx 3056 0.2 0.1 32580 11028 ? S 20:39 0:00 nginx:
worker process
nginx 3057 0.3 0.2 39288 19116 ? D 20:39 0:00 nginx:
worker process
nginx 3058 0.3 0.2 41764 19744 ? D 20:39 0:00 nginx:
worker process
nginx 3059 0.3 0.1 31124 10480 ? D 20:39 0:00 nginx:
worker process
nginx 3060 1.0 0.3 52736 31776 ? D 20:39 0:01 nginx:
worker process
nginx 3061 1.1 0.3 51920 29956 ? D 20:39 0:01 nginx:
worker process
nginx 3062 1.6 0.4 58808 35548 ? D 20:39 0:01 nginx:
worker process


[root@DNTX010 ~]# iostat -x -d 3
Linux 2.6.32-358.6.2.el6.x86_64 (DNTX010.local) 07/16/2013
_x86_64_ (8 CPU)

Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz
avgqu-sz await svctm %util
sda 30.28 177.37 260.32 2.96 38169.26 1442.70
150.46 2.29 8.70 3.52 92.78

Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz
avgqu-sz await svctm %util
sda 4.33 0.00 544.00 0.00 34376.00 0.00
63.19 43.83 75.25 1.84 100.00

Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz
avgqu-sz await svctm %util
sda 9.00 6.33 547.67 0.67 34637.33 56.00
63.27 48.01 86.20 1.82 100.00

Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz
avgqu-sz await svctm %util
sda 0.00 0.67 568.00 2.33 36024.00 29.33
63.21 54.98 101.10 1.75 100.00

Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz
avgqu-sz await svctm %util
sda 0.00 4.33 560.33 1.33 35712.00 45.33
63.66 37.20 65.06 1.78 100.00


Nginx.conf :

http {
include mime.types;
default_type application/octet-stream;
client_body_buffer_size 128K;
sendfile_max_chunk 128k;
client_max_body_size 800m;
client_header_buffer_size 256k;
large_client_header_buffers 4 256k;
output_buffers 1 512k;
server_tokens off; #Conceals nginx version
#access_log logs/access.log main;
access_log off;
error_log warn;
sendfile on;
# aio on;
# directio 512k;
ignore_invalid_headers on;
client_header_timeout 3m;
client_body_timeout 3m;
send_timeout 3m;
keepalive_timeout 0;
reset_timedout_connection on;
}

We've also tried enabling aio directive but nothing changed. Help will be
highly appreciated.

Thanks
Shahzaib
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