Роман, Дмитрий, спасибо за рекомендации.
Падение воркеров nginx'а не было замечено. При рестарте nginx воркеры недолго находятся в состоянии "shutting down". Тут все хорошо.
Сейчас кеш был значительно уменьшен и включен дебаг.
Проблема пока не проявляется, но вижу подозрительные вещи в дебаг логе:
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire: #1 1 29fddad7
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire: #0 1 21c1cd6e
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire: #1 1 29fddad7
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire: #0 1 304bc486
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire: #1 1 29fddad7
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire: #0 1 5468f149
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire: #1 1 29fddad7
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire: #0 1 0614276a
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire: #1 1 29fddad7
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire: #0 1 47d72b84
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire: #1 1 29fddad7
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire: #0 1 6ded07ab
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire: #1 1 29fddad7
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire: #0 1 7c700af9
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire: #1 1 29fddad7
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire: #0 1 2f6fc358
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire: #1 1 29fddad7
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire: #0 1 1b1dda91
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire: #1 1 29fddad7
2015/04/28 13:40:38 [debug] 22500#0: http file cache forced expire: #0 1 1c3dda56
(Обратите внимание на 29fddad7)
Хотя в файловой системе его не нахожу:
# ls -all /opt/nginx-cache-images1/29/fd/
total 156
drwx------ 2 www-data www-data 12288 Apr 28 13:47 .
drwx------ 258 www-data www-data 4096 Apr 17 11:04 ..
-rw------- 1 www-data www-data 11120 Apr 26 22:08 187415d376209c37038d3e536a4cfd29
-rw------- 1 www-data www-data 6653 Apr 28 13:41 1e43883d6ddcfb56e9ea84f4e2dffd29
-rw------- 1 www-data www-data 23033 Apr 28 13:41 5bdba55383559ec9f50fe6eec83cfd29
-rw------- 1 www-data www-data 13527 Apr 28 13:45 7983c75832ea3f0458e4315b83dcfd29
-rw------- 1 www-data www-data 11731 Apr 28 13:47 85e329c59da26ddac0e5844adc23fd29
-rw------- 1 www-data www-data 17182 Apr 28 13:44 90d0b75025acf141f8fd5f0bc431fd29
-rw------- 1 www-data www-data 17620 Apr 28 13:45 a1498de45e99ca3538f59da22f9cfd29
-rw------- 1 www-data www-data 4805 Apr 28 13:43 d33a7459a80456c5dc2aa4f56a84fd29
-rw------- 1 www-data www-data 17668 Apr 28 13:47 d7deedc7100d675b024eaebb99c6fd29
Открытых файлов в этой директории на данный момент тоже нет.
