Monday, January 14, 2008

DO NOT USE O_DIRECT with EXT3

O_DIRECT under high load causes these issues

This is a symptom

Losing some ticks... checking if CPU frequency changed.
warning: many lost ticks.
Your time source seems to be instable or some driver is hogging interrupts
rip __do_softirq+0x4d/0xd0
ttyS1: 1 input overrun(s)
ttyS1: 1 input overrun(s)
ttyS1: 1 input overrun(s)
ttyS1: 1 input overrun(s)
ttyS1: 1 input overrun(s)



BUT THE REAL PROBLEM is it Locks up the partition that the ibdata file is on.




Systems where the server locked up.

2.6.9-34.ELsmp #1 SMP Fri Feb 24 16:56:28 EST 2006 x86_64 x86_64 x86_64 GNU/Linux

total used free shared buffers cached
Mem: 16412760 16389976 22784 0 82440 686368
-/+ buffers/cache: 15621168 791592
Swap: 8393952 144 8393808


I had O_DIRECT running in production for over a month on some pretty loaded servers, but once I put it on some older servers, all hell broke loose.

Pretty Loaded is defined as

1000 qps mainly selects mixed with large ranges at a high concurrency of 30 threads.

CPU WIO is around 10-15% (acceptable thresholds)


If you insist on running O_DIRECT I recommend

1. Test O_DIRECT on ever OS version in your farm
2. Test O_DIRECT by producing so much load that it's unrealistic.

9 comments:

Stoner said...

Can you provide any details around this? What is a "pretty loaded server?" What is the hardware configuration? What kind of application workload was this database? Since we run a lot of MySQL databases (using InnoDB) on ext3 file systems, I'm concerned but without anything to go on, I can't take this very seriously.

Dathan said...

I am still tracking down why O_DIRECT does not work with EXT3 on my 2.6 RHEL version. All I have to go on is when I turned it off the partition never froze again.

BrianAker said...

IM me, it turns out you do have support.
-Brian

feedblog.org said...

We're using O_DIRECT on innodb for > 60 days now. No problems with locked partitions.

guillermofranco said...

I have the same load here (1000 qps) with ext3 and O_DIRECT (mysql 5.0.44sp1, ubuntu dapper server), no issues for more than 6 months. Looks like a platform-specific problem to me.

Dathan said...

Thank you for your input. We still have no clue as to why it's not working for us.

Maybe a conflict with MegaRaid?

Anonymous said...

I think it's pretty irresponsible to immediately assume ext3 was culpable in your issue. Did you remount with ext2 or xfs for example, repeat the situation that caused the crash, and NOT have it crash?

I'm trying to understand where ext3 fits into your hypothesis.

sexy said...

情趣用品,情趣用品,情趣用品,情趣用品,情趣用品,情趣用品,情趣用品,情趣用品,情趣,情趣,情趣,情趣,情趣,情趣,情趣,情趣,按摩棒,跳蛋,充氣娃娃,情境坊歡愉用品,情趣用品,情人節禮物,情惑用品性易購

免費A片,AV女優,美女視訊,情色交友,免費AV,色情網站,辣妹視訊,美女交友,色情影片,成人影片,成人網站,A片,H漫,18成人,成人圖片,成人漫畫,情色網,日本A片,免費A片下載,性愛

A片,色情,成人,做愛,情色文學,A片下載,色情遊戲,色情影片,色情聊天室,情色電影,免費視訊,免費視訊聊天,免費視訊聊天室,一葉情貼圖片區,情色,情色視訊,免費成人影片,視訊交友,視訊聊天,視訊聊天室,言情小說,愛情小說,AIO,AV片,A漫,av dvd,聊天室,自拍,情色論壇,視訊美女,AV成人網,色情A片,SEX

情趣用品,A片,免費A片,AV女優,美女視訊,情色交友,色情網站,免費AV,辣妹視訊,美女交友,色情影片,成人網站,H漫,18成人,成人圖片,成人漫畫,成人影片,情色網


情趣用品,A片,免費A片,日本A片,A片下載,線上A片,成人電影,嘟嘟成人網,成人,成人貼圖,成人交友,成人圖片,18成人,成人小說,成人圖片區,微風成人區,成人文章,成人影城,情色,情色貼圖,色情聊天室,情色視訊,情色文學,色情小說,情色小說,臺灣情色網,色情,情色電影,色情遊戲,嘟嘟情人色網,麗的色遊戲,情色論壇,色情網站,一葉情貼圖片區,做愛,性愛,美女視訊,辣妹視訊,視訊聊天室,視訊交友網,免費視訊聊天,美女交友,做愛影片

av,情趣用品,a片,成人電影,微風成人,嘟嘟成人網,成人,成人貼圖,成人交友,成人圖片,18成人,成人小說,成人圖片區,成人文章,成人影城,愛情公寓,情色,情色貼圖,色情聊天室,情色視訊,情色文學,色情小說,情色小說,色情,寄情築園小遊戲,情色電影,aio,av女優,AV,免費A片,日本a片,美女視訊,辣妹視訊,聊天室,美女交友,成人光碟

情趣用品.A片,情色,情色貼圖,色情聊天室,情色視訊,情色文學,色情小說,情色小說,色情,寄情築園小遊戲,情色電影,色情遊戲,色情網站,聊天室,ut聊天室,豆豆聊天室,美女視訊,辣妹視訊,視訊聊天室,視訊交友網,免費視訊聊天,免費A片,日本a片,a片下載,線上a片,av女優,av,成人電影,成人,成人貼圖,成人交友,成人圖片,18成人,成人小說,成人圖片區,成人文章,成人影城,成人網站,自拍,尋夢園聊天室

sex said...

徵信社
情趣用品
情趣用品
情趣用品
情趣
情趣


SM
充氣娃娃


SM
性感睡衣


免費視訊聊天室
aio交友愛情館
愛情公寓
情色貼圖
情色文學
情色小說
情色電影
情色論壇
成人論壇
辣妹視訊
視訊聊天室
情色視訊
免費視訊

免費視訊聊天
視訊交友網
視訊聊天室
視訊美女
視訊交友
ut聊天室
聊天室
豆豆聊天室
尋夢園聊天室
聊天室尋夢園
080聊天室
080苗栗人聊天室
女同志聊天室

上班族聊天室
小高聊天室






免費視訊聊天
免費視訊聊天室
免費視訊
ut聊天室
聊天室
豆豆聊天室 聊天室尋夢園
影音視訊聊天室


色情遊戲
寄情築園小遊戲
情人視訊網
辣妹視訊
情色交友

成人論壇
情色論壇
愛情公寓
情色
色情聊天室
色情小說
做愛
做愛影片
性愛


一葉情貼圖片區
情趣用品


辣妹視訊
美女視訊
視訊交友網
視訊聊天室
視訊交友
視訊美女