Redhat Enterprise Advanced Server 3.0性能问题

luomingxue

speed of Journaling File System ext3
You can set Journaling mode data=ordered(default)/writeback/journal/

I can do it use mount/umount

But I couldn't figure out how to do it in fstab.
in fstab
/dev/md2                /boot                   ext3    -o data=writeback        1 2

showed error in this entry when bootup.  
Anybody can help how to add mount options in fstab?
What the correct syntas?

speed of Journaling File System ext3 from redhat
http://www.redhat.com/support/wpapers/redhat/ext3/index.html#speed

luomingxue

i'll test system under different kernels.
Someone said
2.4.22-1.2115.nptlsmp from fedora solved his I/O probs.
I ued 2.4.22-1.2174 does not work.

run the following program
./test_write aaa 20 200

and do
/sbin/hdparm -Tt /dev/md2
while the program is running

from
http://www.redhat.com/archives/taroon-list/2003-December/msg00174.html
test_write.c
#include <stdio.h>;
#include <unistd.h>;
#include <errno.h>;
#include <stdlib.h>;
#include <string.h>;
#include <sys/types.h>;
#include <sys/stat.h>;
#include <fcntl.h>;
#include <sys/time.h>;


#define LOG_FILENAME "/tmp/error.log"
#define MAX_FILE_NAME        32
#define MILLISEC_DIFF(new, old, diff)   {                               \
        (diff) = (((new).tv_sec  - (old).tv_sec)  * 1000L ) +           \
                 (((new).tv_usec - (old).tv_usec) / 1000L );            \
}

int main(int argc, char* argv[]) {

        char* data, log_str[1024], filename[MAX_FILE_NAME];
        int frequency, chunk_len, flags, elapsed, interval, sleep_time,
                fd = -1, fd2 = -1;
        struct timeval t1, t2;
        mode_t          mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH;
       

        if(argc != 4) {
                printf("usage: test_writes filename frequency(eg. 20 for 50 ms) write_size(Bytes)\n";
                _exit(1);
        }
       
        bzero(filename, MAX_FILE_NAME);
        strncpy(filename, argv[1], MAX_FILE_NAME -1);
        frequency = atoi(argv[2]);
        chunk_len = atoi(argv[3]);

        printf("filename <%s>; frequency <%d>; chunk_len <%d>;\n", filename, frequency, chunk_len);

        flags = O_CREAT | O_WRONLY | O_TRUNC;
        fd2 = open(LOG_FILENAME, O_WRONLY | O_CREAT | O_APPEND, mode);
        fd = open(filename, flags);

        if(fd < 0) {
                perror("Unable to open the input file";
                _exit(2);
        }
       
        if(fd2 < 0) {
                perror("Unable to open the log file";
                _exit(2);
        }

        data = (char*) malloc(sizeof(char)*chunk_len);
        if(data == NULL) {
                perror("Unable to allocate the input buffer";
                _exit(3);
        }

        interval = (int)(((double)1000/frequency));
        while(1) {
                gettimeofday(&t1, NULL);
                write(fd, data, chunk_len);
                gettimeofday(&t2, NULL);
                MILLISEC_DIFF(t2, t1, elapsed);
                if(elapsed >;= interval)  {
                        sprintf(log_str,"<%ld>;<%ld>; write to file <%s>;<%d>;\n", t1.tv_sec, t1.tv_usec/1000L, filename, elapsed);
                        write(fd2, log_str, strlen(log_str));
                }
                sleep_time = (interval - elapsed)*1000;
                if(sleep_time >; 0)        
                        usleep(sleep_time);
        }
}

luomingxue

Final update:

Added 1G memory module,total memory 768M to 1.5G,
Change kernel to
2.4.22-1.2115

No change to kjournald.

No high iowait time anymore!
mission accomplished!

open question:
1. how to write -o data=writeback in fstab, anybody can give me an example?
2. how to check which process is using cpu, memory?
3. MYsql performance may need to be tuned, any tips?