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  • What kind of process should I use to learn a big system?

    - by user394128
    I just joined a new company and started to study one of the their bigger system. For me to be productive, I need to understand the entire system without too much help. Other programers are really busy and dont' have time to hold my hands. I used to use brain map to draw a pictorial representation of the system. Any recommendations on what is the right appproach to dissect a big program? It is a .net prgoram by the way.

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  • Scanner Review: Fujitsu ScanSnap S1300

    The world of computer peripherals moves almost as fast as a busy business traveler. Fujitsu keeps up with both with its new portable scanner complete with automatic document feeder and business card import to Outlook.

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  • Scanner Review: Fujitsu ScanSnap S1300

    The world of computer peripherals moves almost as fast as a busy business traveler. Fujitsu keeps up with both with its new portable scanner complete with automatic document feeder and business card import to Outlook.

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  • Effective Website Search Engine Optimization - What Does That Mean?

    The Internet has become a very busy place. It's also become a sort of global marketplace where people all over the world come to buy and sell goods. Not much new to anyone in that statement, but it does beg the question, what's the best way for you to find customers both locally to Saskatoon and globally... and let them know you're online?

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  • Netbook Buying Guide

    The plethora of netbook choices may appear remarkably similar, yet the differences in hardware make all the difference for the busy professional. Here are some tips on selecting the best netbook for your needs.

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  • 10 Tips to Follow When Hiring Sub-Contractors For Website Work

    I had several mentors that I respect tell me that we needed to change up our website home page. So I hired a company to do that that I knew of, and respected. After 4 weeks, all I had was a PSD file (Adobe) and an apology that they could not do the job because they had gotten really busy and lost their primary webmaster.

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  • socket operation on nonsocket or bad file descriptor

    - by Magn3s1um
    I'm writing a pthread server which takes requests from clients and sends them back a bunch of .ppm files. Everything seems to go well, but sometimes when I have just 1 client connected, when trying to read from the file descriptor (for the file), it says Bad file Descriptor. This doesn't make sense, since my int fd isn't -1, and the file most certainly exists. Other times, I get this "Socket operation on nonsocket" error. This is weird because other times, it doesn't give me this error and everything works fine. When trying to connect multiple clients, for some reason, it will only send correctly to one, and then the other client gets the bad file descriptor or "nonsocket" error, even though both threads are processing the same messages and do the same routines. Anyone have an idea why? Here's the code that is giving me that error: while(mqueue.head != mqueue.tail && count < dis_m){ printf("Sending to client %s: %s\n", pointer->id, pointer->message); int fd; fd = open(pointer->message, O_RDONLY); char buf[58368]; int bytesRead; printf("This is fd %d\n", fd); bytesRead=read(fd,buf,58368); send(pointer->socket,buf,bytesRead,0); perror("Error:\n"); fflush(stdout); close(fd); mqueue.mcount--; mqueue.head = mqueue.head->next; free(pointer->message); free(pointer); pointer = mqueue.head; count++; } printf("Sending %s\n", pointer->message); int fd; fd = open(pointer->message, O_RDONLY); printf("This is fd %d\n", fd); printf("I am hhere2\n"); char buf[58368]; int bytesRead; bytesRead=read(fd,buf,58368); send(pointer->socket,buf,bytesRead,0); perror("Error:\n"); close(fd); mqueue.mcount--; if(mqueue.head != mqueue.tail){ mqueue.head = mqueue.head->next; } else{ mqueue.head->next = malloc(sizeof(struct message)); mqueue.head = mqueue.head->next; mqueue.head->next = malloc(sizeof(struct message)); mqueue.tail = mqueue.head->next; mqueue.head->message = NULL; } free(pointer->message); free(pointer); pthread_mutex_unlock(&numm); pthread_mutex_unlock(&circ); pthread_mutex_unlock(&slots); The messages for both threads are the same, being of the form ./path/imageXX.ppm where XX is the number that should go to the client. The file size of each image is 58368 bytes. Sometimes, this code hangs on the read, and stops execution. I don't know this would be either, because the file descriptor comes back as valid. Thanks in advanced. Edit: Here's some sample output: Sending to client a: ./support/images/sw90.ppm This is fd 4 Error: : Socket operation on non-socket Sending to client a: ./support/images/sw91.ppm This is fd 4 Error: : Socket operation on non-socket Sending ./support/images/sw92.ppm This is fd 4 I am hhere2 Error: : Socket operation on non-socket My dispatcher has defeated evil Sample with 2 clients (client b was serviced first) Sending to client b: ./support/images/sw87.ppm This is fd 6 Error: : Success Sending to client b: ./support/images/sw88.ppm This is fd 6 Error: : Success Sending to client b: ./support/images/sw89.ppm This is fd 6 Error: : Success This is fd 6 Error: : Bad file descriptor Sending to client a: ./support/images/sw85.ppm This is fd 6 Error: As you can see, who ever is serviced first in this instance can open the files, but not the 2nd person. Edit2: Full code. Sorry, its pretty long and terribly formatted. #include <netinet/in.h> #include <netinet/in.h> #include <netdb.h> #include <arpa/inet.h> #include <sys/types.h> #include <sys/socket.h> #include <errno.h> #include <stdio.h> #include <unistd.h> #include <pthread.h> #include <stdlib.h> #include <string.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include "ring.h" /* Version 1 Here is what is implemented so far: The threads are created from the arguments specified (number of threads that is) The server will lock and update variables based on how many clients are in the system and such. The socket that is opened when a new client connects, must be passed to the threads. To do this, we need some sort of global array. I did this by specifying an int client and main_pool_busy, and two pointers poolsockets and nonpoolsockets. My thinking on this was that when a new client enters the system, the server thread increments the variable client. When a thread is finished with this client (after it sends it the data), the thread will decrement client and close the socket. HTTP servers act this way sometimes (they terminate the socket as soon as one transmission is sent). *Note down at bottom After the server portion increments the client counter, we must open up a new socket (denoted by new_sd) and get this value to the appropriate thread. To do this, I created global array poolsockets, which will hold all the socket descriptors for our pooled threads. The server portion gets the new socket descriptor, and places the value in the first spot of the array that has a 0. We only place a value in this array IF: 1. The variable main_pool_busy < worknum (If we have more clients in the system than in our pool, it doesn't mean we should always create a new thread. At the end of this, the server signals on the condition variable clientin that a new client has arrived. In our pooled thread, we then must walk this array and check the array until we hit our first non-zero value. This is the socket we will give to that thread. The thread then changes the array to have a zero here. What if our all threads in our pool our busy? If this is the case, then we will know it because our threads in this pool will increment main_pool_busy by one when they are working on a request and decrement it when they are done. If main_pool_busy >= worknum, then we must dynamically create a new thread. Then, we must realloc the size of our nonpoolsockets array by 1 int. We then add the new socket descriptor to our pool. Here's what we need to figure out: NOTE* Each worker should generate 100 messages which specify the worker thread ID, client socket descriptor and a copy of the client message. Additionally, each message should include a message number, starting from 0 and incrementing for each subsequent message sent to the same client. I don't know how to keep track of how many messages were to the same client. Maybe we shouldn't close the socket descriptor, but rather keep an array of structs for each socket that includes how many messages they have been sent. Then, the server adds the struct, the threads remove it, then the threads add it back once they've serviced one request (unless the count is 100). ------------------------------------------------------------- CHANGES Version 1 ---------- NONE: this is the first version. */ #define MAXSLOTS 30 #define dis_m 15 //problems with dis_m ==1 //Function prototypes void inc_clients(); void init_mutex_stuff(pthread_t*, pthread_t*); void *threadpool(void *); void server(int); void add_to_socket_pool(int); void inc_busy(); void dec_busy(); void *dispatcher(); void create_message(long, int, int, char *, char *); void init_ring(); void add_to_ring(char *, char *, int, int, int); int socket_from_string(char *); void add_to_head(char *); void add_to_tail(char *); struct message * reorder(struct message *, struct message *, int); int get_threadid(char *); void delete_socket_messages(int); struct message * merge(struct message *, struct message *, int); int get_request(char *, char *, char*); ///////////////////// //Global mutexes and condition variables pthread_mutex_t startservice; pthread_mutex_t numclients; pthread_mutex_t pool_sockets; pthread_mutex_t nonpool_sockets; pthread_mutex_t m_pool_busy; pthread_mutex_t slots; pthread_mutex_t numm; pthread_mutex_t circ; pthread_cond_t clientin; pthread_cond_t m; /////////////////////////////////////// //Global variables int clients; int main_pool_busy; int * poolsockets, nonpoolsockets; int worknum; struct ring mqueue; /////////////////////////////////////// int main(int argc, char ** argv){ //error handling if not enough arguments to program if(argc != 3){ printf("Not enough arguments to server: ./server portnum NumThreadsinPool\n"); _exit(-1); } //Convert arguments from strings to integer values int port = atoi(argv[1]); worknum = atoi(argv[2]); //Start server portion server(port); } /////////////////////////////////////////////////////////////////////////////////////////////// //The listen server thread///////////////////////////////////////////////////////////////////// /////////////////////////////////////////////////////////////////////////////////////////////// void server(int port){ int sd, new_sd; struct sockaddr_in name, cli_name; int sock_opt_val = 1; int cli_len; pthread_t threads[worknum]; //create our pthread id array pthread_t dis[1]; //create our dispatcher array (necessary to create thread) init_mutex_stuff(threads, dis); //initialize mutexes and stuff //Server setup /////////////////////////////////////////////////////// if ((sd = socket (AF_INET, SOCK_STREAM, 0)) < 0) { perror("(servConn): socket() error"); _exit (-1); } if (setsockopt (sd, SOL_SOCKET, SO_REUSEADDR, (char *) &sock_opt_val, sizeof(sock_opt_val)) < 0) { perror ("(servConn): Failed to set SO_REUSEADDR on INET socket"); _exit (-1); } name.sin_family = AF_INET; name.sin_port = htons (port); name.sin_addr.s_addr = htonl(INADDR_ANY); if (bind (sd, (struct sockaddr *)&name, sizeof(name)) < 0) { perror ("(servConn): bind() error"); _exit (-1); } listen (sd, 5); //End of server Setup ////////////////////////////////////////////////// for (;;) { cli_len = sizeof (cli_name); new_sd = accept (sd, (struct sockaddr *) &cli_name, &cli_len); printf ("Assigning new socket descriptor: %d\n", new_sd); inc_clients(); //New client has come in, increment clients add_to_socket_pool(new_sd); //Add client to the pool of sockets if (new_sd < 0) { perror ("(servConn): accept() error"); _exit (-1); } } pthread_exit(NULL); //Quit } //Adds the new socket to the array designated for pthreads in the pool void add_to_socket_pool(int socket){ pthread_mutex_lock(&m_pool_busy); //Lock so that we can check main_pool_busy int i; //If not all our main pool is busy, then allocate to one of them if(main_pool_busy < worknum){ pthread_mutex_unlock(&m_pool_busy); //unlock busy, we no longer need to hold it pthread_mutex_lock(&pool_sockets); //Lock the socket pool array so that we can edit it without worry for(i = 0; i < worknum; i++){ //Find a poolsocket that is -1; then we should put the real socket there. This value will be changed back to -1 when the thread grabs the sockfd if(poolsockets[i] == -1){ poolsockets[i] = socket; pthread_mutex_unlock(&pool_sockets); //unlock our pool array, we don't need it anymore inc_busy(); //Incrememnt busy (locks the mutex itself) pthread_cond_signal(&clientin); //Signal first thread waiting on a client that a client needs to be serviced break; } } } else{ //Dynamic thread creation goes here pthread_mutex_unlock(&m_pool_busy); } } //Increments the client number. If client number goes over worknum, we must dynamically create new pthreads void inc_clients(){ pthread_mutex_lock(&numclients); clients++; pthread_mutex_unlock(&numclients); } //Increments busy void inc_busy(){ pthread_mutex_lock(&m_pool_busy); main_pool_busy++; pthread_mutex_unlock(&m_pool_busy); } //Initialize all of our mutexes at the beginning and create our pthreads void init_mutex_stuff(pthread_t * threads, pthread_t * dis){ pthread_mutex_init(&startservice, NULL); pthread_mutex_init(&numclients, NULL); pthread_mutex_init(&pool_sockets, NULL); pthread_mutex_init(&nonpool_sockets, NULL); pthread_mutex_init(&m_pool_busy, NULL); pthread_mutex_init(&circ, NULL); pthread_cond_init (&clientin, NULL); main_pool_busy = 0; poolsockets = malloc(sizeof(int)*worknum); int threadreturn; //error checking variables long i = 0; //Loop and create pthreads for(i; i < worknum; i++){ threadreturn = pthread_create(&threads[i], NULL, threadpool, (void *) i); poolsockets[i] = -1; if(threadreturn){ perror("Thread pool created unsuccessfully"); _exit(-1); } } pthread_create(&dis[0], NULL, dispatcher, NULL); } ////////////////////////////////////////////////////////////////////////////////////////// /////////Main pool routines ///////////////////////////////////////////////////////////////////////////////////////// void dec_busy(){ pthread_mutex_lock(&m_pool_busy); main_pool_busy--; pthread_mutex_unlock(&m_pool_busy); } void dec_clients(){ pthread_mutex_lock(&numclients); clients--; pthread_mutex_unlock(&numclients); } //This is what our threadpool pthreads will be running. void *threadpool(void * threadid){ long id = (long) threadid; //Id of this thread int i; int socket; int counter = 0; //Try and gain access to the next client that comes in and wait until server signals that a client as arrived while(1){ pthread_mutex_lock(&startservice); //lock start service (required for cond wait) pthread_cond_wait(&clientin, &startservice); //wait for signal from server that client exists pthread_mutex_unlock(&startservice); //unlock mutex. pthread_mutex_lock(&pool_sockets); //Lock the pool socket so we can get the socket fd unhindered/interrupted for(i = 0; i < worknum; i++){ if(poolsockets[i] != -1){ socket = poolsockets[i]; poolsockets[i] = -1; pthread_mutex_unlock(&pool_sockets); } } printf("Thread #%d is past getting the socket\n", id); int incoming = 1; while(counter < 100 && incoming != 0){ char buffer[512]; bzero(buffer,512); int startcounter = 0; incoming = read(socket, buffer, 512); if(buffer[0] != 0){ //client ID:priority:request:arguments char id[100]; long prior; char request[100]; char arg1[100]; char message[100]; char arg2[100]; char * point; point = strtok(buffer, ":"); strcpy(id, point); point = strtok(NULL, ":"); prior = atoi(point); point = strtok(NULL, ":"); strcpy(request, point); point = strtok(NULL, ":"); strcpy(arg1, point); point = strtok(NULL, ":"); if(point != NULL){ strcpy(arg2, point); } int fd; if(strcmp(request, "start_movie") == 0){ int count = 1; while(count <= 100){ char temp[10]; snprintf(temp, 50, "%d\0", count); strcpy(message, "./support/images/"); strcat(message, arg1); strcat(message, temp); strcat(message, ".ppm"); printf("This is message %s to %s\n", message, id); count++; add_to_ring(message, id, prior, counter, socket); //Adds our created message to the ring counter++; } printf("I'm out of the loop\n"); } else if(strcmp(request, "seek_movie") == 0){ int count = atoi(arg2); while(count <= 100){ char temp[10]; snprintf(temp, 10, "%d\0", count); strcpy(message, "./support/images/"); strcat(message, arg1); strcat(message, temp); strcat(message, ".ppm"); printf("This is message %s\n", message); count++; } } //create_message(id, socket, counter, buffer, message); //Creates our message from the input from the client. Stores it in buffer } else{ delete_socket_messages(socket); break; } } counter = 0; close(socket);//Zero out counter again } dec_clients(); //client serviced, decrement clients dec_busy(); //thread finished, decrement busy } //Creates a message void create_message(long threadid, int socket, int counter, char * buffer, char * message){ snprintf(message, strlen(buffer)+15, "%d:%d:%d:%s", threadid, socket, counter, buffer); } //Gets the socket from the message string (maybe I should just pass in the socket to another method) int socket_from_string(char * message){ char * substr1 = strstr(message, ":"); char * substr2 = substr1; substr2++; int occurance = strcspn(substr2, ":"); char sock[10]; strncpy(sock, substr2, occurance); return atoi(sock); } //Adds message to our ring buffer's head void add_to_head(char * message){ printf("Adding to head of ring\n"); mqueue.head->message = malloc(strlen(message)+1); //Allocate space for message strcpy(mqueue.head->message, message); //copy bytes into allocated space } //Adds our message to our ring buffer's tail void add_to_tail(char * message){ printf("Adding to tail of ring\n"); mqueue.tail->message = malloc(strlen(message)+1); //allocate space for message strcpy(mqueue.tail->message, message); //copy bytes into allocated space mqueue.tail->next = malloc(sizeof(struct message)); //allocate space for the next message struct } //Adds a message to our ring void add_to_ring(char * message, char * id, int prior, int mnum, int socket){ //printf("This is message %s:" , message); pthread_mutex_lock(&circ); //Lock the ring buffer pthread_mutex_lock(&numm); //Lock the message count (will need this to make sure we can't fill the buffer over the max slots) if(mqueue.head->message == NULL){ add_to_head(message); //Adds it to head mqueue.head->socket = socket; //Set message socket mqueue.head->priority = prior; //Set its priority (thread id) mqueue.head->mnum = mnum; //Set its message number (used for sorting) mqueue.head->id = malloc(sizeof(id)); strcpy(mqueue.head->id, id); } else if(mqueue.tail->message == NULL){ //This is the problem for dis_m 1 I'm pretty sure add_to_tail(message); mqueue.tail->socket = socket; mqueue.tail->priority = prior; mqueue.tail->mnum = mnum; mqueue.tail->id = malloc(sizeof(id)); strcpy(mqueue.tail->id, id); } else{ mqueue.tail->next = malloc(sizeof(struct message)); mqueue.tail = mqueue.tail->next; add_to_tail(message); mqueue.tail->socket = socket; mqueue.tail->priority = prior; mqueue.tail->mnum = mnum; mqueue.tail->id = malloc(sizeof(id)); strcpy(mqueue.tail->id, id); } mqueue.mcount++; pthread_mutex_unlock(&circ); if(mqueue.mcount >= dis_m){ pthread_mutex_unlock(&numm); pthread_cond_signal(&m); } else{ pthread_mutex_unlock(&numm); } printf("out of add to ring\n"); fflush(stdout); } ////////////////////////////////// //Dispatcher routines ///////////////////////////////// void *dispatcher(){ init_ring(); while(1){ pthread_mutex_lock(&slots); pthread_cond_wait(&m, &slots); pthread_mutex_lock(&numm); pthread_mutex_lock(&circ); printf("Dispatcher to the rescue!\n"); mqueue.head = reorder(mqueue.head, mqueue.tail, mqueue.mcount); //printf("This is the head %s\n", mqueue.head->message); //printf("This is the tail %s\n", mqueue.head->message); fflush(stdout); struct message * pointer = mqueue.head; int count = 0; while(mqueue.head != mqueue.tail && count < dis_m){ printf("Sending to client %s: %s\n", pointer->id, pointer->message); int fd; fd = open(pointer->message, O_RDONLY); char buf[58368]; int bytesRead; printf("This is fd %d\n", fd); bytesRead=read(fd,buf,58368); send(pointer->socket,buf,bytesRead,0); perror("Error:\n"); fflush(stdout); close(fd); mqueue.mcount--; mqueue.head = mqueue.head->next; free(pointer->message); free(pointer); pointer = mqueue.head; count++; } printf("Sending %s\n", pointer->message); int fd; fd = open(pointer->message, O_RDONLY); printf("This is fd %d\n", fd); printf("I am hhere2\n"); char buf[58368]; int bytesRead; bytesRead=read(fd,buf,58368); send(pointer->socket,buf,bytesRead,0); perror("Error:\n"); close(fd); mqueue.mcount--; if(mqueue.head != mqueue.tail){ mqueue.head = mqueue.head->next; } else{ mqueue.head->next = malloc(sizeof(struct message)); mqueue.head = mqueue.head->next; mqueue.head->next = malloc(sizeof(struct message)); mqueue.tail = mqueue.head->next; mqueue.head->message = NULL; } free(pointer->message); free(pointer); pthread_mutex_unlock(&numm); pthread_mutex_unlock(&circ); pthread_mutex_unlock(&slots); printf("My dispatcher has defeated evil\n"); } } void init_ring(){ mqueue.head = malloc(sizeof(struct message)); mqueue.head->next = malloc(sizeof(struct message)); mqueue.tail = mqueue.head->next; mqueue.mcount = 0; } struct message * reorder(struct message * begin, struct message * end, int num){ //printf("I am reordering for size %d\n", num); fflush(stdout); int i; if(num == 1){ //printf("Begin: %s\n", begin->message); begin->next = NULL; return begin; } else{ struct message * left = begin; struct message * right; int middle = num/2; for(i = 1; i < middle; i++){ left = left->next; } right = left -> next; left -> next = NULL; //printf("Begin: %s\nLeft: %s\nright: %s\nend:%s\n", begin->message, left->message, right->message, end->message); left = reorder(begin, left, middle); if(num%2 != 0){ right = reorder(right, end, middle+1); } else{ right = reorder(right, end, middle); } return merge(left, right, num); } } struct message * merge(struct message * left, struct message * right, int num){ //printf("I am merginging! left: %s %d, right: %s %dnum: %d\n", left->message,left->priority, right->message, right->priority, num); struct message * start, * point; int lenL= 0; int lenR = 0; int flagL = 0; int flagR = 0; int count = 0; int middle1 = num/2; int middle2; if(num%2 != 0){ middle2 = middle1+1; } else{ middle2 = middle1; } while(lenL < middle1 && lenR < middle2){ count++; //printf("In here for count %d\n", count); if(lenL == 0 && lenR == 0){ if(left->priority < right->priority){ start = left; //Set the start point point = left; //set our enum; left = left->next; //move the left pointer point->next = NULL; //Set the next node to NULL lenL++; } else if(left->priority > right->priority){ start = right; point = right; right = right->next; point->next = NULL; lenR++; } else{ if(left->mnum < right->mnum){ ////printf("This is where we are\n"); start = left; //Set the start point point = left; //set our enum; left = left->next; //move the left pointer point->next = NULL; //Set the next node to NULL lenL++; } else{ start = right; point = right; right = right->next; point->next = NULL; lenR++; } } } else{ if(left->priority < right->priority){ point->next = left; left = left->next; //move the left pointer point = point->next; point->next = NULL; //Set the next node to NULL lenL++; } else if(left->priority > right->priority){ point->next = right; right = right->next; point = point->next; point->next = NULL; lenR++; } else{ if(left->mnum < right->mnum){ point->next = left; //set our enum; left = left->next; point = point->next;//move the left pointer point->next = NULL; //Set the next node to NULL lenL++; } else{ point->next = right; right = right->next; point = point->next; point->next = NULL; lenR++; } } } if(lenL == middle1){ flagL = 1; break; } if(lenR == middle2){ flagR = 1; break; } } if(flagL == 1){ point->next = right; point = point->next; for(lenR; lenR< middle2-1; lenR++){ point = point->next; } point->next = NULL; mqueue.tail = point; } else{ point->next = left; point = point->next; for(lenL; lenL< middle1-1; lenL++){ point = point->next; } point->next = NULL; mqueue.tail = point; } //printf("This is the start %s\n", start->message); //printf("This is mqueue.tail %s\n", mqueue.tail->message); return start; } void delete_socket_messages(int a){ }

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  • Rebuilding array on 3ware 9690SA-8I

    - by Tim Jones
    I have a RAID10 (8x1TB) array on a 3ware 9690 card running on an Ubuntu 1110 server. There was a kernel update so I scheduled a reboot after which the array was inaccessible. I checked the status a drive has died in the array, but the controller has thrown the entire array into an 'inoperable' state instead of simply degraded (what's the point of the RAID now ;-). After taking out the 'dead' drive I run a quick test to find it completely functional without a bad sector to be found. I try to put the drive back in but the array still marks the disk as degraded (remembering serial number or something??) and the entire array as inoperable... So I swap it out for a known working drive (not the same capacity but higher - should still work) and initiate a rebuild with the the new drive as a replacement. This fails instantly with the error "(0x0B:0x0033): Unit busy : Failed to start Rebuild on Unit 0". The unit shouldn't be busy as it is not mounted (the card itself is listed with lshw but the array it provides is not). I'm pretty much at an impasse now, I don't understand how I can have a single drive failure on a RAID10 that makes the entire array inaccessible, degraded I could understand but inaccessible?? I don't think the controller as prior to the reboot it was completely functional.

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  • ZFS + FreeBSD + virtualbox

    - by John
    Hi, I'm configuring a FreeBSD server hosting virtualbox serving half dozen mission critical busy mail servers. I just learned ZFS, I'm quite attracted, but have a few questions: what is the CPU overhead of ZFS? I googled and found little (or no) benchmark for that. from what I learned, when ZFS updates files, it keeps the old file as snapshot, and write the updated part for the new version. However that would mean for each snapshot it keeps that require significant storage overhead. How much is this storage overhead? For example, suppose I have 2TB usable space, how much space can actually be used for the latest version of files one year later? is FreeBSD with ZFS hosting virtualbox serving half dozen busy guest mission critical mail servers a reasonable combination? Anything particular to be careful with? And can I still choose ZFS for the guest OSs? This is because I may build another identical such box for redundancy, and will need to do some mirroring between each pair of the guest systems across the boxes. I'm trying to configure a Dell R710 for this. From what I learned, I shouldn't choose any RAID at all, is that true? In that case, are the drives still arrive hot swappable? this may sounds a bit pathetic, but since I have no experience with ZFS at all, and this is a mission critical server, so just ask just in case: I'm choosing twin Intel L5630 processors, and 6 x 600GB 15K RPM Serial-Attach SCSI drives. If I need more space in the future, I would just hot swap some drivers with larger capacity to expand the storage. There is no problem with these, right?

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  • How to let MSN or Yahoo Messenger set you to be Invisible or Offline when you are idle for an hour?

    - by Jian Lin
    The short question is: How do we let MSN or Yahoo Messenger set us to be Invisible or Offline when we are idle for half an hour or an hour? The reason is: if I am on 24 hours a day, some people see me as weird. Some people see my value as low, because I am always there. There are ways to set me to "Away" or "Busy" after 10 minutes, but there seems to be no way to set myself to invisible or offline after 1 hour. As I am a software developer, I am very used to turning the computer on 24 hours a day. (for example, for checking email for urgent fixes, and fix issue and push to web server). We don't turn off computer usually even when we sleep, because we may sometimes can't sleep yet and come check on the computer, or wake up in the morning and immediately need to check if everything is ok. But, my MSN and Yahoo Messenger is always on for 24 hours a day, and I found that some girls start to ask me why I am always there 24 hours a day (even though they see me as away or busy, their feeling is that I am always there). What's more, I found that since I am always there, my value actually drop in their eyes, because hard to get = high value, and always there = low value. Some people feel me as having nothing much to do, always in front of computer, or what is he doing in front of computer so much? Now since it is my job, and I need to read emails once in a while, I am in fact in front of the computer more than some other people. I am in front of the computer maybe 10 hours a day, far from 24 hours a day. Is there an easy and automatic solution to this?

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  • 100% iowait + drive faults in dmesg

    - by w00t
    Hi, I have a server on which resides a fairly visited web app. It has a raid1 of 2 HDDs, 64MB Buffer, 7200 RPM. Today it started throwing out errors like: kernel: ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen kernel: ata2.00: cmd b0/d0:01:00:4f:c2/00:00:00:00:00/00 tag 0 pio 512 in kernel: res 40/00:00:00:4f:c2/00:00:00:00:00/00 Emask 0x4 (timeout) kernel: ata2.00: status: { DRDY } kernel: ata2: hard resetting link kernel: ata2: SATA link up 3.0 Gbps (SStatus 123 SControl 300) kernel: ata2.00: max_sectors limited to 256 for NCQ kernel: ata2.00: max_sectors limited to 256 for NCQ kernel: ata2.00: configured for UDMA/133 kernel: sd 1:0:0:0: timing out command, waited 7s kernel: ata2: EH complete kernel: SCSI device sda: 976773168 512-byte hdwr sectors (500108 MB) kernel: sda: Write Protect is off kernel: SCSI device sda: drive cache: write back All day long it has been in load higher than 10-15. I am monitoring it with atop and it gives some bizarre readings: DSK | sda | busy 100% | read 2 | write 208 | KiB/r 16 | KiB/w 32 | MBr/s 0.00 | MBw/s 0.65 | avq 86.17 | avio 47.6 ms | DSK | sdb | busy 1% | read 10 | write 117 | KiB/r 17 | KiB/w 5 | MBr/s 0.02 | MBw/s 0.07 | avq 4.86 | avio 1.04 ms | I frankly don't understand why only sda is taking all the hit. I do have one process that is constantly writing with 1-2megs but what the hell.. 100% iowait?

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  • How can I connect integrated webcam with virtualbox

    - by Mike Stumpf
    I am trying to use a Windows XP VM for VirtualBox on my Windows 8.1 laptop. I have tried the usual attaching USB device but I get an error saying "USB device is busy with previous request". My webcam is not active in any applications and this happens after a clean reboot of the host, the guest, and VirtualBox. Here are the details: Host -HP Pavilion 17 Notebook PC (stock) -Windows 8.1 -AMD A10-5750M APU -HP Truevision HD (integrated webcam) VM I got the VM here: http://www.modern.ie/en-us/virtualization-tools VirtualBox -VirtualBox 4.3.12 installed -VirtualBox Extension pack installed -Guest additions are installed for 4.3.12 -Enable USB Controller is checked -It does not matter if enable 2.0 controller is checked or not -It does not matter if a USB device filter is set up for the webcam or not -Here is the error message: Failed to attach the USB device DDFEQ01G45BFBV HP Truevision HD [0004] to the virtual machine IE8 - WinXP. USB device 'DDFEQ01G45BFBV HP Truevision HD' with UUID {7a2e2a45-974d-482b-9b4e-9f9abbcd0ebb} is busy with a previous request. Please try again later. Result Code: E_INVALIDARG (0x80070057) Component: HostUSBDevice Interface: IHostUSBDevice {173b4b44-d268-4334-a00d-b6521c9a740a} Callee: IConsole {8ab7c520-2442-4b66-8d74-4ff1e195d2b6} I read on some VirtualBox forums that disabling USB 2.0 support in the host BIOS solved their issue but I wanted to know if there were any other ideas before I muck around in there. Thanks

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  • Share Exchange Calendar Outside Organization

    - by CalCurious
    I'm trying to figure out the best way to meet a user's (Corp-A-User) request to share their calendar with someone at another company (Corp-B-User). We're running Microsoft SBS 2008 with Exchange 2007 and SharePoint. The remote user is running Exchange, version unknown. Corp-A-User wants to give the Corp-B-User the ability to create appointments on Corp-A-User's calendar. This will naturally require sharing of Free/Busy information. Corp-A-User naturally lacks the vision to seen ANY problem with giving Corp-B-User full access to their calendar. But, I see the problems with that and would prefer that Corp-B-User have only the ability to see Free/Busy and create appointments. Most of the external publishing options that I have thought of, such as WebDav, allow displaying a user's calendar, but there are problems with security and the ability to create appointments. Right now, I'm thinking the cleanest solution would be to use a Google calendar along with Google Calendar Sync for the two user's Outlook clients. But, I'm not sure if there isn't a better way and I hate teh idea of pushing a corporate calendar up to Google. Not to mention the issues likely to pop up from the multiple sync paths. Does any one have a good solution for this scenario that would be willing to share what they use?

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  • How to re-add a RAID-10 failed drive on Ubuntu?

    - by thiesdiggity
    I have a problem that I can't seem to solve. We have a Ubuntu server setup with RAID-10 and two of the drives dropped out of the array. When I try to re-add them using the following command: mdadm --manage --re-add /dev/md2 /dev/sdc1 I get the following error message: mdadm: Cannot open /dev/sdc1: Device or resource busy When I do a "cat /proc/mdstat" I get the following: Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [r$ md2 : active raid10 sdb1[0] sdd1[3] 1953519872 blocks 64K chunks 2 near-copies [4/2] [U__U] md1 : active raid1 sda2[0] sdc2[1] 468853696 blocks [2/2] [UU] md0 : active raid1 sda1[0] sdc1[1] 19530688 blocks [2/2] [UU] unused devices: <none> When I run "/sbin/mdadm --detail /dev/md2" I get the following: /dev/md2: Version : 00.90 Creation Time : Mon Sep 5 23:41:13 2011 Raid Level : raid10 Array Size : 1953519872 (1863.02 GiB 2000.40 GB) Used Dev Size : 976759936 (931.51 GiB 1000.20 GB) Raid Devices : 4 Total Devices : 2 Preferred Minor : 2 Persistence : Superblock is persistent Update Time : Thu Oct 25 09:25:08 2012 State : active, degraded Active Devices : 2 Working Devices : 2 Failed Devices : 0 Spare Devices : 0 Layout : near=2, far=1 Chunk Size : 64K UUID : c6d87d27:aeefcb2e:d4453e2e:0b7266cb Events : 0.6688691 Number Major Minor RaidDevice State 0 8 17 0 active sync /dev/sdb1 1 0 0 1 removed 2 0 0 2 removed 3 8 49 3 active sync /dev/sdd1 Output of df -h is: Filesystem Size Used Avail Use% Mounted on /dev/md1 441G 2.0G 416G 1% / none 32G 236K 32G 1% /dev tmpfs 32G 0 32G 0% /dev/shm none 32G 112K 32G 1% /var/run none 32G 0 32G 0% /var/lock none 32G 0 32G 0% /lib/init/rw tmpfs 64G 215M 63G 1% /mnt/vmware none 441G 2.0G 416G 1% /var/lib/ureadahead/debugfs /dev/mapper/RAID10VG-RAID10LV 1.8T 139G 1.6T 8% /mnt/RAID10 When I do a "fdisk -l" I can see all the drives needed for the RAID-10. The RAID-10 is part of the /dev/mapper, could that be the reason why the device is coming back as busy? Anyone have any suggestions on what I can try to get the drives back into the array? Any help would be greatly appreciated. Thanks!

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  • How to keep subtree removal (`rm -rf`) from starving other processes for Disk I/O?

    - by David Eyk
    We have a very large (multi-GB) Nginx cache directory for a busy site, which we occasionally need to clear all at once. I've solved this in the past by moving the cache folder to a new path, making a new cache folder at the old path, and then rm -rfing the old cache folder. Lately, however, when I need to clear the cache on a busy morning, the I/O from rm -rf is starving my server processes of disk access, as both Nginx and the server it fronts for are read-intensive. I can watch the load average climb while the CPUs sit idle and rm -rf takes 98-99% of Disk IO in iotop. I've tried ionice -c 3 when invoking rm, but it seems to have no appreciable effect on the observed behavior. Is there any way to tame rm -rf to share the disk more? Do I need to use a different technique that will take its cues from ionice? Update: The filesystem in question is an AWS EC2 instance store (the primary disk is EBS). The /etc/fstab entry looks like this: /dev/xvdb /mnt auto defaults,nobootwait,comment=cloudconfig 0 2

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  • SQL SERVER – Introduction to Extended Events – Finding Long Running Queries

    - by pinaldave
    The job of an SQL Consultant is very interesting as always. The month before, I was busy doing query optimization and performance tuning projects for our clients, and this month, I am busy delivering my performance in Microsoft SQL Server 2005/2008 Query Optimization and & Performance Tuning Course. I recently read white paper about Extended Event by SQL Server MVP Jonathan Kehayias. You can read the white paper here: Using SQL Server 2008 Extended Events. I also read another appealing chapter by Jonathan in the book, SQLAuthority Book Review – Professional SQL Server 2008 Internals and Troubleshooting. After reading these excellent notes by Jonathan, I decided to upgrade my course and include Extended Event as one of the modules. This week, I have delivered Extended Events session two times and attendees really liked the said course. They really think Extended Events is one of the most powerful tools available. Extended Events can do many things. I suggest that you read the white paper I mentioned to learn more about this tool. Instead of writing a long theory, I am going to write a very quick script for Extended Events. This event session captures all the longest running queries ever since the event session was started. One of the many advantages of the Extended Events is that it can be configured very easily and it is a robust method to collect necessary information in terms of troubleshooting. There are many targets where you can store the information, which include XML file target, which I really like. In the following Events, we are writing the details of the event at two locations: 1) Ringer Buffer; and 2) XML file. It is not necessary to write at both places, either of the two will do. -- Extended Event for finding *long running query* IF EXISTS(SELECT * FROM sys.server_event_sessions WHERE name='LongRunningQuery') DROP EVENT SESSION LongRunningQuery ON SERVER GO -- Create Event CREATE EVENT SESSION LongRunningQuery ON SERVER -- Add event to capture event ADD EVENT sqlserver.sql_statement_completed ( -- Add action - event property ACTION (sqlserver.sql_text, sqlserver.tsql_stack) -- Predicate - time 1000 milisecond WHERE sqlserver.sql_statement_completed.duration > 1000 ) -- Add target for capturing the data - XML File ADD TARGET package0.asynchronous_file_target( SET filename='c:\LongRunningQuery.xet', metadatafile='c:\LongRunningQuery.xem'), -- Add target for capturing the data - Ring Bugger ADD TARGET package0.ring_buffer (SET max_memory = 4096) WITH (max_dispatch_latency = 1 seconds) GO -- Enable Event ALTER EVENT SESSION LongRunningQuery ON SERVER STATE=START GO -- Run long query (longer than 1000 ms) SELECT * FROM AdventureWorks.Sales.SalesOrderDetail ORDER BY UnitPriceDiscount DESC GO -- Stop the event ALTER EVENT SESSION LongRunningQuery ON SERVER STATE=STOP GO -- Read the data from Ring Buffer SELECT CAST(dt.target_data AS XML) AS xmlLockData FROM sys.dm_xe_session_targets dt JOIN sys.dm_xe_sessions ds ON ds.Address = dt.event_session_address JOIN sys.server_event_sessions ss ON ds.Name = ss.Name WHERE dt.target_name = 'ring_buffer' AND ds.Name = 'LongRunningQuery' GO -- Read the data from XML File SELECT event_data_XML.value('(event/data[1])[1]','VARCHAR(100)') AS Database_ID, event_data_XML.value('(event/data[2])[1]','INT') AS OBJECT_ID, event_data_XML.value('(event/data[3])[1]','INT') AS object_type, event_data_XML.value('(event/data[4])[1]','INT') AS cpu, event_data_XML.value('(event/data[5])[1]','INT') AS duration, event_data_XML.value('(event/data[6])[1]','INT') AS reads, event_data_XML.value('(event/data[7])[1]','INT') AS writes, event_data_XML.value('(event/action[1])[1]','VARCHAR(512)') AS sql_text, event_data_XML.value('(event/action[2])[1]','VARCHAR(512)') AS tsql_stack, CAST(event_data_XML.value('(event/action[2])[1]','VARCHAR(512)') AS XML).value('(frame/@handle)[1]','VARCHAR(50)') AS handle FROM ( SELECT CAST(event_data AS XML) event_data_XML, * FROM sys.fn_xe_file_target_read_file ('c:\LongRunningQuery*.xet', 'c:\LongRunningQuery*.xem', NULL, NULL)) T GO -- Clean up. Drop the event DROP EVENT SESSION LongRunningQuery ON SERVER GO Just run the above query, afterwards you will find following result set. This result set contains the query that was running over 1000 ms. In our example, I used the XML file, and it does not reset when SQL services or computers restarts (if you are using DMV, it will reset when SQL services restarts). This event session can be very helpful for troubleshooting. Let me know if you want me to write more about Extended Events. I am totally fascinated with this feature, so I’m planning to acquire more knowledge about it so I can determine its other usages. Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Training, SQLServer, T SQL, Technology Tagged: SQL Extended Events

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  • Make Your Mouse Pointers Left-hand Friendly

    - by Matthew Guay
    It’s a right-centric world, with everything from pencils to computer mice expecting you to be right-handed.  Here’s how you can train your mouse and cursors in Windows 7 and Vista to respect your left-handedness. Using your Left Hand the Right Way It’s easy to switch your mouse to left-handed mode.  Enter “mouse” in your Start menu search, and select the first entry. Check the “Switch primary and secondary buttons” box to make your mouse more left-hand friendly.  Now your primary select button is your right button, and the secondary button (commonly referred to as right-click) is the left button. But, it can still be awkward to select items on screen with your left hand using the default cursors.  MSDN has a free set of cursors designed for left-handed users, that can fix this problem for you.  These cursors are exactly like the default Aero cursors in Windows 7 and Vista, except they are reversed to make them better for left-handed use. The cursors are available in 3 sizes: normal, large, and extra large.  The normal ones are the same size as the default ones in Windows 7; feel free to choose the other sizes if you prefer them.  Click each link to download all 6 cursors for your size (link below). Click “I Agree” after selecting the cursors to accept the license agreement and download them. Once you have all 6 cursors downloaded, select the Pointers tab in the Mouse Properties dialog.  Click the cursor to change, and then click Browse to select the new cursor. Browse to the folder you downloaded your new cursors to, select the correct cursor, and click Open. Do this for each of the 6 cursors to be changed.  Strangely, the Busy cursor (the spinning blue orb) is a static cursor, so you may not wish to change it.  All the other ones look and act like their standard counterparts. Here’s the cursors to be changed, and their equivalents in the default cursors: Normal Select: aero_arrow_left.cur Help Select: aero_helpsel_left.cur Working in Background: aero_working_left.ani Busy: aero_busy_left.cur Handwriting: aero_pen_left.cur Link Select: aero_link_left.cur After changing all the cursors, click Save As… to save this mouse scheme so you can easily select it in the future.  Finally click Ok to close the Mouse Properties dialog and accept the changes. Now your pointers will be easier to use left-handed! Conclusion Whether you’re right-handed or left-handed, you can enjoy the Aero cursors in Windows 7 or Vista in the way that works best for you.  Unfortunately, many mice are still designed for right-handed people, but this trick will help you make the best out of your mouse. We included all of the 6 cursors for you in a zip file you can download Here. This will make it easier for you to get them all together without having to download them individually. Link Download Left-Handed Mouse Pointers from MSDN Similar Articles Productive Geek Tips Prevent Themes From Modifying Icons and Cursors in Windows 7How To Personalize Windows 7 StarterShow Two Time Zones in Your Outlook 2007 CalendarMake Mouse Navigation Faster in WindowsWhy Doesn’t Tab Work for Drop-down Controls in Firefox on OS X? TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 Microsoft’s “How Do I ?” Videos Home Networks – How do they look like & the problems they cause Check Your IMAP Mail Offline In Thunderbird Follow Finder Finds You Twitter Users To Follow Combine MP3 Files Easily QuicklyCode Provides Cheatsheets & Other Programming Stuff

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  • ArchBeat Top 10 for December 2-8, 2012

    - by Bob Rhubart
    The Top 10 most-clicked items shared on the OTN ArchBeat Facebook page for the week of December 2-8, 2012 Configure Oracle SOA JMSAdatper to Work with WLS JMS Topics Another of the four posts published on Dec 4 by the Fusion Middleware A-Team blogger identified as "fip" illlustrates "how to configure the JMS Topic, the JmsAdapter connection factory, as well as the composite so that the JMS Topic messages will be evenly distributed to same composite running off different SOA cluster nodes without causing duplication." Web Service Example - Part 3: Asynchronous Part 3 in this series from the Oracle ADF Mobile blog looks at "firing the web service asynchronously and then filling in the UI when it completes." Denis says, "This can be useful when you have data on the device in a local store and want to show that to the user while the application uses lazy loading from a web service to load more data." Advanced Oracle SOA Suite Oracle Open World 2012 SOA Presentations Oracle SOA & BPM Partner Community blogger Juergen Kress shares a list of 13 SOA presentations delivered or moderated by Oracle SOA Product Management at OOW12 in San Francisco. Oracle WebLogic Server WLS Domain Browser My colleague Jeff Davies, a frequent speaker at OTN Architect Day events and a genuinely nice guy, emailed me last night with this message: "I just came across this app on Google Play. It allows WebLogic administrators to browse WLS 12c domain information. I installed it on my phone and tried it out. Works very fast." I'm an iPhone guy, but I'm perfectly comfortable taking Jeff at his word. The app is called WLS Domain Browser. Follow the link for more info from the Google Play site. Retrieve Performance Data from SOA Infrastructure Database Another of the four blog posts published on Dec 4 by very busy Oracle Fusion Middleware A-Team member "fip," this one offers "examples of some basic SQL queries you can run against the infrastructure database of Oracle SOA Suite 11G to acquire the performance statistics for a given period of time." How to Achieve OC4J RMI Load Balancing "Having returned from a customer who faced challenges with OC4J RMI load balancing, I felt there is still some confusion in the field [about] how OC4J RMI load balancing works," says the Oracle Fusion Middleware A-Team member known only as "fip." "Hence I decide to dust off an old tech note that I wrote a few years back and share it with the general public." From XaaS to Java EE – Which damn cloud is right for me in 2012? Oracle ACE Director Markus Eisele wrestles with a timely technical issue and shares his observations on several of the alternatives. Exalogic 2.0.1 Tea Break Snippets - Creating a ModifyJeOS VirtualBox "One of the main advantages of this is that Templates can be created away from the Exalogic Environment," explains The Old Toxophilist. (BTW: I had to look it up: a toxophilist is one who collects bows and arrows.) ADF Mobile - Implementing Reusable Mobile Architecture "Reusability was always a strong part of ADF," says Oracle ACE Director Andrejus Baranovskis. "The same high reusability level is supported now in ADF Mobile." The objective of this post is "to prove technically that [the] reusable architecture concept works for ADF Mobile." Using BPEL Performance Statistics to Diagnose Performance Bottlenecks Someone had a busy day… This post, one of four published on DeC 4 by a member of the Oracle Fusion Middleware A-Team identified only as "fip," offers details on how to "enable, retrieve and interpret the performance statistics, before the future versions provides a more pleasant user experience." Thought for the Day "If you're afraid to change something it is clearly poorly designed." — Martin Fowler Source: SoftwareQuotes.com

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  • Oracle WebLogic Server and Oracle Database: A Robust Infrastructure for your Applications

    - by Ruma Sanyal
    Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 It has been said that a chain is as strong as its weakest link. Well, this is also true for your application infrastructure. Not only are the various components that constitute your infrastructure, like database and application server critical, the integration between these things [whether coming out of the box from your vendor or done in-house] is paramount. Imagine your database being down and your application server not knowing about it and as a result your application waiting indefinitely for a database response – not a great situation if high availability is critical to your application. Or one of your database nodes is very busy, but your application server doesn’t have the intelligence to decipher that – it keeps pinging the busy node when it can in fact get a response from another idle node much faster. This is what Oracle WebLogic and Database integration provides: Intelligent integration out of the box. Tight integration between Oracle WebLogic and Database makes your infrastructure robust enough that not only does each of your infrastructure component provide you with improved RASP [reliability availability, scalability, and performance] but these components work together to offer improved performance & availability, better resource sharing, inherent scalability, ease of configuration and automated management for your entire infrastructure. Oracle WebLogic Server is the only application server with this degree of integration to Oracle Database. With Oracle WebLogic Server 11g, we introduced Active GridLink for Real Application Clusters (RAC). In conjunction with Oracle Database, this powerful software technology simplifies management, increases availability, and ensures fast connection failover with runtime connection, load balancing and affinity capabilities. With the release of Oracle Database 12c this summer, even tighter integration between Oracle WebLogic Server 12c (12.1.2) and Oracle Database 12c has been achieved and this further optimizes the integration for a global cloud environment. Read about these capabilities in detail in the Oracle WebLogic-Database Integration Whitepaper. Get in depth ‘how-to’ details from this YouTube video on the topic from our resident expert, Monica Roccelli. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

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  • SQL Server IO handling mechanism can be severely affected by high CPU usage

    - by sqlworkshops
    Are you using SSD or SAN / NAS based storage solution and sporadically observe SQL Server experiencing high IO wait times or from time to time your DAS / HDD becomes very slow according to SQL Server statistics? Read on… I need your help to up vote my connect item – https://connect.microsoft.com/SQLServer/feedback/details/744650/sql-server-io-handling-mechanism-can-be-severely-affected-by-high-cpu-usage. Instead of taking few seconds, queries could take minutes/hours to complete when CPU is busy.In SQL Server when a query / request needs to read data that is not in data cache or when the request has to write to disk, like transaction log records, the request / task will queue up the IO operation and wait for it to complete (task in suspended state, this wait time is the resource wait time). When the IO operation is complete, the task will be queued to run on the CPU. If the CPU is busy executing other tasks, this task will wait (task in runnable state) until other tasks in the queue either complete or get suspended due to waits or exhaust their quantum of 4ms (this is the signal wait time, which along with resource wait time will increase the overall wait time). When the CPU becomes free, the task will finally be run on the CPU (task in running state).The signal wait time can be up to 4ms per runnable task, this is by design. So if a CPU has 5 runnable tasks in the queue, then this query after the resource becomes available might wait up to a maximum of 5 X 4ms = 20ms in the runnable state (normally less as other tasks might not use the full quantum).In case the CPU usage is high, let’s say many CPU intensive queries are running on the instance, there is a possibility that the IO operations that are completed at the Hardware and Operating System level are not yet processed by SQL Server, keeping the task in the resource wait state for longer than necessary. In case of an SSD, the IO operation might even complete in less than a millisecond, but it might take SQL Server 100s of milliseconds, for instance, to process the completed IO operation. For example, let’s say you have a user inserting 500 rows in individual transactions. When the transaction log is on an SSD or battery backed up controller that has write cache enabled, all of these inserts will complete in 100 to 200ms. With a CPU intensive parallel query executing across all CPU cores, the same inserts might take minutes to complete. WRITELOG wait time will be very high in this case (both under sys.dm_io_virtual_file_stats and sys.dm_os_wait_stats). In addition you will notice a large number of WAITELOG waits since log records are written by LOG WRITER and hence very high signal_wait_time_ms leading to more query delays. However, Performance Monitor Counter, PhysicalDisk, Avg. Disk sec/Write will report very low latency times.Such delayed IO handling also occurs to read operations with artificially very high PAGEIOLATCH_SH wait time (with number of PAGEIOLATCH_SH waits remaining the same). This problem will manifest more and more as customers start using SSD based storage for SQL Server, since they drive the CPU usage to the limits with faster IOs. We have a few workarounds for specific scenarios, but we think Microsoft should resolve this issue at the product level. We have a connect item open – https://connect.microsoft.com/SQLServer/feedback/details/744650/sql-server-io-handling-mechanism-can-be-severely-affected-by-high-cpu-usage - (with example scripts) to reproduce this behavior, please up vote the item so the issue will be addressed by the SQL Server product team soon.Thanks for your help and best regards,Ramesh MeyyappanHome: www.sqlworkshops.comLinkedIn: http://at.linkedin.com/in/rmeyyappan

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  • Spotlight on an office – Utrecht

    - by Maria Sandu
    Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-family:"Calibri","sans-serif"; mso-ascii- mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi- mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} This time in our monthly topic, we have our spotlight on the brand new Oracle office in Utrecht, the Netherlands. About 35km south-east of Schiphol Airport and centrally located in the Netherlands, Oracle moved into the Facet building in March 2011. Facet is much more than an office building, it creates a work environment that relates to the ‘No Limits’ philosophy Oracle has in the Netherlands. “No Limits” means the building belongs to everyone. You choose the best place to work, based on the activities of that moment. To point this out, we currently have 1050 people working for Oracle Netherlands, and 623 workplaces. There is virtually no limit to where you can sit in our shiny new offices; we no longer have 'zoning', where departments own specific areas in the building, Even the Managing Director of Oracle Netherlands, does not have an office and he chooses a different working place every day. So make sure you are prepared when he is sitting next to you one day! If nobody has a fixed workplace, then you would think that finding a colleague could be tricky. Oracle uses CU (‘SeeYou’) which makes all of us easier to locate. Upon entering the building you receive a text stating where the greatest concentration of your buddies is sitting. Our internal messaging service also proves to be very valuable finding your colleagues. The heart of our building is the great RestOrant, with a very busy coffee bar. It offers an informal place for people to meet and is busy all day, not just at lunch time! The O-Bar in the atrium on the ground floor is also a very popular place to meet and drink tea or coffee and gives a breathtaking introduction to the office to any of our first time visitors. For a few minutes of relaxation during the working day, there are table tennis facilities and a Wii room on every floor! So if you are interested in joining Oracle in this Netherlands or anywhere else in EMEA, please have a look at http://campus.oracle.com for all of our latest vacancies and internships.

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  • Using Audio Queue Services to play PCM data over a socket connection

    - by Rohan
    I'm writing a remote desktop client for the iPhone and I'm trying to implement audio redirection. The client is connected to the server over a socket connection, and the server sends 32K chunks of PCM data at a time. I'm trying to use AQS to play the data and it plays the first two seconds (1 buffer worth). However, since the next chunk of data hasn't come in over the socket yet, the next AudioQueueBuffer is empty. When the data comes in, I fill the next available buffer with the data and enqueue it with AudioQueueEnqueueBuffer. However, it never plays these buffers. Does the queue stop playing if there are no buffers in the queue, even if you later add a buffer? Here's the relevant part of the code: void wave_out_write(STREAM s, uint16 tick, uint8 index) { if(items_in_queue == NUM_BUFFERS){ return; } if(!playState.busy){ OSStatus status; status = AudioQueueNewOutput(&playState.dataFormat, AudioOutputCallback, &playState, CFRunLoopGetCurrent(), NULL, 0, &playState.queue); if(status == 0){ for(int i=0; i<NUM_BUFFERS; i++){ AudioQueueAllocateBuffer(playState.queue, 40000, &playState.buffers[i]); } AudioQueueAddPropertyListener(playState.queue, kAudioQueueProperty_IsRunning, MyAudioQueuePropertyListenerProc, &playState); status = AudioQueueStart(playState.queue, NULL); if(status ==0){ playState.busy = True; } else{ return; } } else{ return; } } playState.buffers[queue_hi]->mAudioDataByteSize = s->size; memcpy(playState.buffers[queue_hi]->mAudioData, s->data, s->size); AudioQueueEnqueueBuffer(playState.queue, playState.buffers[queue_hi], 0, 0); queue_hi++; queue_hi = queue_hi % NUM_BUFFERS; items_in_queue++; } void AudioOutputCallback(void* inUserData, AudioQueueRef outAQ, AudioQueueBufferRef outBuffer) { PlayState *playState = (PlayState *)inUserData; items_in_queue--; } Thanks!

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