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  • Raid1 with active and spare partition

    - by Daniel Baron
    I am having the following problem with a RAID1 software raid partition on my Ubuntu system (10.04 LTS, 2.6.32-24-server in case it matters). One of my disks (sdb5) reported I/O errors and was therefore marked faulty in the array. The array was then degraded with one active device. Hence, I replaced the harddisk, cloned the partition table and added all new partitions to my raid arrays. After syncing all partitions ended up fine, having 2 active devices - except one of them. The partition which reported the faulty disk before, however, did not include the new partition as an active device but as a spare disk: md3 : active raid1 sdb5[2] sda5[1] 4881344 blocks [2/1] [_U] A detailed look reveals: root@server:~# mdadm --detail /dev/md3 [...] Number Major Minor RaidDevice State 2 8 21 0 spare rebuilding /dev/sdb5 1 8 5 1 active sync /dev/sda5 So here is the question: How do I tell my raid to turn the spare disk into an active one? And why has it been added as a spare device? Recreating or reassembling the array is not an option, because it is my root partition. And I can not find any hints to that subject in the Software Raid HOWTO. Any help would be appreciated. Current Solution I found a solution to my problem, but I am not sure that this is the actual way to do it. Having a closer look at my raid I found that sdb5 was always listed as a spare device: mdadm --examine /dev/sdb5 [...] Number Major Minor RaidDevice State this 2 8 21 2 spare /dev/sdb5 0 0 0 0 0 removed 1 1 8 5 1 active sync /dev/sda5 2 2 8 21 2 spare /dev/sdb5 so readding the device sdb5 to the array md3 always ended up in adding the device as a spare. Finally I just recreated the array mdadm --create /dev/md3 --level=1 -n2 -x0 /dev/sda5 /dev/sdb5 which worked. But the question remains open for me: Is there a better way to manipulate the summaries in the superblock and to tell the array to turn sdb5 from a spare disk to an active disk? I am still curious for an answer.

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  • Organization &amp; Architecture UNISA Studies &ndash; Chap 4

    - by MarkPearl
    Learning Outcomes Explain the characteristics of memory systems Describe the memory hierarchy Discuss cache memory principles Discuss issues relevant to cache design Describe the cache organization of the Pentium Computer Memory Systems There are key characteristics of memory… Location – internal or external Capacity – expressed in terms of bytes Unit of Transfer – the number of bits read out of or written into memory at a time Access Method – sequential, direct, random or associative From a users perspective the two most important characteristics of memory are… Capacity Performance – access time, memory cycle time, transfer rate The trade off for memory happens along three axis… Faster access time, greater cost per bit Greater capacity, smaller cost per bit Greater capacity, slower access time This leads to people using a tiered approach in their use of memory   As one goes down the hierarchy, the following occurs… Decreasing cost per bit Increasing capacity Increasing access time Decreasing frequency of access of the memory by the processor The use of two levels of memory to reduce average access time works in principle, but only if conditions 1 to 4 apply. A variety of technologies exist that allow us to accomplish this. Thus it is possible to organize data across the hierarchy such that the percentage of accesses to each successively lower level is substantially less than that of the level above. A portion of main memory can be used as a buffer to hold data temporarily that is to be read out to disk. This is sometimes referred to as a disk cache and improves performance in two ways… Disk writes are clustered. Instead of many small transfers of data, we have a few large transfers of data. This improves disk performance and minimizes processor involvement. Some data designed for write-out may be referenced by a program before the next dump to disk. In that case the data is retrieved rapidly from the software cache rather than slowly from disk. Cache Memory Principles Cache memory is substantially faster than main memory. A caching system works as follows.. When a processor attempts to read a word of memory, a check is made to see if this in in cache memory… If it is, the data is supplied, If it is not in the cache, a block of main memory, consisting of a fixed number of words is loaded to the cache. Because of the phenomenon of locality of references, when a block of data is fetched into the cache, it is likely that there will be future references to that same memory location or to other words in the block. Elements of Cache Design While there are a large number of cache implementations, there are a few basic design elements that serve to classify and differentiate cache architectures… Cache Addresses Cache Size Mapping Function Replacement Algorithm Write Policy Line Size Number of Caches Cache Addresses Almost all non-embedded processors support virtual memory. Virtual memory in essence allows a program to address memory from a logical point of view without needing to worry about the amount of physical memory available. When virtual addresses are used the designer may choose to place the cache between the MMU (memory management unit) and the processor or between the MMU and main memory. The disadvantage of virtual memory is that most virtual memory systems supply each application with the same virtual memory address space (each application sees virtual memory starting at memory address 0), which means the cache memory must be completely flushed with each application context switch or extra bits must be added to each line of the cache to identify which virtual address space the address refers to. Cache Size We would like the size of the cache to be small enough so that the overall average cost per bit is close to that of main memory alone and large enough so that the overall average access time is close to that of the cache alone. Also, larger caches are slightly slower than smaller ones. Mapping Function Because there are fewer cache lines than main memory blocks, an algorithm is needed for mapping main memory blocks into cache lines. The choice of mapping function dictates how the cache is organized. Three techniques can be used… Direct – simplest technique, maps each block of main memory into only one possible cache line Associative – Each main memory block to be loaded into any line of the cache Set Associative – exhibits the strengths of both the direct and associative approaches while reducing their disadvantages For detailed explanations of each approach – read the text book (page 148 – 154) Replacement Algorithm For associative and set associating mapping a replacement algorithm is needed to determine which of the existing blocks in the cache must be replaced by a new block. There are four common approaches… LRU (Least recently used) FIFO (First in first out) LFU (Least frequently used) Random selection Write Policy When a block resident in the cache is to be replaced, there are two cases to consider If no writes to that block have happened in the cache – discard it If a write has occurred, a process needs to be initiated where the changes in the cache are propagated back to the main memory. There are several approaches to achieve this including… Write Through – all writes to the cache are done to the main memory as well at the point of the change Write Back – when a block is replaced, all dirty bits are written back to main memory The problem is complicated when we have multiple caches, there are techniques to accommodate for this but I have not summarized them. Line Size When a block of data is retrieved and placed in the cache, not only the desired word but also some number of adjacent words are retrieved. As the block size increases from very small to larger sizes, the hit ratio will at first increase because of the principle of locality, which states that the data in the vicinity of a referenced word are likely to be referenced in the near future. As the block size increases, more useful data are brought into cache. The hit ratio will begin to decrease as the block becomes even bigger and the probability of using the newly fetched information becomes less than the probability of using the newly fetched information that has to be replaced. Two specific effects come into play… Larger blocks reduce the number of blocks that fit into a cache. Because each block fetch overwrites older cache contents, a small number of blocks results in data being overwritten shortly after they are fetched. As a block becomes larger, each additional word is farther from the requested word and therefore less likely to be needed in the near future. The relationship between block size and hit ratio is complex, and no set approach is judged to be the best in all circumstances.   Pentium 4 and ARM cache organizations The processor core consists of four major components: Fetch/decode unit – fetches program instruction in order from the L2 cache, decodes these into a series of micro-operations, and stores the results in the L2 instruction cache Out-of-order execution logic – Schedules execution of the micro-operations subject to data dependencies and resource availability – thus micro-operations may be scheduled for execution in a different order than they were fetched from the instruction stream. As time permits, this unit schedules speculative execution of micro-operations that may be required in the future Execution units – These units execute micro-operations, fetching the required data from the L1 data cache and temporarily storing results in registers Memory subsystem – This unit includes the L2 and L3 caches and the system bus, which is used to access main memory when the L1 and L2 caches have a cache miss and to access the system I/O resources

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  • Help identify the pattern for reacting on updates

    - by Mike
    There's an entity that gets updated from external sources. Update events are at random intervals. And the entity has to be processed once updated. Multiple updates may be multiplexed. In other words there's a need for the most current state of entity to be processed. There's a point of no-return during processing where the current state (and the state is consistent i.e. no partial update is made) of entity is saved somewhere else and processing goes on independently of any arriving updates. Every consequent set of updates has to trigger processing i.e. system should not forget about updates. And for each entity there should be no more than one running processing (before the point of no-return) i.e. the entity state should not be processed more than once. So what I'm looking for is a pattern to cancel current processing before the point of no return or abandon processing results if an update arrives. The main challenge is to minimize race conditions and maintain integrity. The entity sits mainly in database with some files on disk. And the system is in .NET with web-services and message queues. What comes to my mind is a database queue-like table. An arriving update inserts row in that table and the processing is launched. The processing gathers necessary data before the point of no-return and once it reaches this barrier it looks into the queue table and checks whether there're more recent updates for the entity. If there are new updates the processing simply shuts down and its data is discarded. Otherwise the processing data is persisted and it goes beyond the point of no-return. Though it looks like a solution to me it is not quite elegant and I believe this scenario may be supported by some sort of middleware. If I would use message queues for this then there's a need to access the queue API in the point of no-return to check for the existence of new messages. And this approach also lacks elegance. Is there a name for this pattern and an existing solution?

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  • Windows Server 2008 Software Raid 5 - Data integrity issues

    - by Fopedush
    I've got a server running Windows Server 2008 R2, with a (windows native) software raid-5 array. The array consists of 7x 1TB Western Digital RE3 and RE4 drives. I have offline backups of this array. The problem is this: I noticed a few days ago after copying a large file to the disk that there was an integrity issue with that file - it was a ~12GB file that I had downloaded via uTorrent. After moving it to the raid array, I used uTorrent to relocate the download location, and performed a re-check so I could seed it from that location. The recheck found that only 6308/6310 chunks of the copied file were intact. My next step was to write a quick powershell script that would copy files to the array, while performing a SHA1 hash of the original and resultant files and comparing them. Smaller files (100-1000MB) copied over just fine. When I started copying larger data (~15GB), I found that the hash check failed about 2/3rds of the time. The corrupt files had very, very small inconsistencies - less than .01%. I further eliminated the possibility of networking or client issues by placing this large file on the C:\ of the server, and copying it repeatedly from there to the array, seeing similar results. Copying the data via explorer, powershell, or the standard windows command prompt yield the same results. None of the copies fail or report any problems. The raid array itself is listed as healthy in disk management. After a few experiments, I shut down the server and ran memtest overnight. No errors were detected. A basic run of chkdsk found no problems, but I did not use the /R flag, as I was unsure how that might affect a software raid-5 volume. I next ran Crystal Disk Info to check the smart data on the drives - but found that CDI only detected 5 out of 7 of the disks in the array. I have no idea why. Nevertheless, CDI shows the following "caution" flags on a single one of the drives: 05 199 199 140 000000000001 Reallocated Sectors Count C5 200 200 __0 000000000001 Current Pending Sector Count Which is a little bit alarming, but I don't really know what to do with the information. I hardly feel like one reallocated sector could be causing this. At this point, I'm looking for some guidance on what to do next. I need to determine the cause of this issue, but I'm hesitant to run chkdsk /R or any bootable disk health checkers because I'm afraid they might break the array. I've considered triggering a re-sync of the array, but I'm not actually sure how to do that without doing something silly like manually dropping a disk and then restoring it. Any advice that could help me ferret out the precise cause of this issue would be greatly appreciated.

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  • Dual booting windows 8/ubuntu 12.04.2, Grub doesn't appear and machine never boot in ubuntu

    - by black sensei
    i got a new ACER predator AG3620-UR308 which came with windows 8, so i wanted to run ubuntu 12.04.2 on it as a dual booting. To be honest, i've been doing dual booting for a while now so, i did the right thing. the box came with 2TB HDD. so i made 4 partitions with a raw partition just after the windows installation partition I always do manual installation so even if ubuntu didn't detect windows 8, it was ok for me. So i created swap area and finished the installation etc....Grub was install on the only drive there which is sda. After reboot, grub doesn't even come up.So it always boot in windows 8. I did repeat the installation process twice and yield same result. which is weird because this method always works for me so far.Even the laptop am using to write this post is a dual booting windows 7/ mint nadia installed the same way. Is there anything new in windows 8 that i didn't make provision for? Before starting the installation, all i read about was that , windows 8 should be installed first and ubuntu after. I went ahead and disable secure boot from the BIOS and enabled CSM (don't even know what it means) according to Acer custhelp site . I boot from USB and did fdisk -l bellow is the result: ubuntu@ubuntu:~$ sudo fdisk -l WARNING: GPT (GUID Partition Table) detected on '/dev/sda'! The util fdisk doesn't support GPT. Use GNU Parted. Disk /dev/sda: 2000.4 GB, 2000398934016 bytes 255 heads, 63 sectors/track, 243201 cylinders, total 3907029168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0x8c361cb5 Device Boot Start End Blocks Id System /dev/sda1 1 3907029167 1953514583+ ee GPT Partition 1 does not start on physical sector boundary. Disk /dev/sdb: 8178 MB, 8178892800 bytes 255 heads, 63 sectors/track, 994 cylinders, total 15974400 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x0006a87e Device Boot Start End Blocks Id System /dev/sdb1 * 2048 15972351 7985152 b W95 FAT32 ubuntu@ubuntu:~$ Can anybody shed some light? thank you in advance EDIT Hey, i just did another trial with 13.04 this time and still no luck. bios: secure-boot: disabled enable CSM : always 1-delete previous ubuntu partition and swap area partition.now having free space 2- used usb installer to prepare usb with ubuntu-13.04-desktop-amd64.iso 3- rebooted : liveusb didnt detect windows 8, used something else 4-created partition ext4 for / 5-created partition for swap-area 6- default grub path is /dev/sda and clicked install Acer always boots into windows.

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  • SQL Monitor Performance Metric: Buffer Cache Used Per Database in MB

    Data pages read from disk are placed in the buffer pool with the intention that they will be reused, and accessing them from RAM is faster than from disk. Knowing how much of your RAM is committed to each database can help you provision the right amount of RAM to SQL Server, and also to identify rogue queries that draw too much data into RAM and force data from other databases out of the cache. Deployment Manager 2 is now free!The new version includes tons of new features and we've launched a completely free Starter Edition! Get Deployment Manager here

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  • Dual booting windows 8/ubuntu 12.04. Grub doesn't appear and machine never boot in ubuntu

    - by black sensei
    i got a new ACER predator AG3620-UR308 which came with windows 8, so i wanted to run ubuntu 12.04.2 on it as a dual booting. To be honest, i've been doing dual booting for a while now so, i did the right thing. the box came with 2TB HDD. so i made 4 partitions with a raw partition just after the windows installation partition I always do manual installation so even if ubuntu didn't detect windows 8, it was ok for me. So i created swap area and finished the installation etc....Grub was install on the only drive there which is sda. After reboot, grub doesn't even come up.So it always boot in windows 8. I did repeat the installation process twice and yield same result. which is weird because this method always works for me so far.Even the laptop am using to write this post is a dual booting windows 7/ mint nadia installed the same way. Is there anything new in windows 8 that i didn't make provision for? Before starting the installation, all i read about was that , windows 8 should be installed first and ubuntu after. I went ahead and disable secure boot from the BIOS and enabled CSM (don't even know what it means) according to Acer custhelp site . I boot from USB and did fdisk -l bellow is the result: ubuntu@ubuntu:~$ sudo fdisk -l WARNING: GPT (GUID Partition Table) detected on '/dev/sda'! The util fdisk doesn't support GPT. Use GNU Parted. Disk /dev/sda: 2000.4 GB, 2000398934016 bytes 255 heads, 63 sectors/track, 243201 cylinders, total 3907029168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0x8c361cb5 Device Boot Start End Blocks Id System /dev/sda1 1 3907029167 1953514583+ ee GPT Partition 1 does not start on physical sector boundary. Disk /dev/sdb: 8178 MB, 8178892800 bytes 255 heads, 63 sectors/track, 994 cylinders, total 15974400 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x0006a87e Device Boot Start End Blocks Id System /dev/sdb1 * 2048 15972351 7985152 b W95 FAT32 ubuntu@ubuntu:~$ Can anybody shed some light? thank you in advance

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  • Multicasting and VMWare

    - by John Breakwell
    Cracked a Multicasting problem this evening for one of my Canadian Tweeple. They wanted to mulitcast some MSMQ messages to another machine but nothing was arriving in the listening queue. A local queue could be configured to listen to the particular IP address/port in use and messages would arrive, though. Looking at the network traffic, nothing was going onto the wire for the IP address/port pair until they looked at traffic to the VMWare adapter. The machine had a virtual machine to simulate a remote computer and when they changed the setup from NAT to Bridge, multicasting burst into life.

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  • Why my collision detection is not accurate?

    - by optimisez
    After trying and trying, I still cannot understand why the leg of character exceeds the wall but no clipping issue when I hit the wall from below. How should I fix it to make him standstill on the wall? void initPlayer() { // Create texture. hr = D3DXCreateTextureFromFileEx(d3dDevice, "player.png", 169, 44, D3DX_DEFAULT, NULL, D3DFMT_A8R8G8B8, D3DPOOL_MANAGED, D3DX_DEFAULT, D3DX_DEFAULT, D3DCOLOR_XRGB(255, 255, 255), NULL, NULL, &player); playerRect.left = playerRect.top = 0; playerRect.right = 29; playerRect.bottom = 36; playerDest.X = 0; playerDest.Y = 564; playerDest.length = playerRect.right - playerRect.left; playerDest.height = playerRect.bottom - playerRect.top; } void initBox() { hr = D3DXCreateTextureFromFileEx(d3dDevice, "brock.png", 330, 132, D3DX_DEFAULT, NULL, D3DFMT_A8R8G8B8, D3DPOOL_MANAGED, D3DX_DEFAULT, D3DX_DEFAULT, D3DCOLOR_XRGB(255, 255, 255), NULL, NULL, &box); boxRect.left = 33; boxRect.top = 0; boxRect.right = 63; boxRect.bottom = 30; boxDest.X = boxDest.Y = 300; boxDest.length = boxRect.right - boxRect.left; boxDest.height = boxRect.bottom - boxRect.top; } bool spriteCollide(Entity player, Entity target) { float left1, left2; float right1, right2; float top1, top2; float bottom1, bottom2; left1 = player.X; left2 = target.X; right1 = player.X + player.length; right2 = target.X + target.length; top1 = player.Y; top2 = target.Y; bottom1 = player.Y + player.height; bottom2 = target.Y + target.height; if (bottom1 < top2) return false; if (top1 > bottom2) return false; if (right1 < left2) return false; if (left1 > right2) return false; return true; } void collideWithBox() { if ( spriteCollide(playerDest, boxDest) && keyArr[VK_UP]) //playerDest.Y += 50; playerDest.Y = boxDest.Y + boxDest.height; else if ( spriteCollide(playerDest, boxDest) && !keyArr[VK_UP]) playerDest.Y = boxDest.Y - boxDest.height; }

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  • Multiplayer tile based movement synchronization

    - by Mars
    I have to synchronize the movement of multiple players over the Internet, and I'm trying to figure out the safest way to do that. The game is tile based, you can only move in 4 directions, and every move moves the sprite 32px (over time of course). Now, if I would simply send this move action to the server, which would broadcast it to all players, while the walk key is kept being pressed down, to keep walking, I have to take this next command, send it to the server, and to all clients, in time, or the movement won't be smooth anymore. I saw this in other games, and it can get ugly pretty quick, even without lag. So I'm wondering if this is even a viable option. This seems like a very good method for single player though, since it's easy, straight forward (, just take the next movement action in time and add it to a list), and you can easily add mouse movement (clicking on some tile), to add a path to a queue, that's walked along. The other thing that came to my mind was sending the information that someone started moving in some direction, and again once he stopped or changed the direction, together with the position, so that the sprite will appear at the correct position, or rather so that the position can be fixed if it's wrong. This should (hopefully) only make problems if someone really is lagging, in which case it's to be expected. For this to work out I'd need some kind of queue though, where incoming direction changes and stuff are saved, so the sprite knows where to go, after the current movement to the next tile is finished. This could actually work, but kinda sounds overcomplicated. Although it might be the only way to do this, without risk of stuttering. If a stop or direction change is received on the client side it's saved in a queue and the char keeps moving to the specified coordinates, before stopping or changing direction. If the new command comes in too late there'll be stuttering as well of course... I'm having a hard time deciding for a method, and I couldn't really find any examples for this yet. My main problem is keeping the tile movement smooth, which is why other topics regarding synchronization of pixel based movement aren't helping too much. What is the "standard" way to do this?

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  • I was stuck in implementing Simple Ftp with Winsock [migrated]

    - by user67449
    I want to implement a SimpleFtp with Winsock. But I was stuck in the maybe the file stream reading and writing. This is the Server. #include <WinSock2.h> #include <memory.h> #include <stdio.h> #include <iostream> using namespace std; #pragma comment(lib, "ws2_32.lib") #define MAX_FILE_NAME 100 #define DATA_PACK_SIZE 80*1000 // ??DataPack?????80KB #define SOCKKET_BUFFER_SIZE 80*1000 // socket??? #define FILE_BUFFER_SIZE DATA_PACK_SIZE-MAX_FILE_NAME-4*sizeof(int)-sizeof(u_long) //?????,??,??????content????? #define CONTENT_SIZE FILE_BUFFER_SIZE // DataPack?????content??? // Define a structure to hold the content of a file typedef struct FilePack{ char fName[MAX_FILE_NAME]; // File's name int fLen; // File's length int packNum; // Number of the DataPack int packLen; // DataPack's length int packCount; int contenLen; // the content length the DataPack actually holds u_long index; // ?????????? char content[CONTENT_SIZE]; // DataPack?????? }DataPack, *pDataPack; void WinsockInitial(){ WSADATA wsaData; WORD wVersionRequested; int err; wVersionRequested=MAKEWORD(2,2); err=WSAStartup(wVersionRequested, &wsaData); if(err!=0){ cout<<"Error at WSAStartup()."<<endl; exit(0); } if( LOBYTE(wsaData.wVersion)!=2 || HIBYTE(wsaData.wVersion)!=2 ){ cout<<"Error at version of Winsock. "<<endl; WSACleanup(); exit(0); } } void SockBind(SOCKET sock, int port, sockaddr_in &addrsock){ addrsock.sin_family=AF_INET; addrsock.sin_port=htons(port); addrsock.sin_addr.S_un.S_addr=htonl(INADDR_ANY); if( bind(sock, (sockaddr*)&addrsock, sizeof(addrsock)) == SOCKET_ERROR ){ cout<<"Error at bind(). Error: "<<GetLastError()<<endl; closesocket(sock); WSACleanup(); exit(0); } } void SockListen(SOCKET sock, int bak){ int err=listen(sock, bak); if(err==SOCKET_ERROR){ cout<<"Error at listen()."<<WSAGetLastError()<<endl; closesocket(sock); WSACleanup(); exit(0); } } int SockSend(DataPack &dataPack, SOCKET sock, char *sockBuf){ int bytesLeft=0, bytesSend=0; int idx=0; bytesLeft=sizeof(dataPack); // ?DataPack?????sockBuf??? memcpy(sockBuf, &dataPack, sizeof(dataPack)); while(bytesLeft>0){ bytesSend=send(sock, &sockBuf[idx], bytesLeft, 0); if(bytesSend==SOCKET_ERROR){ cout<<"Error at send()."<<endl; return 1; } bytesLeft-=bytesSend; idx+=bytesSend; } return 0; } int GetFileLen(FILE *fp){ // ?????? if(fp==NULL){ cout<<"Invalid argument. Error at GetFileLen()."<<endl; exit(0); } fseek(fp, 0, SEEK_END); int tempFileLen=ftell(fp); fseek(fp, 0, SEEK_SET); return tempFileLen; } int main(){ int err; sockaddr_in addrServ; int port=8000; // Initialize Winsock WinsockInitial(); // Create a socket SOCKET sockListen=socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); if(sockListen==INVALID_SOCKET){ cout<<"Error at socket()."<<endl; WSACleanup(); return 1; } // Bind the socket. SockBind(sockListen, port, addrServ); // Listen for incoming connection requests cout<<"Waiting for incoming connection requests..."<<endl; SockListen(sockListen, 5); // Accept the connection request. sockaddr_in addrClient; int len=sizeof(addrClient); SOCKET sockConn=accept(sockListen, (sockaddr*)&addrClient, &len); if(sockConn!=INVALID_SOCKET){ cout<<"Connected to client successfully."<<endl; } // Set the buffer size of socket char sockBuf[SOCKKET_BUFFER_SIZE]; int nBuf=SOCKKET_BUFFER_SIZE; int nBufLen=sizeof(nBuf); err=setsockopt(sockConn, SOL_SOCKET, SO_SNDBUF, (char*)&nBuf, nBufLen); if(err!=0){ cout<<"Error at setsockopt(). Failed to set buffer size for socket."<<endl; exit(0); } //??????????? err = getsockopt(sockConn, SOL_SOCKET, SO_SNDBUF, (char*)&nBuf, &nBufLen); if( SOCKKET_BUFFER_SIZE != nBuf){ cout<<"Error at setsockopt(). ?socket????????"<<endl; closesocket(sockListen); closesocket(sockConn); WSACleanup(); exit(0); } //------------------------------------------------------------------------// DataPack dataPackSend; memset(&dataPackSend, 0, sizeof(dataPackSend)); int bytesRead; int bytesLeft; int bytesSend; int packCount; // Counts how many DataPack needed FILE *frp; // Used to read if(strcpy_s(dataPackSend.fName, "music.mp3")!=0){ cout<<"Error at strcpy_s()."<<endl; return 1; } // Open the file in read+binary mode err=fopen_s(&frp, dataPackSend.fName, "rb"); if(err!=0){ cout<<"Error at fopen_s()."<<endl; return 1; } char fileBuf[FILE_BUFFER_SIZE]; // Set the buffer size of File if(setvbuf(frp, fileBuf, _IONBF, FILE_BUFFER_SIZE)!=0){ cout<<"Error at setvbuf().Failed to set buffer size for file."<<endl; closesocket(sockListen); closesocket(sockConn); WSACleanup(); exit(0); } // Get file's length int fileLen=GetFileLen(frp); cout<<"File ???:"<<fileLen<<" bytes."<<endl; // Calculate how many DataPacks needed packCount=ceil( (double)fileLen/CONTENT_SIZE ); cout<<"File Length: "<<fileLen<<" "<<"Content Size: "<<CONTENT_SIZE<<endl; cout<<"???"<<packCount<<" ?DataPack"<<endl; int i=0; for(i=0; i<packCount; i++){ //?????dataPackSend????? memset(&dataPackSend, 0, sizeof(dataPackSend)); // Fill the dataPackSend if(strcpy_s(dataPackSend.fName, "abc.txt")!=0){ cout<<"Error at strcpy_s()."<<endl; return 1; } dataPackSend.packLen=DATA_PACK_SIZE; dataPackSend.fLen=fileLen; dataPackSend.packCount=packCount; if( packCount==1 ){ //??DataPack??? bytesRead=fread(fileBuf, 1, dataPackSend.fLen, frp); dataPackSend.contenLen=dataPackSend.fLen; memcpy(dataPackSend.content, fileBuf, bytesRead); dataPackSend.packNum=0; //???????DataPack // ?????dataPackSend?Client? if( SockSend(dataPackSend, sockConn, sockBuf)==0 ){ cout<<"??? "<<dataPackSend.packNum<<" ?DataPack"<<endl; } }else if( packCount>1 && i<(packCount-1) ){ // ???(???????) bytesRead=fread(fileBuf, 1, CONTENT_SIZE, frp); dataPackSend.contenLen=CONTENT_SIZE; memcpy(dataPackSend.content, fileBuf, bytesRead); dataPackSend.packNum=i; //?dataPackSend??????Client? if( SockSend(dataPackSend, sockConn, sockBuf)==0 ){ cout<<"??? "<<dataPackSend.packNum<<" ?DataPack."<<endl; } }else{ // ????? bytesRead=fread(fileBuf, 1, (dataPackSend.fLen-i*CONTENT_SIZE), frp); dataPackSend.contenLen=dataPackSend.fLen-i*CONTENT_SIZE; memcpy(dataPackSend.content, fileBuf, bytesRead); dataPackSend.packNum=i; //?dataPackSend???Client? if( SockSend(dataPackSend, sockConn, sockBuf)==0 ){ cout<<"??? "<<dataPackSend.packNum<<" ?DataPack."<<endl; } } } fclose(frp); closesocket(sockListen); closesocket(sockConn); WSACleanup(); return 0; } And this is Client. #include <WinSock2.h> #include <memory.h> #include <stdio.h> #include <iostream> using namespace std; #pragma comment(lib, "ws2_32.lib") #define MAX_FILE_NAME 100 #define DATA_PACK_SIZE 80*1000 // ??DataPack?????80KB #define SOCKKET_BUFFER_SIZE 80*1000 // socket??? #define FILE_BUFFER_SIZE DATA_PACK_SIZE-MAX_FILE_NAME-4*sizeof(int)-sizeof(u_long) //?????,??,??????content????? #define CONTENT_SIZE FILE_BUFFER_SIZE // DataPack?????content??? // Define a structure to hold the content of a file typedef struct FilePack{ char fName[MAX_FILE_NAME]; // File's name int fLen; // File's length int packNum; // Number of the DataPack int packLen; // DataPack's length int packCount; //DataPack??? int contenLen; // the content length the DataPack actually holds u_long index; // ?????????? char content[CONTENT_SIZE]; // DataPack?????? }DataPack, *pDataPack; void WinsockInitial(){ WSADATA wsaData; WORD wVersionRequested; int err; wVersionRequested=MAKEWORD(2,2); err=WSAStartup(wVersionRequested, &wsaData); if(err!=0){ cout<<"Error at WSAStartup()."<<endl; exit(0); } if( LOBYTE(wsaData.wVersion)!=2 || HIBYTE(wsaData.wVersion)!=2 ){ cout<<"Error at version of Winsock. "<<endl; WSACleanup(); exit(0); } } int SockRecv(SOCKET sock, char *sockBuf){ int bytesLeft, bytesRecv; int idx=0; bytesLeft=DATA_PACK_SIZE; while(bytesLeft>0){ bytesRecv=recv(sock, &sockBuf[idx], bytesLeft, 0); if(bytesRecv==SOCKET_ERROR){ cout<<"Error at recv()."<<endl; return 1; } bytesLeft-=bytesRecv; idx+=bytesRecv; } return 0; } int main(){ int err; sockaddr_in addrServ; int port=8000; // Initialize Winsock WinsockInitial(); // Create a socket SOCKET sockClient=socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); if(sockClient==INVALID_SOCKET){ cout<<"Error at socket()."<<endl; WSACleanup(); return 1; } // Set the buffer size of socket char sockBuf[SOCKKET_BUFFER_SIZE]; int nBuf=SOCKKET_BUFFER_SIZE; int nBufLen=sizeof(nBuf); err=setsockopt(sockClient, SOL_SOCKET, SO_RCVBUF, (char*)&nBuf, nBufLen); if(err!=0){ cout<<"Error at setsockopt(). Failed to set buffer size for socket."<<endl; exit(0); } //??????????? err = getsockopt(sockClient, SOL_SOCKET, SO_RCVBUF, (char*)&nBuf, &nBufLen); if( SOCKKET_BUFFER_SIZE != nBuf){ cout<<"Error at getsockopt(). ?socket????????"<<endl; closesocket(sockClient); WSACleanup(); exit(0); } // Connect to the Server addrServ.sin_family=AF_INET; addrServ.sin_port=htons(port); addrServ.sin_addr.S_un.S_addr=inet_addr("127.0.0.1"); err=connect(sockClient, (sockaddr*)&addrServ, sizeof(sockaddr)); if(err==SOCKET_ERROR){ cout<<"Error at connect()."<<GetLastError()<<endl; closesocket(sockClient); WSACleanup(); return 1; }else{ cout<<"Connected to the FTP Server successfully."<<endl; } /* int i=0; int bytesRecv, bytesLeft, bytesWrite; int packCount=0, fLen=0; DataPack dataPackRecv; //?????? SockRecv(sockClient, sockBuf); memcpy(&dataPackRecv, sockBuf, sizeof(dataPackRecv)); cout<<"???? "<<dataPackRecv.packNum<<" ?DataPack."<<endl; cout<<"?DataPack??fName????: "<<dataPackRecv.fName<<endl; //??????? packCount=dataPackRecv.packCount; cout<<"?? "<<packCount<<" ?DataPack."<<endl; fLen=dataPackRecv.fLen; // Create a local file to write into FILE *fwp; err=fopen_s(&fwp, dataPackRecv.fName, "wb"); if(err!=0){ cout<<"Error at creat fopen_s(). Failed to create a local file to write into."<<endl; return 1; } // Set the buffer size of File char fileBuf[FILE_BUFFER_SIZE]; if(setvbuf(fwp, fileBuf, _IONBF, FILE_BUFFER_SIZE)!=0){ cout<<"Error at setvbuf().Failed to set buffer size for file."<<endl; memset(fileBuf, 0, sizeof(fileBuf)); closesocket(sockClient); WSACleanup(); exit(0); } //???????content???? memcpy(fileBuf, dataPackRecv.content, sizeof(dataPackRecv.content)); bytesWrite=fwrite(fileBuf, 1, sizeof(fileBuf), fwp); if(bytesWrite<sizeof(fileBuf)){ cout<<"Error at fwrite(). Failed to write the content of dataPackRecv to local file."<<endl; } //?????packCount-1????????????????? for(int i=1; i<packCount; i++){ // ????????? memset(sockBuf, 0, sizeof(sockBuf)); memset(&dataPackRecv, 0, sizeof(dataPackRecv)); memset(fileBuf, 0, sizeof(fileBuf)); SockRecv(sockClient, sockBuf); memcpy(&dataPackRecv, sockBuf, sizeof(dataPackRecv)); cout<<"???? "<<dataPackRecv.packNum<<" ?DataPack."<<endl; //???? memcpy(fileBuf, dataPackRecv.content, dataPackRecv.contenLen); bytesWrite=fwrite(fileBuf, 1, dataPackRecv.contenLen, fwp); if(bytesWrite<dataPackRecv.contenLen){ cout<<"Error at fwrite(). Failed to write the content of dataPackRecv to local file."<<endl; } } if( (i+1)==packCount ){ cout<<"??DataPack????????!"<<endl; } fclose(fwp); closesocket(sockClient); WSACleanup(); return 0;*/ }

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  • Echo 404 directly from nginx to improve performance

    - by user64204
    I am in charge of production servers serving static content for a website. Those servers are constantly being crawled by bots looking for potential exploits (which isn't that much of a problem security-wise because no application can be reached behind the web server) but generates thousands of 404 per day, sometimes per hour. I am looking into ways of blocking those requests but it's tricky (you want to make sure you don't block legitimate traffic and these bots are becoming more and more clever at looking like they're legit) and is going to take me a while to find an acceptable solution. In the meantime I would like to reduce the performance impact of serving those 404 pages. Indeed we're using nginx which by default is configured to serve it's 404 page from the disk (This can be changed using the error_page directive but in the end the 404 will either have to be served from disk or from another external source (e.g. upstream application which would be worst)) which isn't ideal. I ran a test with ab on my local machine with a basic configuration: in one case I echo a message directly from nginx so the disk isn't touched at all, in the other case I hit a missing page and nginx serves its 404 from disk. server { # [...] the default nginx stuff location / { } location /this_page_exists { echo "this page was found"; } } Here are the test results (my laptop has Intel(R) Core(TM) i7-2670QM + SSD in case you're wondering why they are so high): $ ab -n 500000 -c 1000 http://localhost/this_page_exists Requests per second: 25609.16 [#/sec] (mean) $ ab -n 500000 -c 1000 http://localhost/this_page_doesnt_exists Requests per second: 22905.72 [#/sec] (mean) As you can see, returning a value with echo is 11% ((25609-22905)÷22905×100) faster than serving the 404 page from disk. Accordingly I would like to echo a simple 404 Page not Found string from nginx. I tried many things so far but they all failed, essentially the idea was this: location / { try_files $uri @not_found; } location @not_found { echo "404 - Page not found"; } The problem is that as soon as the echo directive is used, the http response code is set to 200. I tried changing that by doing error_page 200 = 400 but that breaks the configuration. How can I serve a 404 page directly from nginx? (without hacking the source which may be might next step)

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  • Ubuntu 12.10 Live USB BootError

    - by Sivan
    I am a Linux Newbee, running ubuntu 12.04 i386 on a 64-bit machine. Now I just downloaded Ubuntu 12.10 AMD64 iso and made a bootable USB using Startup Disk Creator. I was directed to install available updated packages, which I did install. The Startup Disk was succesfully created. But when I tried to boot from the USB I am getting a BootError message and nothing else. What could have gone wrong?

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  • How can I do fast Triangle/Square vs Triangle collision detection?

    - by Ólafur Waage
    I have a game world where the objects are in a grid based environment with the following restrictions. All of the triangles are 45-90-45 triangles that are unit length. They can only rotate 90°. The squares are of unit length and can not rotate (not that it matters) I have the Square vs Square detection down and it is very very solid and very fast (max vs min on x and y values) Wondering if there are any tricks I can employ since I have these restrictions on the triangles?

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  • Getting windows 7 to boot from external hard drive. Using Ubuntu

    - by SMS
    I have Ubuntu 12.04LTS as my current operating system, and I have a Windows 7 iso on a disk. I'm using an external hard drive because my internal hard drive has become damaged. I need to get Windows to install onto my external hard drive (where Ubuntu is as well). The iso disk will not install windows to the hard drive. Can anyone help guide me through the process of getting windows on the external?

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  • USB hard drive not recognized

    - by user318772
    Until recently I was using the portable USB hard drive in my win 7 laptop and ubuntu laptop. Suddenly now none of the laptops recognize it. This is the message i get by doing lsusb... Bus 001 Device 004: ID 1058:1010 Western Digital Technologies, Inc. Elements External HDD Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 003 Device 003: ID 0b97:7762 O2 Micro, Inc. Oz776 SmartCard Reader Bus 003 Device 002: ID 0b97:7761 O2 Micro, Inc. Oz776 1.1 Hub Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 002 Device 002: ID 413c:a005 Dell Computer Corp. Internal 2.0 Hub Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub fdisk doesn't show the external hard drive Disk /dev/sda: 80.0 GB, 80026361856 bytes 255 heads, 63 sectors/track, 9729 cylinders, total 156301488 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x0004a743 Device Boot Start End Blocks Id System /dev/sda1 * 2048 152111103 76054528 83 Linux /dev/sda2 152113150 156301311 2094081 5 Extended /dev/sda5 152113152 156301311 2094080 82 Linux swap / Solaris when i do testdisk TestDisk 6.14, Data Recovery Utility, July 2013 Christophe GRENIER <[email protected]> http://www.cgsecurity.org TestDisk is free software, and comes with ABSOLUTELY NO WARRANTY. Select a media (use Arrow keys, then press Enter): >Disk /dev/sda - 80 GB / 74 GiB - ST980825AS Disk /dev/sdb - 2199 GB / 2048 GiB testdisk-> Intel->analyse I get partition error Disk /dev/sdb - 2199 GB / 2048 GiB - CHS 2097152 64 32 Current partition structure: Partition Start End Size in sectors Partition: Read error Here is the output of dmesg [11948.549171] Add. Sense: Invalid command operation code [11948.549177] sd 2:0:0:0: [sdb] CDB: [11948.549181] Read(16): 88 00 00 00 00 00 00 00 00 00 00 00 00 08 00 00 [11948.550489] sd 2:0:0:0: [sdb] Invalid command failure [11948.550495] sd 2:0:0:0: [sdb] [11948.550499] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE [11948.550505] sd 2:0:0:0: [sdb] [11948.550508] Sense Key : Illegal Request [current] [11948.550514] Info fld=0x0 [11948.550519] sd 2:0:0:0: [sdb] [11948.550525] Add. Sense: Invalid command operation code [11948.550531] sd 2:0:0:0: [sdb] CDB: [11948.550534] Read(16): 88 00 00 00 00 00 00 00 00 00 00 00 00 08 00 00 [11948.551870] sd 2:0:0:0: [sdb] Invalid command failure [11948.551876] sd 2:0:0:0: [sdb] [11948.551880] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE [11948.551885] sd 2:0:0:0: [sdb] [11948.551888] Sense Key : Illegal Request [current] [11948.551895] Info fld=0x0 [11948.551900] sd 2:0:0:0: [sdb] [11948.551905] Add. Sense: Invalid command operation code [11948.551911] sd 2:0:0:0: [sdb] CDB: [11948.551914] Read(16): 88 00 00 00 00 00 00 00 00 00 00 00 00 08 00 00 If possible i want to retrive at least some data from this hard drive. If thats not possible I would like to format it and use it. Any help will be greatly appreciated Thanks

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  • Using a PowerShell Script to delete old files for SQL Server

    Many clients are using custom stored procedures or third party tools to backup databases in production environments instead of using database maintenance plans. One of the things that you need to do is to maintain the number of backup files that exist on disk, so you don't run out of disk space. There are several techniques for deleting old files, but in this tip I show how this can be done using PowerShell.

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  • Why is my collision detection not accurate?

    - by optimisez
    After trying and trying, I still cannot understand why the leg of character exceeds the wall but no clipping issue when I hit the wall from below. How should I fix it to make him stand still on the wall? From collideWithBox() function below, it shows that playerDest.Y = boxDest.Y - boxDest.height; will get the position the character should standstill on the wall. Theoretically, the clipping effect won't be happen as the character hit the box from below works with the equation playerDest.Y = boxDest.Y + boxDest.height;. void collideWithBox() { if ( spriteCollide(playerDest, boxDest) && keyArr[VK_UP]) //playerDest.Y += 50; playerDest.Y = boxDest.Y + boxDest.height; else if ( spriteCollide(playerDest, boxDest) && !keyArr[VK_UP]) playerDest.Y = boxDest.Y - boxDest.height; } void initPlayer() { // Create texture. hr = D3DXCreateTextureFromFileEx(d3dDevice, "player.png", 169, 44, D3DX_DEFAULT, NULL, D3DFMT_A8R8G8B8, D3DPOOL_MANAGED, D3DX_DEFAULT, D3DX_DEFAULT, D3DCOLOR_XRGB(255, 255, 255), NULL, NULL, &player); playerRect.left = playerRect.top = 0; playerRect.right = 29; playerRect.bottom = 36; playerDest.X = 0; playerDest.Y = 564; playerDest.length = playerRect.right - playerRect.left; playerDest.height = playerRect.bottom - playerRect.top; } void initBox() { hr = D3DXCreateTextureFromFileEx(d3dDevice, "brock.png", 330, 132, D3DX_DEFAULT, NULL, D3DFMT_A8R8G8B8, D3DPOOL_MANAGED, D3DX_DEFAULT, D3DX_DEFAULT, D3DCOLOR_XRGB(255, 255, 255), NULL, NULL, &box); boxRect.left = 33; boxRect.top = 0; boxRect.right = 63; boxRect.bottom = 30; boxDest.X = boxDest.Y = 300; boxDest.length = boxRect.right - boxRect.left; boxDest.height = boxRect.bottom - boxRect.top; } bool spriteCollide(Entity player, Entity target) { float left1, left2; float right1, right2; float top1, top2; float bottom1, bottom2; left1 = player.X; left2 = target.X; right1 = player.X + player.length; right2 = target.X + target.length; top1 = player.Y; top2 = target.Y; bottom1 = player.Y + player.height; bottom2 = target.Y + target.height; if (bottom1 < top2) return false; if (top1 > bottom2) return false; if (right1 < left2) return false; if (left1 > right2) return false; return true; }

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  • JGridView

    - by Geertjan
    JGrid was announced last week so I wanted to integrate it into a NetBeans Platform app. I.e., I'd like to use Nodes instead of the DefaultListModel that is supported natively, so that I can integrate with the Properties Window, for example: Here's how: import de.jgrid.JGrid; import java.beans.PropertyVetoException; import javax.swing.DefaultListModel; import javax.swing.JScrollPane; import javax.swing.event.ListSelectionEvent; import javax.swing.event.ListSelectionListener; import org.book.domain.Book; import org.openide.explorer.ExplorerManager; import org.openide.nodes.Node; import org.openide.util.Exceptions; public class JGridView extends JScrollPane { @Override public void addNotify() { super.addNotify(); final ExplorerManager em = ExplorerManager.find(this); if (em != null) { final JGrid grid = new JGrid(); Node root = em.getRootContext(); final Node[] nodes = root.getChildren().getNodes(); final Book[] books = new Book[nodes.length]; for (int i = 0; i < nodes.length; i++) { Node node = nodes[i]; books[i] = node.getLookup().lookup(Book.class); } grid.getCellRendererManager().setDefaultRenderer(new OpenLibraryGridRenderer()); grid.setModel(new DefaultListModel() { @Override public int getSize() { return books.length; } @Override public Object getElementAt(int i) { return books[i]; } }); grid.setUI(new BookshelfUI()); grid.getSelectionModel().addListSelectionListener(new ListSelectionListener() { @Override public void valueChanged(ListSelectionEvent e) { //Somehow compare the selected item //with the list of books and find a matching book: int selectedIndex = grid.getSelectedIndex(); for (int i = 0; i < nodes.length; i++) { String nodeName = books[i].getTitel(); if (String.valueOf(selectedIndex).equals(nodeName)) { try { em.setSelectedNodes(new Node[]{nodes[i]}); } catch (PropertyVetoException ex) { Exceptions.printStackTrace(ex); } } } } }); setViewportView(grid); } } } Above, you see references to OpenLibraryGridRenderer and BookshelfUI, both of which are part of the "JGrid-Bookshelf" sample in the JGrid download. The above is specific for Book objects, i.e., that's one of the samples that comes with the JGrid download. I need to make the above more general, so that any kind of object can be handled without requiring changes to the JGridView. Once you have the above, it's easy to integrate it into a TopComponent, just like any other NetBeans explorer view.

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  • Normal Redundancy (Double Mirroring) Option Available

    - by TammyBednar
    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:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif";} The Oracle Database Appliance 2.4 Patch was released last week and provides you an option of ASM normal redundancy (double mirroring) during the initial deployment of the Database Appliance. The default deployment of the Oracle Database Appliance is high redundancy for the +DATA and +RECO disk groups. While there is 12TB of raw shared storage available, the Database Backup Location and Disk Group Redundancy govern how much usable storage is presented after the initial deployment is completed. The Database Backup Location options are Local or External. When the Local Backup Option is selected, this means that 60% of the available shared storage will be allocated for the Fast Recovery Area that contains database backups and archive logs. The External Backup Option will allocate 20% of the available shared storage to the Fast Recovery Area. So, let’s look at an example of High Redundancy and External Backups. Disk Group Redundancy – High --> Triple Mirroring to provide ~4TB of available storage Database Backup Location – External --> 20% of available shared storage allocated to +RECO +DATA = 3.2TB of usable storage, +RECO = 0.8TB of usable storage What about Normal Redundancy with External Backups? Disk Group Redundancy – Normal --> Double Mirroring to provide ~6TB of available storage Database Backup Location – External --> 20% of available shared storage allocated to +RECO +DATA = 4.8TB of usable storage, +RECO = 1.2TB of usable storage As a best practice, we would recommend using Normal Redundancy for your test and/or development Oracle Database Appliances and High Redundancy for production.

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  • Subdomains vs. URL Path in shareable links

    - by Adam Matan
    I am building a web application for questions and answers. Each question/answer page has all the required metadata for Facebook and Twitter, and we encourage users to share these pages. I have a dilemma regarding the shared link structure: Option 1 - subdomains Use a questions.example.com and answers.example.com, followed by an ID and optional text. The text is ignored by the request, which only takes the id into account. http://questions.example.com/<question_id>/<question_text> http://questions.example.com/12345/how-long-is-the-queue # Example http://q.example.com/12345 # Example Option 2 - URL path This is the format used by stackoverflow.com and trello.com: http://example.com/questions/<question_id>/<question_text> http://example.com/questions12345/how-long-is-the-queue # Example http://example.com/q/12345 # Example Server-wise, I can easily do both - I have a wildcard SSL certificate and Apache/NGinx configuration is pretty straightforward. Which option - subdomains or URL path - is preferred for shareble links?

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  • Windows 7 booting and startup repair issues

    - by aardvark
    I have a MSI FR720 laptop with Windows 7 and Lubuntu partions. For quite a while (6 months or so) I've been having issues booting from my hard drive, it'd take me between 5 minutes and several hours for me to be able to have it recognize the hard drive as a bootable device. I did several disk checks on it, and my hard drive seems in perfect condition, and the fact that booting would usually only work after removing the hard drive and trying to reset it in its slot or lightly shaking it makes me think it had something to do with the connection in the hard drive slot as opposed to the hard drive itself. I was having particular issues with it detecting the hard drive today so I decided to try booting it from an external hard drive dock. It detected it first try and so far has had no problems finding the bootable partitions on my hard drive. When I selected my Windows 7 partition from the boot menu it said that it hadn't been shut down properly last time and needed startup repair. I've done this several times over the last 6 months, so this is hardly unusual. I do startup repair, it fails, and then I try to do a system restore. The system restore also failed, and it says that no files were changed. I restart and try it again. However, this time when I get to the startup repair it's not detecting a Windows OS. I tried clicking next and doing a startup repair but the repair is always failing. If I ignore the startup repair option and instead select "Launch windows normally" it will get to the windows animation, stop halfway through and then crash into a BSoD. I can't read the error on the screen because it immediately switches to back and tries to restart. This is my first time asking a question like this online, so let me know if I need to provide any extra information and I'll do my best to give it I tried using diskpart to find the list of partitions and see if one's labelled as an active partition, but it says that no disk were detected. I can run Lubuntu just fine. I can also see all of my Windows 7 files from it EDIT: The startup repair diagnosis and repair log is this: -- Number of repair attempts: 1 Session details System Disk = Windows directory = AutoChk Run = 0 Number of root causes = 1 Test Performed: Name: Check for updates Result: Completed successfully. Error code = 0x0 Time taken = 15ms Test Performed: Name: System disk test Result: Completed successfully. Error code = 0x0 Time taken = 31ms Root cause found. If a hard disk is installed, it is not responding. -- Any chance that this is a result of me doing this through an external dock through a USB drive?

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  • External 1TB WD USB 3.0 HDD is not detecting. Working perfectly find in Windows

    - by Yathi
    My 1TB USB 3.0 was working fine earlier in Ubuntu as well as Windows. But lately it is not at all being detected in Ubuntu. It still works fine in Windows. I did update my Ubuntu to 12.10 but I am not sure if that caused the issue. When I connect my HDD and run dmesg | tail: [ 47.804676] usb 4-3: >Device not responding to set address. [ 48.008575] usb 4-3: >Device not responding to set address. [ 48.212421] usb 4-3: >device not accepting address 9, error -71 [ 48.324451] usb 4-3: >Device not responding to set address. [ 48.528340] usb 4-3: >Device not responding to set address. [ 48.732165] usb 4-3: >device not accepting address 10, error -71 [ 48.844138] usb 4-3: >Device not responding to set address. [ 49.048179] usb 4-3: >Device not responding to set address. [ 49.251881] usb 4-3: >device not accepting address 11, error -71 [ 49.251907] hub 4-0:1.0: >unable to enumerate USB device on port 3 The output of sudo fdisk -l is : Disk /dev/sda: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0x00030cde Device Boot Start End Blocks Id System /dev/sda1 2048 1332981759 666489856 83 Linux /dev/sda2 1332981760 1953523711 310270976 5 Extended /dev/sda5 1332983808 1349365759 8190976 82 Linux swap / Solaris /dev/sda6 1349367808 1953523711 302077952 7 HPFS/NTFS/exFAT Disk /dev/sdb: 120.0 GB, 120034123776 bytes 255 heads, 63 sectors/track, 14593 cylinders, total 234441648 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000a2519 Device Boot Start End Blocks Id System /dev/sdb1 * 2048 103368703 51683328 7 HPFS/NTFS/exFAT /dev/sdb2 103368704 154568703 25600000 83 Linux /dev/sdb3 154568704 234440703 39936000 7 HPFS/NTFS/exFAT /dev/sda and /dev/sdb are my 2 internal HDDs. But the external one which should be /dev/sdc is not even being shown though it is connected and the LED on the HDD is glowing. Someone had suggested adding blacklist uas to /etc/modprobe.d/blacklist.conf. Tried that as well. But still not working. Can someone help me out.

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  • LOB Pointer Indexing Proposal

    - by jchang
    My observations are that IO to lob pages (and row overflow pages as well?) is restricted to synchronous IO, which can result in serious problems when these reside on disk drive storage. Even if the storage system is comprised of hundreds of HDDs, the realizable IO performance to lob pages is that of a single disk, with some improvement in parallel execution plans. The reason for this appears to be that each thread must work its way through a page to find the lob pointer information, and then generates...(read more)

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  • C - circular character buffer w/ pthreads

    - by Matt
    I have a homework assignment where I have to implement a circular buffer and add and remove chars with separate threads: #include <pthread.h> #include <stdio.h> #define QSIZE 10 pthread_cond_t full,/* count == QSIZE */ empty,/* count == 0 */ ready; pthread_mutex_t m, n; /* implements critical section */ unsigned int iBuf, /* tail of circular queue */ oBuf; /* head of circular queue */ int count; /* count characters */ char buf [QSIZE]; /* the circular queue */ void Put(char s[]) {/* add "ch"; wait if full */ pthread_mutex_lock(&m); int size = sizeof(s)/sizeof(char); printf("size: %d", size); int i; for(i = 0; i < size; i++) { while (count >= QSIZE) pthread_cond_wait(&full, &m);/* is there empty slot? */ buf[iBuf] = s[i]; /* store the character */ iBuf = (iBuf+1) % QSIZE; /* increment mod QSIZE */ count++; if (count == 1) pthread_cond_signal(&empty);/* new character available */ } pthread_mutex_unlock(&m); } char Get() {/* remove "ch" from queue; wait if empty */ char ch; pthread_mutex_lock(&m); while (count <= 0) pthread_cond_wait(&empty, &m);/* is a character present? */ ch = buf[oBuf]; /* retrieve from the head of the queue */ oBuf = (oBuf+1) % QSIZE; count--; if (count == QSIZE-1) pthread_cond_signal(&full);/* signal existence of a slot */ pthread_mutex_unlock(&m); return ch; } void * p1(void *arg) { int i; for (i = 0; i < 5; i++) { Put("hella"); } } void * p2(void *arg) { int i; for (i = 0; i < 5; i++) { Put("goodby"); } } int main() { pthread_t t1, t2; void *r1, *r2; oBuf = 0; iBuf = 0; count=0; /* all slots are empty */ pthread_cond_init(&full, NULL); pthread_cond_init(&empty, NULL); pthread_mutex_init(&m, NULL); pthread_create(&t1, NULL, p1, &r1); pthread_create(&t2, NULL, p2, &r2); printf("Main"); char c; int i = 0; while (i < 55) { c = Get(); printf("%c",c); i++; } pthread_join(t1, &r1); pthread_join(t2, &r2); return 0; } I shouldn't have to change the logic much at all, the requirements are pretty specific. I think my problem lies in the Put() method. I think the first thread is going in and blocking the critical section and causing a deadlock. I was thinking I should make a scheduling attribute? Of course I could be wrong. I am pretty new to pthreads and concurrent programming, so I could really use some help spotting my error.

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