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  • Problems when loop over a series of ssh-ed commands

    - by Jack Medley
    I have a series of server machines which I want to run the same command on. Each command takes hours and (even though I am running the commands using nohup and setting them to run in the background) I have to wait for each to finish before the next starts. Here is roughly how I have set it up: On the host machines: for i in {1..9}; do ssh RemoteMachine${i} ./RunJobs.sh; done Where RunJobs.sh on each remote machine is: source ~/.bash_profile cd AriadneMatching for file in FileDirectory/Input_*; do nohup ./Executable ${file} & done exit Does anyone know of a way such that I dont have to wait for each job to finish before the next starts? Or alternatively a better way of doing this, I have a feeling what I am do is fairly sub-optimal. Cheers, Jack

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  • Catch headset pause/play keypresses in Windows

    - by akshay2000
    I have a new Ultrabook which has single audio jack for input and output instead for separate 3.5 mm jacks we used to have on older machines. The jack is probably similar to American Audio Jack specification or like the one found on Macbook Pro. I have tried to use it with the Apple, HTC, Nokia earphones which ship with most of the smartphones. Microphone on the headset works the way it should. Thing is that the headsets also come with remote controls to control volume and playback. I am sure that those key presses are sent to the Windows. I was hoping to catch those events and bind those to actual media keys so that I can control music playback. I guess this happens on Macs. I want to do the similar thing on the Windows. I'm just not sure where I can catch the events. Driver level? Application level?

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  • Quick CPU ring mode protection question

    - by b-gen-jack-o-neill
    Hi, me again :) I am very curious in messing up with HW. But my top level "messing" so far was linked or inline assembler in C program. If my understanding of CPU and ring mode is right, I cannot directly from user mode app access some low level CPU features, like disabling interrupts, or changing protected mode segments, so I must use system calls to do everything I want. But, if I am right, drivers can run in ring mode 0. I actually don´t know much about drivers, but this is what I ask for. I just want to know, is learning how to write your own drivers and than call them the way I should go, to do what I wrote? I know I could write whole new OS (at least to some point), but what I exactly want to do is acessing some low level features of HW from standart windows application. So, is driver the way to go?

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  • Why am I getting a segmentation fault?

    - by Phenom
    If I pass a value greater than 100 as the second argument to BinaryInsertionSort, I get a segmentation fault. int BinarySearch (int a[], int low, int high, int key) { int mid; if (low == high) return low; mid = low + ((high - low) / 2); if (key > a[mid]) return BinarySearch (a, mid + 1, high, key); else if (key < a[mid]) return BinarySearch (a, low, mid, key); return mid; } void BinaryInsertionSort (int a[], int n) { int ins, i, j; int tmp; for (i = 1; i < n; i++) { ins = BinarySearch (a, 0, i, a[i]); if (ins < i) { tmp = a[i]; memmove (a + ins + 1, a + ins, sizeof (int) * (i - ins)); a[ins] = tmp; } } }

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  • generic binary Search in c#

    - by Pro_Zeck
    Below is my Generic Binary Search it works ok with the intgers type array it finds all the elements in it . But the Problem Arises when i use a string array to find any string data. It runs ok for the first index and last index elements but i cant find the middle elements. Stringarray = new string[] { "b", "a", "ab", "abc", "c" }; public static void BinarySearch<T>(T[] array, T searchFor, Comparer<T> comparer) { int high, low, mid; high = array.Length - 1; low = 0; if (array[0].Equals(searchFor)) Console.WriteLine("Value {0} Found At Index {1}",array[0],0); else if (array[high].Equals(searchFor)) Console.WriteLine("Value {0} Found At Index {1}", array[high], high); else { while (low <= high) { mid = (high + low) / 2; if (comparer.Compare(array[mid], searchFor) == 0) { Console.WriteLine("Value {0} Found At Index {1}", array[mid], mid); break; } else { if (comparer.Compare(searchFor, array[mid]) > 0) high = mid + 1; else low = mid + 1; } } if (low > high) { Console.WriteLine("Value Not Found In the Collection"); } } }

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  • Limit WebClient DownloadFile maximum file size

    - by Jack Juiceson
    Hi everyone, In my asp .net project, my main page receives URL as a parameter I need to download internally and then process it. I know that I can use WebClient's DownloadFile method however I want to avoid malicious user from giving a url to a huge file, which will unnecessary traffic from my server. In order to avoid this, I'm looking for a solution to set maximum file size that DownloadFile will download. Thank you in advance, Jack

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  • iPhone text editor syntax highlight

    - by Jack
    Hi, As the title suggests, I am trying to add a text editor with syntax highlighting to a project. I have asked a similar question before and got pointed in the direction of either: a) a UITextView and NSAttributedStrings Or b) a web view Can anyone shed some light on using either of These methods or suggest an alternative? I have searched around for a few hours now and have found nothing. Jack

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  • Python. How to iterate through a list of lists looking for a partial match

    - by Becca Millard
    I'm completely stuck on this, without even an idea about how to wrap my head around the logic of this. In the first half of the code, I have successfully generation a list of (thousands of) lists of players names and efficiency scores: eg name_order_list = [["Bob", "Farley", 12.345], ["Jack", "Donalds", 14.567], ["Jack", "Donalds", 13.421], ["Jack", "Donalds", 15.232],["Mike", "Patricks", 10.543]] What I'm trying to do, is come up with a way to make a list of lists of the average efficiency of each player. So in that example, Jack Donalds appears multiple times, so I'd want to recognize his name somehow and average out the efficiency scores. Then sort that new list by efficiency, rather than name. So then the outcome would be like: average_eff_list = [[12.345, "Bob", "Farley"], [14.407, "Jack", "Donalds"], [10.543, "Mike", "Patricks"]] Here's what I tried (it's kind of a mess, but should be readable): total_list = [] odd_lines = [name_order_list[i] for i in range(len(name_order_list)) if i % 2 == 0] even_lines = [name_order_list[i] for i in range(len(name_order_list)) if i % 2 == 1] i = 0 j = i-1 while i <= 10650: iteration = 2 total_eff = 0 while odd_lines[i][0:2] == even_lines[i][0:2]: if odd_lines[i][0:2] == even_lines[j][0:2]: if odd_lines[j][0:2] != even_lines[j][0:2]: total_eff = even_lines[j][2]/(iteration-1) iteration -= 1 #account fr the single (rather than dual) additional entry else: total_eff = total_eff if iteration == 2: total_eff = (odd_lines[i][2] + even_lines[i][2]) / iteration else: total_eff = ((total_eff * (iteration - 2)) + (odd_lines[i][2] + even_lines[i][2])) / iteration iteration += 2 i += 1 j += 1 if i > 10650: break else: if odd_lines[i][0:2] == even_lines[j][0:2]: if odd_lines[j][0:2] != even_lines[j][0:2]: total_eff = (odd_lines[i][2] + even_lines[j][2]) / iteration else: total_eff = ((total_eff * (iteration -2)) + odd_lines[i][2]) / (iteration - 1) if total_eff == 0: #there's no match at all total_odd = [odd_lines[i][2], odd_lines[i][0], odd_lines[i][1]] total_list.append(total_odd) if even_lines[i][0:2] != odd_lines[i+1][0:2]: total_even = [even_lines[i][2], even_lines[i][0], even_lines[i][1]] else: total = [total_eff, odd_lines[i][0], odd_lines[i][1]] total_list.append(total) i += 1 if i > 10650: break else: print(total_list) Now, this runs well enough (doesn't get stuck or print someone's name multiple times) but the efficiency values are off by a large amount, so I know that scores are getting missed somewhere. This is a problem with my logic, I think, so any help would be greatly appreciated. As would any advice about how to loop through that massive list in a smarter way, since I'm sure there is one... EIDT: for this exercise, I need to keep it all in a list format. I can make new lists, but no using dictionaries, classes, etc.

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  • iPhone app distribution: What name will appear on the AppStore?

    - by Jack Griffiths
    Hi there, Is there a way to change the name that displays on the AppStore, rather than the name associated with the credit card/apple ID associated with the developer programme? For example, if my name on my credit card was foo, and the name on the apple ID was foo, but I actually want the name displayed on the AppStore (i.e. next to my App's name and details) to be bar. BTW: The programme is individual. Many thanks, Jack

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  • After my laptop wakes up from sleeping/hibernating, the LCD/brightness is very low. How can I set it to default?

    - by meder
    In Power Management Preferences, On AC Power tab, I have brightness to 100%. "Dim display when idle" is not checked. I know for sure my LCD brightness is capable of going higher, because if I hit Fn and F7 then it resets the monitor brightness and settings for a few seconds, but the resolution breaks and then the brightness goes back. PS: OS is Debian Lenny ( I set the tags but for clarification ) and laptop is a Thinkpad.

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  • Very high CPU and low RAM usage - is it possible to place some of swap some of the CPU usage to the RAM (with CloudLinux LVE Manager installed)?

    - by Chriswede
    I had to install CloudLinux so that I could somewhat controle the CPU ussage and more importantly the Concurrent-Connections the Websites use. But as you can see the Server load is way to high and thats why some sites take up to 10 sec. to load! Server load 22.46 (8 CPUs) (!) Memory Used 36.32% (2,959,188 of 8,146,632) (ok) Swap Used 0.01% (132 of 2,104,504) (ok) Server: 8 x Intel(R) Xeon(R) CPU E31230 @ 3.20GHz Memory: 8143680k/9437184k available (2621k kernel code, 234872k reserved, 1403k data, 244k init) Linux Yesterday: Total of 214,514 Page-views (Awstat) Now my question: Can I shift some of the CPU usage to the RAM? Or what else could I do to make the sites run faster (websites are dynamic - so SQL heavy) Thanks top - 06:10:14 up 29 days, 20:37, 1 user, load average: 11.16, 13.19, 12.81 Tasks: 526 total, 1 running, 524 sleeping, 0 stopped, 1 zombie Cpu(s): 42.9%us, 21.4%sy, 0.0%ni, 33.7%id, 1.9%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 8146632k total, 7427632k used, 719000k free, 131020k buffers Swap: 2104504k total, 132k used, 2104372k free, 4506644k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 318421 mysql 15 0 1315m 754m 4964 S 474.9 9.5 95300:17 mysqld 6928 root 10 -5 0 0 0 S 2.0 0.0 90:42.85 kondemand/3 476047 headus 17 0 172m 19m 10m S 1.7 0.2 0:00.05 php 476055 headus 18 0 172m 18m 9.9m S 1.7 0.2 0:00.05 php 476056 headus 15 0 172m 19m 10m S 1.7 0.2 0:00.05 php 476061 headus 18 0 172m 19m 10m S 1.7 0.2 0:00.05 php 6930 root 10 -5 0 0 0 S 1.3 0.0 161:48.12 kondemand/5 6931 root 10 -5 0 0 0 S 1.3 0.0 193:11.74 kondemand/6 476049 headus 17 0 172m 19m 10m S 1.3 0.2 0:00.04 php 476050 headus 15 0 172m 18m 9.9m S 1.3 0.2 0:00.04 php 476057 headus 17 0 172m 18m 9.9m S 1.3 0.2 0:00.04 php 6926 root 10 -5 0 0 0 S 1.0 0.0 90:13.88 kondemand/1 6932 root 10 -5 0 0 0 S 1.0 0.0 247:47.50 kondemand/7 476064 worldof 18 0 172m 19m 10m S 1.0 0.2 0:00.03 php 6927 root 10 -5 0 0 0 S 0.7 0.0 93:52.80 kondemand/2 6929 root 10 -5 0 0 0 S 0.3 0.0 161:54.38 kondemand/4 8459 root 15 0 103m 5576 1268 S 0.3 0.1 54:45.39 lvest

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  • save xml object so that elements are in sorted order in saved xml file

    - by scot
    Hi , I am saving a xml document object and it is saved in a xml file as shown below . <author name="tom" book="Fun-II"/> <author name="jack" book="Live-I"/> <author name="pete" book="Code-I"/> <author name="jack" book="Live-II"/> <author name="pete" book="Code-II"/> <author name="tom" book="Fun-I"/> instead i want to sort the content in document object so that when i persist the object it is saved by grouping authors then book name as below: <author name="jack" book="Live-I"/> <author name="jack" book="Live-II"/> <author name="pete" book="Code-I"/> <author name="pete" book="Code-II"/> <author name="tom" book="Fun-I"/> <author name="tom" book="Fun-II"/> I use apache xml beans..any ideas on how to achieve this? thanks.

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  • Excel VBA Text To Column

    - by Pat
    This is what I currently have: H101 John Doe Jane Doe Jack Doe H102 John Smith Jane Smith Katie Smith Jack Smith And here is what I want: H101 John Doe H101 Jane Doe H101 Jack Doe H102 John Smith H102 Jane Smith H102 Katie Smith H102 Jack Smith Obviously I want to do this on a bigger scale. The number of columns is between 1 & 6, so I cant limit it that way. I was able to get a script that allows me to put each individual on one row. However, I am having a hard time getting the first column to copy over to each row. Sub ToOneColumn() Dim i As Long, k As Long, j As Integer Application.ScreenUpdating = False Columns(2).Insert i = 0 k = 1 While Not IsEmpty(Cells(k, 3)) j = 3 While Not IsEmpty(Cells(k, j)) i = i + 1 Cells(i, 1) = Cells(k, 1) //CODE IN QUESTION Cells(i, 2) = Cells(k, j) Cells(k, j).Clear j = j + 1 Wend k = k + 1 Wend Application.ScreenUpdating = True End Sub Like I said, it was working fine to get everyone each on their own row, but can't figure out how to get that first column. It seems like it should be so simple, but it's bugging me. Any help is greatly appreciated.

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  • PHP - post data ends when '&' is in data.

    - by Phil Jackson
    Hi all, im posting data using jquery/ajax and PHP at the backend. Problem being, when I input something like 'Jack & Jill went up the hill' im only recieving 'Jack' when it gets to the backend. I have thrown an error at the frontend before that data is sent which alerts 'Jack & Jill went up the hill'. When I put die(print_r($_POST)); at the very top of my index page im only getting [key] => Jack how can I be loosing the data? I thought It may have been my filter; <?php function filter( $data ) { $data = trim( htmlentities( strip_tags( mb_convert_encoding( $data, 'HTML-ENTITIES', "UTF-8") ) ) ); if ( get_magic_quotes_gpc() ) { $data = stripslashes( $data ); } //$data = mysql_real_escape_string( $data ); return $data; } echo "<xmp>" . filter("you & me") . "</xmp>"; ?> but that returns fine in the test above you &amp; me which is in place after I added die(print_r($_POST));. Can anyone think of how and why this is happening? Any help much appreciated. Regards, Phil.

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  • Troubleshoot dropped wireless connections

    - by Jack
    I was recently hired in the IT department of a small company (~180 users) and one of the issues that people have been complaining about is having their wi-fi connections drop during meetings. The company is using an HP ProCurve Wireless LAN with 10 APs and a controller unit located in the server room. I don't have any experience troubleshooting WLAN in a multi-AP environment, so I'm trying to at least gather information using free or cheap tools. I did a basic site survey using the free version of Ekahau HeatMapper and discovered the following in one of the conference rooms that has been a problem. The program picked up three access points (plus a bunch of others with much lower signals that were out of range): AP 1: SSID: "Unknown SSID" - Signal strength: -48 dBm - -40 dBm. Channel: 2 AP 2: SSID "CompanyMain" - Signal strength: -35 dBm or greater. Channel: 2. Security: WEP (This is the main SSID for the company's WLAN.) AP 3: SSID: "CompanyGuest" - Signal strength: -40 dBm - -35 dBm. Channel: 2. Security: WPA2 (This SSID is the company's "guest" WLAN, which was setup to allow Internet access, but prevent network access.) Is there anything that you see that is clearly a problem from the above? I'm assuming that the unknown SSID might be a big problem, and that it is an AP from a neighboring office that is causing interference. Does that seem likely? Also, regarding channel, should we try changing the channels of our APs to avoid interference with that unknown SSID? (Since everything seems to be on Channel 2?) Should our APs be on different channels? In other words, should the CompanyMain and CompanyGuest APs be on different channels? Finally, any recommendations for free/cheap tools to help me figure this out, and/or a good methodology to follow? Thanks in advance for any help. Jack

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  • Parallels Plesk returning strange numbers

    - by Jack W-H
    Hi everyone, As a relatively new Server Admin I've become a bit confused by some statistics Parallels Plesk Panel 10.0.1 is returning to me. I have a domain ('subscription') set up, mysite.com. Mysite.com only hosts files, mostly images Its file contents use up about 390MB of disk space Here's a screenshot: this is what Plesk is reporting mysite.com to use: And some more info: Now this is pretty confusing... I thought at first my site might have been hacked and had contents written to disk, but I checked and all is in order, nothing has been hacked into as far as I can tell. So I had a look in the site's CP for some more in-depth statistics, and this is what's returned... Now - sod's law - when I go to check my disk space statistics in more depth via the control panel, this morning it says "The data were not collected yet." - not too sure what that means, but, last night when I checked it was reporting something odd. It said Files were using up 390MB, but 1.80GB or so were being used up by 'Mail Accounts'. This is really strange, as there are no mail accounts set up for the domain. The only hint of 'mail' there is, is the catchall set up to forward *@mysite.com to a separate, ISP-hosted email account. Any ideas anybody? I can post more details if you need it. Sorry to be a bit vague but I'm not sure what else I can post. Thanks, Jack

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  • Why Does Private Access Remain Non-Private in .NET Within a Class?

    - by AMissico
    While cleaning some code today written by someone else, I changed the access modifier from Public to Private on a class variable/member/field. I expected a long list of compiler errors that I use to "refactor/rework/review" the code that used this variable. Imagine my surprise when I didn't get any errors. After reviewing, it turns out that another instance of the Class can access the private members of another instance declared within the Class. Totally unexcepted. Is this normal? I been coding in .NET since the beginning and never ran into this issue, nor read about it. I may have stumbled onto it before, but only "vaguely noticed" and move on. Can anyone explain this behavoir to me? Am I doing something wrong? I found this behavior in both C# and VB.NET. The code seems to take advantage of the ability to access private variables. Sincerely, Totally Confused Class Foo Private _int As Integer Private _foo As Foo Private _jack As Jack Private _fred As Fred Public Sub SetPrivate() _foo = New Foo _foo._int = 3 'TOTALLY UNEXPECTED _jack = New Jack '_jack._int = 3 'expected compile error because Foo doesn't know Jack _fred = New Fred '_fred._int = 3 'expected compile error because Fred hides from Foo End Sub Private Class Fred Private _int As Integer End Class End Class Class Jack Private _int As Integer End Class

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  • Get nested item from XML with jQuery

    - by Dkong
    I've looked at some examples on the web but I am still struggling with this. I would like to get the value for "descShort" tag within the "indexDesc" tag and then after that display the value from the "last" tag? I've seen people using the arrow but I'm still lost. <indices> <index> <code>DJI</code> <exchange>NYSE</exchange> <liveness>DELAYED</liveness> <indexDesc> <desc>Dow Jones Industrials</desc> <descAbbrev>DOW JONES</descAbbrev> <descShort>DOW JONES</descShort> <firstActive></firstActive> <lastActive></lastActive> </indexDesc> <indexQuote> <capital> <first>11144.57</first> <high>11153.79</high> <low>10973.92</low> <last>11018.66</last> <change>-125.9</change> <pctChange>-1.1%</pctChange> </capital> <gross> <first>11144.57</first> <high>11153.79</high> <low>10973.92</low> <last>11018.66</last> <change>-125.9</change> <pctChange>-1.1%</pctChange> </gross> <totalEvents>4</totalEvents> <lastChanged>16-Apr-2010 16:03:00</lastChanged> </indexQuote> </index> <index> <code>XAO</code> <exchange>ASX</exchange> <liveness>DELAYED</liveness> <indexDesc> <desc>ASX All Ordinaries</desc> <descAbbrev>All Ordinaries</descAbbrev> <descShort>ALL ORDS</descShort> <firstActive>06-Mar-1970</firstActive> <lastActive></lastActive> </indexDesc> <indexQuote> <capital> <first>5007.30</first> <high>5007.30</high> <low>4934.00</low> <last>4939.40</last> <change>-67.9</change> <pctChange>-1.4%</pctChange> </capital> <gross> <first>5007.30</first> <high>5007.30</high> <low>4934.00</low> <last>4939.40</last> <change>-67.9</change> <pctChange>-1.4%</pctChange> </gross> <totalEvents>997</totalEvents> <lastChanged>19-Apr-2010 17:02:54</lastChanged> </indexQuote> </index> </indices>

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  • How much RAM 64bit Windows 8 reserves to OS internal use?

    - by Barleyman
    Windows reserves some memory for it's internal use which is not normally allocated to applications. This reserve is seen most easily if you run without a page file or limit the pagefile to relatively small size (such as 3GB). Windows will allocate primarily RAM up to the limit, fill up remaining free space in the page file (if any) and issue a low memory warning when there is no page file space left and the allocated RAM limit is exceeded. The limit appears to be a percentage of the total system RAM. Windows 7 x64 limit is discussed here and methods for circumventing the "low memory warning" is discussed here. Disabling the low memory warning has some advantages - You can use some 600MB more RAM on 8GB machine) But there is a serious disadvantage - When you're out of ram, programs will crash. How much RAM can you allocate on 8GB Windows 8 x64 before you get the low memory warning? Is it possible to adjust the warning threshold?

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  • Android Signal analysis + some filters.

    - by Profete162
    Hello, as the world cup is the main sport event and the Vuvuzelas are the most annoying sound in the world, I had an idea to remove them definitively by reading this new ( http://www.popsci.com/diy/article/2010-06/simple-software-can-filter-out-vuvuzela-whine) that told us that the sound has some frequencies at 233Hz + 466,932,1864Hz. I have already made a lot of Android application by myself but never touching the signal analysis and filtering part, so here are a few questions, I do not ask for precise answer but maybe links and tutorial to find something to work on. I guess that a new Android phone has the CPU and power to make real-time filtering. 1) How can I intercept the sound coming from the Jack microphone - Line-IN plug- ( I plan to link my TV to my phone with Jack to Jack plug). My question is totally software and coding, I have all the wires and adapters to plug a jack into my android phone Line IN. 2) Are there some Fourier analysis librairies, may I have a look to Java libraries on the web and import them to my Android project? I really apologize because my question seem not precise, but I think that would be something great. Thank you for your answers.

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  • SQL Server and Hyper-V Dynamic Memory Part 2

    - by SQLOS Team
    Part 1 of this series was an introduction and overview of Hyper-V Dynamic Memory. This part looks at SQL Server memory management and how the SQL engine responds to changing OS memory conditions.   Part 2: SQL Server Memory Management As with any Windows process, sqlserver.exe has a virtual address space (VAS) of 4GB on 32-bit and 8TB in 64-bit editions. Pages in its VAS are mapped to pages in physical memory when the memory is committed and referenced for the first time. The collection of VAS pages that have been recently referenced is known as the Working Set. How and when SQL Server allocates virtual memory and grows its working set depends on the memory model it uses. SQL Server supports three basic memory models:   1. Conventional Memory Model   The Conventional model is the default SQL Server memory model and has the following properties: - Dynamic - can grow or shrink its working set in response to load and external (operating system) memory conditions. - OS uses 4K pages – (not to be confused with SQL Server “pages” which are 8K regions of committed memory).- Pageable - Can be paged out to disk by the operating system.   2. Locked Page Model The locked page memory model is set when SQL Server is started with "Lock Pages in Memory" privilege*. It has the following characteristics: - Dynamic - can grow or shrink its working set in the same way as the Conventional model.- OS uses 4K pages - Non-Pageable – When memory is committed it is locked in memory, meaning that it will remain backed by physical memory and will not be paged out by the operating system. A common misconception is to interpret "locked" as non-dynamic. A SQL Server instance using the locked page memory model will grow and shrink (allocate memory and release memory) in response to changing workload and OS memory conditions in the same way as it does with the conventional model.   This is an important consideration when we look at Hyper-V Dynamic Memory – “locked” memory works perfectly well with “dynamic” memory.   * Note in “Denali” (Standard Edition and above), and in SQL 2008 R2 64-bit (Enterprise and above editions) the Lock Pages in Memory privilege is all that is required to set this model. In 2008 R2 64-Bit standard edition it also requires trace flag 845 to be set, in 2008 R2 32-bit editions it requires sp_configure 'awe enabled' 1.   3. Large Page Model The Large page model is set using trace flag 834 and potentially offers a small performance boost for systems that are configured with large pages. It is characterized by: - Static - memory is allocated at startup and does not change. - OS uses large (>2MB) pages - Non-Pageable The large page model is supported with Hyper-V Dynamic Memory (and Hyper-V also supports large pages), but you get no benefit from using Dynamic Memory with this model since SQL Server memory does not grow or shrink. The rest of this article will focus on the locked and conventional SQL Server memory models.   When does SQL Server grow? For “dynamic” configurations (Conventional and Locked memory models), the sqlservr.exe process grows – allocates and commits memory from the OS – in response to a workload. As much memory is allocated as is required to optimally run the query and buffer data for future queries, subject to limitations imposed by:   - SQL Server max server memory setting. If this configuration option is set, the buffer pool is not allowed to grow to more than this value. In SQL Server 2008 this value represents single page allocations, and in “Denali” it represents any size page allocations and also managed CLR procedure allocations.   - Memory signals from OS. The operating system sets a signal on memory resource notification objects to indicate whether it has memory available or whether it is low on available memory. If there is only 32MB free for every 4GB of memory a low memory signal is set, which continues until 64MB/4GB is free. If there is 96MB/4GB free the operating system sets a high memory signal. SQL Server only allocates memory when the high memory signal is set.   To summarize, for SQL Server to grow you need three conditions: a workload, max server memory setting higher than the current allocation, high memory signals from the OS.    When does SQL Server shrink caches? SQL Server as a rule does not like to return memory to the OS, but it will shrink its caches in response to memory pressure. Memory pressure can be divided into “internal” and “external”.   - External memory pressure occurs when the operating system is running low on memory and low memory signals are set. The SQL Server Resource Monitor checks for low memory signals approximately every 5 seconds and it will attempt to free memory until the signals stop.   To free memory SQL Server does the following: ·         Frees unused memory. ·         Notifies Memory Manager Clients to release memory o   Caches – Free unreferenced cache objects. o   Buffer pool - Based on oldest access times.   The freed memory is released back to the operating system. This process continues until the low memory resource notifications stop.    - Internal memory pressure occurs when the size of different caches and allocations increase but the SQL Server process needs to keep its total memory within a target value. For example if max server memory is set and certain caches are growing large, it will cause SQL to free memory for re-use internally, but not to release memory back to the OS. If you lower the value of max server memory you will generate internal memory pressure that will cause SQL to release memory back to the OS.    Memory pressure handling has not changed much since SQL 2005 and it was described in detail in a blog post by Slava Oks.   Note that SQL Server Express is an exception to the above behavior. Unlike other editions it does not assume it is the most important process running on the system but tries to be more “desktop” friendly. It will empty its working set after a period of inactivity.   How does SQL Server respond to changing OS memory?    In SQL Server 2005 support for Hot-Add memory was introduced. This feature, available in Enterprise and above editions, allows the server to make use of any extra physical memory that was added after SQL Server started. Being able to add physical memory when the system is running is limited to specialized hardware, but with the Hyper-V Dynamic Memory feature, when new memory is allocated to a guest virtual machine, it looks like hot-add physical memory to the guest. What this means is that thanks to the hot-add memory feature, SQL Server 2005 and higher can dynamically grow if more “physical” memory is granted to a guest VM by Hyper-V dynamic memory.   SQL Server checks OS memory every second and dynamically adjusts its “target” (based on available OS memory and max server memory) accordingly.   In “Denali” Standard Edition will also have sqlserver.exe support for hot-add memory when running virtualized (i.e. detecting and acting on Hyper-V Dynamic Memory allocations).   How does a SQL Server workload in a guest VM impact Hyper-V dynamic memory scheduling?   When a SQL workload causes the sqlserver.exe process to grow its working set, the Hyper-V memory scheduler will detect memory pressure in the guest VM and add memory to it. SQL Server will then detect the extra memory and grow according to workload demand. In our tests we have seen this feedback process cause a guest VM to grow quickly in response to SQL workload - we are still working on characterizing this ramp-up.    How does SQL Server respond when Hyper-V removes memory from a guest VM through ballooning?   If pressure from other VM's cause Hyper-V Dynamic Memory to take memory away from a VM through ballooning (allocating memory with a virtual device driver and returning it to the host OS), Windows Memory Manager will page out unlocked portions of memory and signal low resource notification events. When SQL Server detects these events it will shrink memory until the low memory notifications stop (see cache shrinking description above).    This raises another question. Can we make SQL Server release memory more readily and hence behave more "dynamically" without compromising performance? In certain circumstances where the application workload is predictable it may be possible to have a job which varies "max server memory" according to need, lowering it when the engine is inactive and raising it before a period of activity. This would have limited applicaability but it is something we're looking into.   What Memory Management changes are there in SQL Server “Denali”?   In SQL Server “Denali” (aka SQL11) the Memory Manager has been re-written to be more efficient. The main changes are summarized in this post. An important change with respect to Hyper-V Dynamic Memory support is that now the max server memory setting includes any size page allocations and managed CLR procedure allocations it now represents a closer approximation to total sqlserver.exe memory usage. This makes it easier to calculate a value for max server memory, which becomes important when configuring virtual machines to work well with Hyper-V Dynamic Memory Startup and Maximum RAM settings.   Another important change is no more AWE or hot-add support for 32-bit edition. This means if you're running a 32-bit edition of Denali you're limited to a 4GB address space and will not be able to take advantage of dynamically added OS memory that wasn't present when SQL Server started (though Hyper-V Dynamic Memory is still a supported configuration).   In part 3 we’ll develop some best practices for configuring and using SQL Server with Dynamic Memory. Originally posted at http://blogs.msdn.com/b/sqlosteam/

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  • How to: Check which table is the biggest, in SQL Server

    - by AngelEyes
    The company I work with had it's DB double its size lately, so I needed to find out which tables were the biggest. I found this on the web, and decided it's worth remembering! Taken from http://www.sqlteam.com/article/finding-the-biggest-tables-in-a-database, the code is from http://www.sqlteam.com/downloads/BigTables.sql   /************************************************************************************** * *  BigTables.sql *  Bill Graziano (SQLTeam.com) *  [email protected] *  v1.1 * **************************************************************************************/ DECLARE @id INT DECLARE @type CHARACTER(2) DECLARE @pages INT DECLARE @dbname SYSNAME DECLARE @dbsize DEC(15, 0) DECLARE @bytesperpage DEC(15, 0) DECLARE @pagesperMB DEC(15, 0) CREATE TABLE #spt_space   (      objid    INT NULL,      ROWS     INT NULL,      reserved DEC(15) NULL,      data     DEC(15) NULL,      indexp   DEC(15) NULL,      unused   DEC(15) NULL   ) SET nocount ON -- Create a cursor to loop through the user tables DECLARE c_tables CURSOR FOR   SELECT id   FROM   sysobjects   WHERE  xtype = 'U' OPEN c_tables FETCH NEXT FROM c_tables INTO @id WHILE @@FETCH_STATUS = 0   BEGIN       /* Code from sp_spaceused */       INSERT INTO #spt_space                   (objid,                    reserved)       SELECT objid = @id,              SUM(reserved)       FROM   sysindexes       WHERE  indid IN ( 0, 1, 255 )              AND id = @id       SELECT @pages = SUM(dpages)       FROM   sysindexes       WHERE  indid < 2              AND id = @id       SELECT @pages = @pages + Isnull(SUM(used), 0)       FROM   sysindexes       WHERE  indid = 255              AND id = @id       UPDATE #spt_space       SET    data = @pages       WHERE  objid = @id       /* index: sum(used) where indid in (0, 1, 255) - data */       UPDATE #spt_space       SET    indexp = (SELECT SUM(used)                        FROM   sysindexes                        WHERE  indid IN ( 0, 1, 255 )                               AND id = @id) - data       WHERE  objid = @id       /* unused: sum(reserved) - sum(used) where indid in (0, 1, 255) */       UPDATE #spt_space       SET    unused = reserved - (SELECT SUM(used)                                   FROM   sysindexes                                   WHERE  indid IN ( 0, 1, 255 )                                          AND id = @id)       WHERE  objid = @id       UPDATE #spt_space       SET    ROWS = i.ROWS       FROM   sysindexes i       WHERE  i.indid < 2              AND i.id = @id              AND objid = @id       FETCH NEXT FROM c_tables INTO @id   END SELECT TOP 25 table_name = (SELECT LEFT(name, 25)                             FROM   sysobjects                             WHERE  id = objid),               ROWS = CONVERT(CHAR(11), ROWS),               reserved_kb = Ltrim(Str(reserved * d.low / 1024., 15, 0) + ' ' + 'KB'),               data_kb = Ltrim(Str(data * d.low / 1024., 15, 0) + ' ' + 'KB'),               index_size_kb = Ltrim(Str(indexp * d.low / 1024., 15, 0) + ' ' + 'KB'),               unused_kb = Ltrim(Str(unused * d.low / 1024., 15, 0) + ' ' + 'KB') FROM   #spt_space,        MASTER.dbo.spt_values d WHERE  d.NUMBER = 1        AND d.TYPE = 'E' ORDER  BY reserved DESC DROP TABLE #spt_space CLOSE c_tables DEALLOCATE c_tables

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