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  • I'm seeing a lot of a new format for title elements for major sites: a few tags, and only then the title of the site itself, is this now optimal SEO?

    - by Tchalvak
    I'm seeing a lot of sites go to a format similar to the one now in use by stackexchange sites (i.e. short topic - maybe a long topic - only finally the site's name). Is this optimal SEO? It seems kind weird both because I'm only begun to notice changes in this direction recently, and because it seems like it would make it harder to tell in search results which actual site you're visiting, even if the topic is one that matches. Still, sites like Facebook, StackOverflow, etc probably aren't wrong, so I'm wondering if I should try to make my sites use that format, going forwards...

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  • Documenting using Sandcastle: Refering to enum value using <see>

    - by brickner
    I'm using Sandcastle 2.4.10520 and Sandcastle Help File Builder 1.8.0 to generate a .chm help file. In my documentation, I'm using <see> tags. If I try to refer an enum like <see cref="NumberStyles"/> it works perfectly. If I try to refer an enum value like <see cref="NumberStyles.AllowTrailingWhite"/> I get a link in the documentation file, but the link leads me to an MSDN Page not found I don't get any warnings - my xml documentation is correct. I've noticed that MSDN pages that refer to an enum value also have a Page not found link. For example: UInt64.Parse Method (String, NumberStyles, IFormatProvider) refers to NumberStyles.AllowHexSpecifier and this leads to another MSDN Page not found. Should I refer to the enum instead of the enum value? What should I do to refer an enum? Is it even possible?

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  • How to convert this foreach loop into Linq code?

    - by a-galkin
    I am new one with Linq and I would like to modify my old c# code to use Linq. The idea of this code to select all tables where it's not set and reference’s field PrimaryTable equal "myTable" foreach (Table table in dbServer.Tables) { if (!table.IsSet) { foreach (Reference refer in table.References) { if (refer.PrimaryTable == "myTable") { tables.Add(table); } } } } After digging in internet I have got this code var q = from table in dbServer.Tables let refers = from refer in table.References where refer.PrimaryTable == "myTable" select refer.ForeignTable where refers.Contains(table.Name) select table; But it does not work at all and I need your help to make it works. Thanks in advance.

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  • Network shares do not mount.

    - by Alex
    My network shares were mounting fine yesterday.. suddenly they are not. They were mounting fine for the last two weeks or however long since I added them. When I run sudo mount -a I get the following error: topsy@monolyth:~$ sudo mount -a mount error(12): Cannot allocate memory Refer to the mount.cifs(8) manual page (e.g. man mount.cifs) mount error(12): Cannot allocate memory Refer to the mount.cifs(8) manual page (e.g. man mount.cifs) mount error(12): Cannot allocate memory Refer to the mount.cifs(8) manual page (e.g. man mount.cifs) mount error(12): Cannot allocate memory Refer to the mount.cifs(8) manual page (e.g. man mount.cifs) topsy@monolyth:~$ I followed this guide when setting them up: http://ubuntuforums.org/showthread.php?t=288534 So I tried removing them by doing the reverse, and then rebooting, then adding them again and rebooting. Problem persists.

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  • Network shares do not mount

    - by Alex
    My network shares were mounting fine yesterday.. suddenly they are not. They were mounting fine for the last two weeks or however long since I added them. When I run sudo mount -a I get the following error: topsy@monolyth:~$ sudo mount -a mount error(12): Cannot allocate memory Refer to the mount.cifs(8) manual page (e.g. man mount.cifs) mount error(12): Cannot allocate memory Refer to the mount.cifs(8) manual page (e.g. man mount.cifs) mount error(12): Cannot allocate memory Refer to the mount.cifs(8) manual page (e.g. man mount.cifs) mount error(12): Cannot allocate memory Refer to the mount.cifs(8) manual page (e.g. man mount.cifs) topsy@monolyth:~$ I followed this guide when setting them up: http://ubuntuforums.org/showthread.php?t=288534 So I tried removing them by doing the reverse, and then rebooting, then adding them again and rebooting. Problem persists.

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  • "Mac" vs "OS X" vs "Mac OS X"

    - by Brian Campbell
    I am writing server software that gives administrators options that apply only to Mac OS X clients. When naming those options, I need to decide how I am going to refer to such clients. I can see three choices: Mac OS X Mac OS X In context, I feel that "Mac OS X" might be a little clumsy: "Default protocol for Mac OS X clients"; "Change Mac OS X protocol". In discussing with my boss, he suggests "OS X", as that's the name for the OS itself, while I think that "Mac" is more recognizable. While "OS X" is technically correct and is what Apple recommends, I feel that it has a lot less name recognition than "Mac"; in particular, administrators who work in a Windows-only environment may not even recognize "OS X" and wonder what the options is about, while I think everyone knows what "Mac" refers to. In looking at what several popular pieces of software choose, I see that Microsoft has "Office for Mac". Adobe calls it "Macintosh" (which sounds very outdated, I believe that Apple stopped using that "Macintosh" years ago). Firefox uses "Mac OS X". Google has "Google Software Downloads for Mac". I don't see many popular pieces of software that refer to it solely as OS X; it seems that either "Mac OS X" or "Mac" is used most often. Apple does refer to it as OS X, but I think the fact that it's coming from Apple provides the disambiguation that you need, so it's not confusing coming from them, while it may be in another context. Is there any good solution for this? Should I just use the somewhat clumsy "Mac OS X" everywhere (or at least, the first time I refer to it in any given screen)? Obviously, my boss has final say, but I'd like to be able to provide a coherent argument.

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  • What is a generic term for name/identifier? (as opposed to label)

    - by d3vid
    I need to refer to a number of things that have both an identifier value (used in code and configuration), and a human-readable label. These things include: database columns dropdown items subapplications objects stored in a dictionary I want two unambiguous terms. One to refer to the identifier/value/key. One to refer to the label. As you can see, I'm pretty settled on the latter :) For the former, identifier seems best (not everything is strictly a key, and value and name could refer to the label; although, identifier usually refers only to a variable name), but I would prefer to follow an established practice if there is one. Is there an established term for this? (Please provide a source.) If not, are there any examples of a choice from a significant source (Java APIs, MSDN, a big FLOSS project)? (I wasn't sure if this should be posted here or to English Language & Usage. I thought this was the more appropriate expert audience. Happy to migrate if not.)

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  • import hotmail contacts using asp.net

    - by refer
    i need to import live/hotmail contacts using asp.net. I have done gmail and yahoo. i looked at opencontactsnet.dll and it doesnt work for live. none of the contacts are retrieved from that dll. does anyone know anything specifically for hotmail contacts?

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  • dataset using where condition from another query

    - by refer
    here's my code. I have a dataset that has its values and then i run an independent query which uses the same tables as dataset. now when i run the dataset, i want it to get a where condition on the query result. here's the code - sql = "SELECT ID, name FROM books WITH(NOLOCK) WHERE id =" & Session("ID") ds = FillDataset(sql) Sql1 = "SELECT n.id as id,a.name as title FROM books n WITH(NOLOCK)" & _ "LEFT JOIN new_books a WITH(NOLOCK) ON a.id = n.book_id " rd = ExecuteReader(SqlCnn, SqlStr) Now after this i make an htmltable and all the cells are loaded with the data from datareader(rd). but 1 dropdown is loaded from the dataset. i want that dropdown to have the selectedvalue which is the value from the datareader(rd). how can i do that?

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  • How to upload a CSV file and and read it's data in the client side itself and send the data as a stream through a ajax post?

    - by sunshine
    I need to upload a CSV file and get its contents form the client side itself. Then post it to the server where I can retriev the stream and do the string manipulations in the serer action methods. Is there any jquery plugin for this task to upload a csv file and send data as a stream using ajax or jason? I am really new to this area.I am working in VS2010 AND mvc3. Can some one give me a clear solution for this mater?? Any examples?? I did search a lot but did not find any suitable solution yet. Can anyone please help me with this matter. Thanks so much.

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  • Not All “Viruses” Are Viruses: 10 Malware Terms Explained

    - by Chris Hoffman
    Most people seem to call every type of malware a “virus”, but that isn’t technically accurate. You’ve probably heard of many more terms beyond virus: malware, worm, Trojan, rootkit, keylogger, spyware, and more. But what do all these terms mean? These terms aren’t just used by geeks. They make their way into even mainstream news stories about the latest web security problems and tech scares. Understanding them will help you understand the dangers your\ hear about. Malware The word “malware” is short for “malicious software.” Many people use the word “virus” to indicate any type of harmful software, but a virus is actually just a specific type of malware. The word “malware” encompasses all harmful software, including all the ones listed below. Virus Let’s start with viruses. A virus is a type of malware that copies itself by infecting other files,  just as viruses in the real world infect biological cells and use those biological cells to reproduce copies of themselves. A virus can do many different things — watch in the background and steal your passwords, display advertisements, or just crash your computer — but the key thing that makes it a virus is how it spreads. When you run a virus, it will infect programs on your computer. When you run the program on another computer, the virus will infect programs on that computer, and so on. For example, a virus might infect program files on a USB stick. When the programs on that USB stick are run on another computer, the virus runs on the other computer and infects more program files. The virus will continue to spread in this way. Worm A worm is similar to a virus, but it spreads a different way. Rather than infecting files and relying on human activity to move those files around and run them on different systems, a worm spreads over computer networks on its own accord. For example, the Blaster and Sasser worms spread very quickly in the days of Windows XP because Windows XP did not come properly secured and exposed system services to the Internet. The worm accessed these system services over the Internet, exploited a vulnerability, and infected the computer. The worm then used the new infected computer to continue replicating itself. Such worms are less common now that Windows is properly firewalled by default, but worms can also spread in other ways — for example, by mass-emailing themselves to every email address in an effected user’s address book. Like a virus, a worm can do any number of other harmful things once it infects a computer. The key thing that makes it a worm is simply how it spreads copies of itself. Trojan (or Trojan Horse) A Trojan horse, or Trojan, is a type of malware that disguises itself as a legitimate file. When you download and run the program, the Trojan horse will run in the background, allowing third-parties to access your computer. Trojans can do this for any number of reasons — to monitor activity on your computer, to join your computer to a botnet. Trojans may also be used to open the floodgates and download many other types of malware onto your computer. The key thing that makes this type of malware a Trojan is how it arrives. It pretends to be a useful program and, when run, it hides in the background and gives malicious people access to your computer. It isn’t obsessed with copying itself into other files or spreading over the network, as viruses and worms are. For example, a piece of pirated software on an unscrupulous website may actually contain a Trojan. Spyware Spyware is a type of malicious software that spies on you without your knowledge. It collects a variety of different types of data, depending on the piece of spyware. Different types of malware can function as spyware — there may be malicious spyware included in Trojans that spies on your keystrokes to steal financial data, for example. More “legitimate” spyware may be bundled along with free software and simply monitor your web browsing habits, uploading this data to advertising servers so the software’s creator can make money from selling their knowledge of your activities. Adware Adware often comes along with spyware. It’s any type of software that displays advertising on your computer. Programs that display advertisements inside the program itself aren’t generally classified as malware. The kind of “adware” that’s particularly malicious is the kind that abuses its access to your system to display ads when it shouldn’t. For example, a piece of harmful adware may cause pop-up advertisements to appear on your computer when you’re not doing anything else. Or, adware may inject additional advertising into other web pages as you browse the web. Adware is often combined with spyware — a piece of malware may monitor your browsing habits and use them to serve you more targeted ads. Adware is more “socially acceptable” than other types of malware on Windows and you may see adware bundled with legitimate programs. For example, some people consider the Ask Toolbar included with Oracle’s Java software adware. Keylogger A keylogger is a type of malware that runs in the background, recording every key stroke you make. These keystrokes can include usernames, passwords, credit card numbers, and other sensitive data. The keylogger then, most likely, uploads these keystrokes to a malicious server, where it can be analyzed and people can pick out the useful passwords and credit card numbers. Other types of malware can act as keyloggers. A virus, worm, or Trojan may function as a keylogger, for example. Keyloggers may also be installed for monitoring purposes by businesses or even jealous spouses. Botnet, Bot A botnet is a large network of computers that are under the botnet creator’s control. Each computer functions as a “bot” because it’s infected with a specific piece of malware. Once the bot software infects the computer, ir will connect to some sort of control server and wait for instructions from the botnet’s creator. For example, a botnet may be used to initiate a DDoS (distributed denial of service) attack. Every computer in the botnet will be told to bombard a specific website or server with requests at once, and such millions or requests can cause a server to become unresponsive or crash. Botnet creators may sell access to their botnets, allowing other malicious individuals to use large botnets to do their dirty work. Rootkit A rootkit is a type of malware designed to burrow deep into your computer, avoiding detection by security programs and users. For example, a rootkit might load before most of Windows, burying itself deep into the system and modifying system functions so that security programs can’t detect it. A rootkit might hide itself completely, preventing itself from showing up in the Windows task manager. The key thing that makes a type of malware a rootkit is that it’s stealthy and focused on hiding itself once it arrives. Ransomware Ransomware is a fairly new type of malware. It holds your computer or files hostage and demands a ransom payment. Some ransomware may simply pop up a box asking for money before you can continue using your computer. Such prompts are easily defeated with antivirus software. More harmful malware like CryptoLocker literally encrypts your files and demands a payment before you can access them. Such types of malware are dangerous, especially if you don’t have backups. Most malware these days is produced for profit, and ransomware is a good example of that. Ransomware doesn’t want to crash your computer and delete your files just to cause you trouble. It wants to take something hostage and get a quick payment from you. So why is it called “antivirus software,” anyway? Well, most people continue to consider the word “virus” synonymous with malware as a whole. Antivirus software doesn’t just protect against viruses, but against all types of malware. It may be more accurately referred to as “antimalware” or “security” software. Image Credit: Marcelo Alves on Flickr, Tama Leaver on Flickr, Szilard Mihaly on Flickr     

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  • OBIEE 11.1.1 - Tips for In-place Upgrade from 11.1.1.6 to 11.1.1.7.x

    - by Ahmed Awan
    Tips: – Use the Test to Production (T2P) / cloning process (movement scripts). For example: – Clone up the existing 11.1.1.6 environment.– Move the cloned copy to the new location / host (same 11.1.1.6.0 version at this point).– Patch new location / host (11.1.1.6) to the 11.1.1.7 level.– Switch to Production. – How to use movement scripts for OBIEE: 20.1 Introduction to the Movement Scripts , for details refer to: http://docs.oracle.com/cd/E29542_01/core.1111/e10105/clone.htm#CACHFECE 21.4.7.1 Moving Oracle Business Intelligence to a New Target Environment, for details refer to: http://docs.oracle.com/cd/E29542_01/core.1111/e10105/testprod.htm#CHDIAEFA http://docs.oracle.com/cd/E29542_01/core.1111/e10105/testprod.htm#BABGJGCF – Perform in-place upgrade to 11.1.1.7.0 using manual steps / Upgrade wizard, refer to: http://docs.oracle.com/cd/E28280_01/upgrade.1111/e16452/bi_plan.htm#BABECJJH

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  • Equivalent of LaTeX's \label and \ref in HTML.

    - by dreeves
    I have an FAQ in HTML (example) in which the questions refer to each other a lot. That means whenever we insert/delete/rearrange the questions, the numbering changes. LaTeX solves this very elegantly with \label and \ref -- you give items simple tags and LaTeX worries about converting to numbers in the final document. How do people deal with that in HTML? ADDED: Note that this is no problem if you don't have to actually refer to items by number, in which case you can set a tag with <a name="foo"> and then link to it with <a href="#foo">some non-numerical way to refer to foo</a>. But I'm assuming "foo" has some auto-generated number, say from an <ol> list, and I want to use that number to refer to and link to it.

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  • Difference between SRC and HREF

    - by Vijey
    The SRC and HREF attributes are used to include some external entities like an image, a CSS file, a html file, any other web page or a javascript file. Is there a clear differentiation between SRC and HREF? where/when to use SRC or HREF? I think they can't be used interchangeably. I'm giving below few examples where these attributes are used: To refer a CSS file: href="cssfile.css" inside the link tag To refer a js file: src="myscript.js" inside the script tag To refer an image file: src="mypic.jpg" inside an image tag To refer another webpage: href="http://www.webpage.com" inside an anchor tag

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  • Why is Internet Explorer the only browser to be referred to by version when talking about compatibility?

    - by Rue Leonheart
    Whenever I read something or hear someone talking about HTML5, CSS and JavaScript support, they always refer to Internet Explorer with the version number such as Internet Explorer 6, and Internet Explorer 9. But they only refer to Google Chrome, Firefox, Safari and others without version numbers. Shouldn't they also specify the version number in which certain web technologies are incompatible for other browsers instead of just Internet Explorer?

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  • Where Twitter Stands Heading Into 2013

    - by Mike Stiles
    As Twitter continued throughout 2012 to be a stage on which global politics and culture played itself out, the company itself underwent some adjustments that give us a good indication of what users and brands can expect from the platform in 2013. The power of the network did anything but fade. Celebrities continued to use it to connect one-on-one. Even the Pope signed on this year. It continued to fuel revolutions. It played an exponentially large factor in this US Presidential election. And around the world, the freedom to speak was challenged as users were fired, sued, sometimes even jailed for their tweets. Expect more of the same in 2013, as Twitter has entrenched itself, for individuals, causes and brands, as the fastest, easiest, most efficient way to message the masses so some measure of impact can come from it. It’s changed everything, and it’s not finished. These fun facts reveal the position of strength with which Twitter enters 2013: It now generates a billion tweets every 2.5 days It has 500 million+ users The average Twitter user has tweeted 307 times 32% of everyone using the Internet uses Twitter It’s expected to bring in $540 million in ad revenue by 2014 11 new accounts are created every second High-level Executive Summary: people love it, people use it, and they’re going to keep loving and using it. Whether or not outside developers love it is a different matter. 2012 marked a shift from welcoming the third party support that played at least some role in Twitter being so warmly embraced, to discouraging anything that replicates what Twitter can do itself…or plans to do itself. It’s not the open playground it once was. Now Twitter must spend 2013 proving it can innovate in-house and keep us just as entranced. Likewise, Twitter is distancing itself from Facebook. Images from the #1 platform’s Instagram don’t work on Twitter anymore, and Twitter’s rolling out their own photo filter product. Where the two have lived in a “plenty of room for everybody” symbiosis up to now, 2013 could see the giants ramping up a full-on rivalry. Twitter is exhibiting a deliberate strategy. Updates have centered on more visually appealing search results, and making finding and sharing content easier. Deals have been cut with some media entities so their content stands out. CEO Dick Costolo has said tweets aren’t the attraction, they’re what leads you to content. Twitter aims to be a key distributor of media and info. Add the addition of former News Corp. President Peter Chernin to the board, and their hashtag landing page experience for events, and their media behemoth ambitions get pretty clear. There are challenges ahead and Costolo has also laid those out; entry into China, figuring out how to have Twitter deliver both comprehensive and relevant, targeted experiences, and the visualization of big data. What does this mean for corporations? They can expect a more media-rich evolution and growing emphases on imagery. They can expect more opportunities to create great media content and leverage Twitter for its distribution. And they can expect new ways to surface in searches. Are brands diving in? 56% of customer tweets to companies get completely and totally ignored. Ugh. A study Twitter recently conducted with Compete shows people who see tweets from retailers are more likely to buy a product. And, the more retailer tweets they see, the more likely they are to purchase on the retail site. As more of those tweets point to engaging media content from the brand, the results should get even better. Twitter appears ready for 2013. Enterprise brands have some work to do. @mikestilesPhoto Stuart Miles, freedigitalphotos.net

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  • What exactly is saved in SQL Server Statistics? When they get updated? Is SQL Server itself is taking care of them?

    - by Pritesh
    I have been working with SQL Server as a Developer a while. One thing I learnt is SQL Server manages Statistics which help Engine to create optimized execution plan. I could not figure out what exactly is stores in Statistics? (I read it saves Vector, but what Vector?) When/In which scenario SQL Server updates Statistics? How/why some time they go out of sync (old Statistics) In case of old Statistics is a manual DBA/Developer intervention is required or SQL Server Will get them updated. As a DBA/Developer how to find out if Statistics OLD? What should we do?

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  • Oracle Solaris 11 ZFS Lab for Openworld 2012

    - by user12626122
    Preface This is the content from the Oracle Openworld 2012 ZFS lab. It was well attended - the feedback was that it was a little short - thats probably because in writing it I bacame very time-concious after the ASM/ACFS on Solaris extravaganza I ran last year which was almost too long for mortal man to finish in the 1 hour session. Enjoy. Table of Contents Exercise Z.1: ZFS Pools Exercise Z.2: ZFS File Systems Exercise Z.3: ZFS Compression Exercise Z.4: ZFS Deduplication Exercise Z.5: ZFS Encryption Exercise Z.6: Solaris 11 Shadow Migration Introduction This set of exercises is designed to briefly demonstrate new features in Solaris 11 ZFS file system: Deduplication, Encryption and Shadow Migration. Also included is the creation of zpools and zfs file systems - the basic building blocks of the technology, and also Compression which is the compliment of Deduplication. The exercises are just introductions - you are referred to the ZFS Adminstration Manual for further information. From Solaris 11 onward the online manual pages consist of zpool(1M) and zfs(1M) with further feature-specific information in zfs_allow(1M), zfs_encrypt(1M) and zfs_share(1M). The lab is easily carried out in a VirtualBox running Solaris 11 with 6 virtual 3 Gb disks to play with. Exercise Z.1: ZFS Pools Task: You have several disks to use for your new file system. Create a new zpool and a file system within it. Lab: You will check the status of existing zpools, create your own pool and expand it. Your Solaris 11 installation already has a root ZFS pool. It contains the root file system. Check this: root@solaris:~# zpool list NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT rpool 15.9G 6.62G 9.25G 41% 1.00x ONLINE - root@solaris:~# zpool status pool: rpool state: ONLINE scan: none requested config: NAME STATE READ WRITE CKSUM rpool ONLINE 0 0 0 c3t0d0s0 ONLINE 0 0 0 errors: No known data errors Note the disk device the root pool is on - c3t0d0s0 Now you will create your own ZFS pool. First you will check what disks are available: root@solaris:~# echo | format Searching for disks...done AVAILABLE DISK SELECTIONS: 0. c3t0d0 <ATA-VBOX HARDDISK-1.0 cyl 2085 alt 2 hd 255 sec 63> /pci@0,0/pci8086,2829@d/disk@0,0 1. c3t2d0 <ATA-VBOX HARDDISK-1.0 cyl 1534 alt 2 hd 128 sec 32> /pci@0,0/pci8086,2829@d/disk@2,0 2. c3t3d0 <ATA-VBOX HARDDISK-1.0 cyl 1534 alt 2 hd 128 sec 32> /pci@0,0/pci8086,2829@d/disk@3,0 3. c3t4d0 <ATA-VBOX HARDDISK-1.0 cyl 1534 alt 2 hd 128 sec 32> /pci@0,0/pci8086,2829@d/disk@4,0 4. c3t5d0 <ATA-VBOX HARDDISK-1.0 cyl 1534 alt 2 hd 128 sec 32> /pci@0,0/pci8086,2829@d/disk@5,0 5. c3t6d0 <ATA-VBOX HARDDISK-1.0 cyl 1534 alt 2 hd 128 sec 32> /pci@0,0/pci8086,2829@d/disk@6,0 6. c3t7d0 <ATA-VBOX HARDDISK-1.0 cyl 1534 alt 2 hd 128 sec 32> /pci@0,0/pci8086,2829@d/disk@7,0 Specify disk (enter its number): Specify disk (enter its number): The root disk is numbered 0. The others are free for use. Try creating a simple pool and observe the error message: root@solaris:~# zpool create mypool c3t2d0 c3t3d0 'mypool' successfully created, but with no redundancy; failure of one device will cause loss of the pool So destroy that pool and create a mirrored pool instead: root@solaris:~# zpool destroy mypool root@solaris:~# zpool create mypool mirror c3t2d0 c3t3d0 root@solaris:~# zpool status mypool pool: mypool state: ONLINE scan: none requested config: NAME STATE READ WRITE CKSUM mypool ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 c3t2d0 ONLINE 0 0 0 c3t3d0 ONLINE 0 0 0 errors: No known data errors Back to topExercise Z.2: ZFS File Systems Task: You have to create file systems for later exercises. You can see that when a pool is created, a file system of the same name is created: root@solaris:~# zfs list NAME USED AVAIL REFER MOUNTPOINT mypool 86.5K 2.94G 31K /mypool Create your filesystems and mountpoints as follows: root@solaris:~# zfs create -o mountpoint=/data1 mypool/mydata1 The -o option sets the mount point and automatically creates the necessary directory. root@solaris:~# zfs list mypool/mydata1 NAME USED AVAIL REFER MOUNTPOINT mypool/mydata1 31K 2.94G 31K /data1 Back to top Exercise Z.3: ZFS Compression Task:Try out different forms of compression available in ZFS Lab:Create 2nd filesystem with compression, fill both file systems with the same data, observe results You can see from the zfs(1) manual page that there are several types of compression available to you, set with the property=value syntax: compression=on | off | lzjb | gzip | gzip-N | zle Controls the compression algorithm used for this dataset. The lzjb compression algorithm is optimized for performance while providing decent data compression. Setting compression to on uses the lzjb compression algorithm. The gzip compression algorithm uses the same compression as the gzip(1) command. You can specify the gzip level by using the value gzip-N where N is an integer from 1 (fastest) to 9 (best compression ratio). Currently, gzip is equivalent to gzip-6 (which is also the default for gzip(1)). Create a second filesystem with compression turned on. Note how you set and get your values separately: root@solaris:~# zfs create -o mountpoint=/data2 mypool/mydata2 root@solaris:~# zfs set compression=gzip-9 mypool/mydata2 root@solaris:~# zfs get compression mypool/mydata1 NAME PROPERTY VALUE SOURCE mypool/mydata1 compression off default root@solaris:~# zfs get compression mypool/mydata2 NAME PROPERTY VALUE SOURCE mypool/mydata2 compression gzip-9 local Now you can copy the contents of /usr/lib into both your normal and compressing filesystem and observe the results. Don't forget the dot or period (".") in the find(1) command below: root@solaris:~# cd /usr/lib root@solaris:/usr/lib# find . -print | cpio -pdv /data1 root@solaris:/usr/lib# find . -print | cpio -pdv /data2 The copy into the compressing file system takes longer - as it has to perform the compression but the results show the effect: root@solaris:/usr/lib# zfs list NAME USED AVAIL REFER MOUNTPOINT mypool 1.35G 1.59G 31K /mypool mypool/mydata1 1.01G 1.59G 1.01G /data1 mypool/mydata2 341M 1.59G 341M /data2 Note that the available space in the pool is shared amongst the file systems. This behavior can be modified using quotas and reservations which are not covered in this lab but are covered extensively in the ZFS Administrators Guide. Back to top Exercise Z.4: ZFS Deduplication The deduplication property is used to remove redundant data from a ZFS file system. With the property enabled duplicate data blocks are removed synchronously. The result is that only unique data is stored and common componenents are shared. Task:See how to implement deduplication and its effects Lab: You will create a ZFS file system with deduplication turned on and see if it reduces the amount of physical storage needed when we again fill it with a copy of /usr/lib. root@solaris:/usr/lib# zfs destroy mypool/mydata2 root@solaris:/usr/lib# zfs set dedup=on mypool/mydata1 root@solaris:/usr/lib# rm -rf /data1/* root@solaris:/usr/lib# mkdir /data1/2nd-copy root@solaris:/usr/lib# zfs list NAME USED AVAIL REFER MOUNTPOINT mypool 1.02M 2.94G 31K /mypool mypool/mydata1 43K 2.94G 43K /data1 root@solaris:/usr/lib# find . -print | cpio -pd /data1 2142768 blocks root@solaris:/usr/lib# zfs list NAME USED AVAIL REFER MOUNTPOINT mypool 1.02G 1.99G 31K /mypool mypool/mydata1 1.01G 1.99G 1.01G /data1 root@solaris:/usr/lib# find . -print | cpio -pd /data1/2nd-copy 2142768 blocks root@solaris:/usr/lib#zfs list NAME USED AVAIL REFER MOUNTPOINT mypool 1.99G 1.96G 31K /mypool mypool/mydata1 1.98G 1.96G 1.98G /data1 You could go on creating copies for quite a while...but you get the idea. Note that deduplication and compression can be combined: the compression acts on metadata. Deduplication works across file systems in a pool and there is a zpool-wide property dedupratio: root@solaris:/usr/lib# zpool get dedupratio mypool NAME PROPERTY VALUE SOURCE mypool dedupratio 4.30x - Deduplication can also be checked using "zpool list": root@solaris:/usr/lib# zpool list NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT mypool 2.98G 1001M 2.01G 32% 4.30x ONLINE - rpool 15.9G 6.66G 9.21G 41% 1.00x ONLINE - Before moving on to the next topic, destroy that dataset and free up some space: root@solaris:~# zfs destroy mypool/mydata1 Back to top Exercise Z.5: ZFS Encryption Task: Encrypt sensitive data. Lab: Explore basic ZFS encryption. This lab only covers the basics of ZFS Encryption. In particular it does not cover various aspects of key management. Please see the ZFS Adminastrion Manual and the zfs_encrypt(1M) manual page for more detail on this functionality. Back to top root@solaris:~# zfs create -o encryption=on mypool/data2 Enter passphrase for 'mypool/data2': ******** Enter again: ******** root@solaris:~# Creation of a descendent dataset shows that encryption is inherited from the parent: root@solaris:~# zfs create mypool/data2/data3 root@solaris:~# zfs get -r encryption,keysource,keystatus,checksum mypool/data2 NAME PROPERTY VALUE SOURCE mypool/data2 encryption on local mypool/data2 keysource passphrase,prompt local mypool/data2 keystatus available - mypool/data2 checksum sha256-mac local mypool/data2/data3 encryption on inherited from mypool/data2 mypool/data2/data3 keysource passphrase,prompt inherited from mypool/data2 mypool/data2/data3 keystatus available - mypool/data2/data3 checksum sha256-mac inherited from mypool/data2 You will find the online manual page zfs_encrypt(1M) contains examples. In particular, if time permits during this lab session you may wish to explore the changing of a key using "zfs key -c mypool/data2". Exercise Z.6: Shadow Migration Shadow Migration allows you to migrate data from an old file system to a new file system while simultaneously allowing access and modification to the new file system during the process. You can use Shadow Migration to migrate a local or remote UFS or ZFS file system to a local file system. Task: You wish to migrate data from one file system (UFS, ZFS, VxFS) to ZFS while mainaining access to it. Lab: Create the infrastructure for shadow migration and transfer one file system into another. First create the file system you want to migrate root@solaris:~# zpool create oldstuff c3t4d0 root@solaris:~# zfs create oldstuff/forgotten Then populate it with some files: root@solaris:~# cd /var/adm root@solaris:/var/adm# find . -print | cpio -pdv /oldstuff/forgotten You need the shadow-migration package installed: root@solaris:~# pkg install shadow-migration Packages to install: 1 Create boot environment: No Create backup boot environment: No Services to change: 1 DOWNLOAD PKGS FILES XFER (MB) Completed 1/1 14/14 0.2/0.2 PHASE ACTIONS Install Phase 39/39 PHASE ITEMS Package State Update Phase 1/1 Image State Update Phase 2/2 You then enable the shadowd service: root@solaris:~# svcadm enable shadowd root@solaris:~# svcs shadowd STATE STIME FMRI online 7:16:09 svc:/system/filesystem/shadowd:default Set the filesystem to be migrated to read-only root@solaris:~# zfs set readonly=on oldstuff/forgotten Create a new zfs file system with the shadow property set to the file system to be migrated: root@solaris:~# zfs create -o shadow=file:///oldstuff/forgotten mypool/remembered Use the shadowstat(1M) command to see the progress of the migration: root@solaris:~# shadowstat EST BYTES BYTES ELAPSED DATASET XFRD LEFT ERRORS TIME mypool/remembered 92.5M - - 00:00:59 mypool/remembered 99.1M 302M - 00:01:09 mypool/remembered 109M 260M - 00:01:19 mypool/remembered 133M 304M - 00:01:29 mypool/remembered 149M 339M - 00:01:39 mypool/remembered 156M 86.4M - 00:01:49 mypool/remembered 156M 8E 29 (completed) Note that if you had created /mypool/remembered as encrypted, this would be the preferred method of encrypting existing data. Similarly for compressing or deduplicating existing data. The procedure for migrating a file system over NFS is similar - see the ZFS Administration manual. That concludes this lab session.

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