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  • my 4 month old 500 GB SATA HDD making noise

    - by Jitendra vyas
    my 4 month old 500 GB SATA HDD making noise, somrtime and pc hangs when it make noise when noise is over then desktop work fine. it's not happens daily but it happens. IS something wrong with HDD, or Data, power cable, or my Cabinet's power supply. should i run scandisk, defragmentation to whole disk.

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  • Troubleshooting painfully slow Windows XP boot

    - by shan
    When I reboot my machine, it takes around 10-15 minutes to boot. Tried removing unused programs, disk defragmentation, check disk, but I'm not able to identify the issue. Any ideas to troubleshoot to see whether there is any failure, trying to start a service/program?

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  • Linux filesystem with inodes close on the disk

    - by pts
    I'd like to make the ls -laR /media/myfs on Linux as fast as possible. I'll have 1 million files on the filesystem, 2TB of total file size, and some directories containing as much as 10000 files. Which filesystem should I use and how should I configure it? As far as I understand, the reason why ls -laR is slow because it has to stat(2) each inode (i.e. 1 million stat(2)s), and since inodes are distributed randomly on the disk, each stat(2) needs one disk seek. Here are some solutions I had in mind, none of which I am satisfied with: Create the filesystem on an SSD, because the seek operations on SSDs are fast. This wouldn't work, because a 2TB SSD doesn't exist, or it's prohibitively expensive. Create a filesystem which spans on two block devices: an SSD and a disk; the disk contains file data, and the SSD contains all the metadata (including directory entries, inodes and POSIX extended attributes). Is there a filesystem which supports this? Would it survive a system crash (power outage)? Use find /media/myfs on ext2, ext3 or ext4, instead of ls -laR /media/myfs, because the former can the advantage of the d_type field (see in the getdents(2) man page), so it doesn't have to stat. Unfortunately, this doesn't meet my requirements, because I need all file sizes as well, which find /media/myfs doesn't print. Use a filesystem, such as VFAT, which stores inodes in the directory entries. I'd love this one, but VFAT is not reliable and flexible enough for me, and I don't know of any other filesystem which does that. Do you? Of course, storing inodes in the directory entries wouldn't work for files with a link count more than 1, but that's not a problem since I have only a few dozen such files in my use case. Adjust some settings in /proc or sysctl so that inodes are locked to system memory forever. This would not speed up the first ls -laR /media/myfs, but it would make all subsequent invocations amazingly fast. How can I do this? I don't like this idea, because it doesn't speed up the first invocation, which currently takes 30 minutes. Also I'd like to lock the POSIX extended attributes in memory as well. What do I have to do for that? Use a filesystem which has an online defragmentation tool, which can be instructed to relocate inodes to the the beginning of the block device. Once the relocation is done, I can run dd if=/dev/sdb of=/dev/null bs=1M count=256 to get the beginning of the block device fetched to the kernel in-memory cache without seeking, and then the stat(2) operations would be fast, because they read from the cache. Is there a way to lock those inodes and/or blocks into memory once they have been read? Which filesystem has such a defragmentation tool?

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  • 4 month old 500 GB SATA HDD making noise?

    - by metal gear solid
    My 4 month old 500 GB SATA HDD making noise sometimes and the PC hangs when it makes noise when the noise stops desktop work fine. It doesn't happen every day but it does happen. Is something wrong with HDD, Data, power cable, or my cabinet's power supply? Should I run scandisk or defragmentation on the disk.

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  • Windows7: Gaining administrator rights in CLI without being prompted for password

    - by liori
    Hello, I am trying to write a script which includes disk defragmentation as one of its steps. defrag needs administrative rights to work. I tried to use runas /user:Administrator, but it always asked me for password (even though there isn't one set). The script needs to run unattended for a long time, and it needs to be started from standard user account (it is actually being run by cygwin), so I'd like to get rid of that prompt. Is this possible? Thanks,

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  • How does ecryptfs impact harddisk performance?

    - by Freddi
    I have my home directy encrypted with ecryptfs. Does ecryptfs lead to fragmentation? I have the feeling that reading files, displaying folders and login became continuously slower and slower (although it was not noticeably slow at the beginning). The hard disk makes a lot of seek noise even if I open only a text file. In /home/.ecryptfs I see many big archives (that probably contain the encrypted files), so I'm wondering if Linux file system online defragmentation gains anything here. What options do I have to increase performance? Should I decide whether I maybe better do without encryption?

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  • What Is Disk Fragmentation and Do I Still Need to Defragment?

    - by Jason Fitzpatrick
    Do modern computers still need the kind of routine defragmentation procedures that older computers called for? Read on to learn about fragmentation and what modern operating systems and file systems do to minimize performance impacts. Today’s Question & Answer session comes to us courtesy of SuperUser—a subdivision of Stack Exchange, a community-drive grouping of Q&A web sites. Secure Yourself by Using Two-Step Verification on These 16 Web Services How to Fix a Stuck Pixel on an LCD Monitor How to Factory Reset Your Android Phone or Tablet When It Won’t Boot

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  • Is there a scheduling algorithm that optimizes for "maker's schedules"?

    - by John Feminella
    You may be familiar with Paul Graham's essay, "Maker's Schedule, Manager's Schedule". The crux of the essay is that for creative and technical professionals, meetings are anathema to productivity, because they tend to lead to "schedule fragmentation", breaking up free time into chunks that are too small to acquire the focus needed to solve difficult problems. In my firm we've seen significant benefits by minimizing the amount of disruption caused, but the brute-force algorithm we use to decide schedules is not sophisticated enough to handle scheduling large groups of people well. (*) What I'm looking for is if there's are any well-known algorithms which minimize this productivity disruption, among a group of N makers and managers. In our model, There are N people. Each person pi is either a maker (Mk) or a manager (Mg). Each person has a schedule si. Everyone's schedule is H hours long. A schedule consists of a series of non-overlapping intervals si = [h1, ..., hj]. An interval is either free or busy. Two adjacent free intervals are equivalent to a single free interval that spans both. A maker's productivity is maximized when the number of free intervals is minimized. A manager's productivity is maximized when the total length of free intervals is maximized. Notice that if there are no meetings, both the makers and the managers experience optimum productivity. If meetings must be scheduled, then makers prefer that meetings happen back-to-back, while managers don't care where the meeting goes. Note that because all disruptions are treated as equally harmful to makers, there's no difference between a meeting that lasts 1 second and a meeting that lasts 3 hours if it segments the available free time. The problem is to decide how to schedule M different meetings involving arbitrary numbers of the N people, where each person in a given meeting must place a busy interval into their schedule such that it doesn't overlap with any other busy interval. For each meeting Mt the start time for the busy interval must be the same for all parties. Does an algorithm exist to solve this problem or one similar to it? My first thought was that this looks really similar to defragmentation (minimize number of distinct chunks), and there are a lot of algorithms about that. But defragmentation doesn't have much to do with scheduling. Thoughts? (*) Practically speaking this is not really a problem, because it's rare that we have meetings with more than ~5 people at once, so the space of possibilities is small.

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  • Defragmenting the registry

    - by team-ferrari22
    Hi All, Does any body know how to defragment windows registry. We googled and found several free tools doing the same.But no tool is having open source. One tool is there - 'UltraDefrag' which is open source tool written in 'C' for file defragmentation. Please provide help in searching open source/ sample code to defragment windows registry...or any windows API functions or libraries for doing the same. Regards.

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  • A space-efficient guest filesystem for grow-as-needed virtual disks ?

    - by Steve Schnepp
    A common practice is to use non-preallocated virtual disks. Since they only grow as needed, it makes them perfect for fast backup, overallocation and creation speed. Since file systems are usually based on physical disks they have the tendency to use the whole area available1 in order to increase the speed2 or reliability3. I'm searching a filesystem that does the exact opposite : try to touch the minimum blocks need by an aggressive block reuse. I would happily trade some performance for space usage. There is already a similar question, but it is rather general. I have very specific goal : space-efficiency. 1. Like page caching uses all the free physical memory 2. Canonical example : online defragmentation 3. Canonical example : snapshotting

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  • Why can't I defragment my SQL 2008 .mdf file?

    - by LesterDove
    I am defragmenting a badly (95%) fragmented drive upon which large (35 gig) SQL Server 2008 .mdf files live. After defragmenting and viewing the exception report, I see that the production .mdf file that I'm most interested in could not be defragmented. I initially figured it was because MSSQL had an exclusive lock on the file, so I detached it and tried again. No luck - this particular .mdf file could not be defragmented. What am I missing? Most online references suggest that I should be able to file defrag an .mdf A note: yes, I'm talking about file defragmentation, not index defrag, which is already being done routinely, and which I'll re-run after this. Thanks! What am I missing?

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  • A space-efficient filesystem for grow-as-needed virtual disks ?

    - by Steve Schnepp
    A common practice is to use non-preallocated virtual disks. Since they only grow as needed, it makes them perfect for fast backup, overallocation and creation speed. Since file systems are usually based on physical disks they have the tendency to use the whole area available1 in order to increase the speed2 or reliability3. I'm searching a filesystem that does the exact opposite : try to touch the minimum blocks need by an aggressive block reuse. I would happily trade some performance for space usage. There is already a similar question, but it is rather general. I have very specific goal : space-efficiency. 1. Like page caching uses all the free physical memory 2. Canonical example : online defragmentation 3. Canonical example : snapshotting

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  • quick look at: dm_db_index_physical_stats

    - by fatherjack
    A quick look at the key data from this dmv that can help a DBA keep databases performing well and systems online as the users need them. When the dynamic management views relating to index statistics became available in SQL Server 2005 there was much hype about how they can help a DBA keep their servers running in better health than ever before. This particular view gives an insight into the physical health of the indexes present in a database. Whether they are use or unused, complete or missing some columns is irrelevant, this is simply the physical stats of all indexes; disabled indexes are ignored however. In it’s simplest form this dmv can be executed as:   The results from executing this contain a record for every index in every database but some of the columns will be NULL. The first parameter is there so that you can specify which database you want to gather index details on, rather than scan every database. Simply specifying DB_ID() in place of the first NULL achieves this. In order to avoid the NULLS, or more accurately, in order to choose when to have the NULLS you need to specify a value for the last parameter. It takes one of 4 values – DEFAULT, ‘SAMPLED’, ‘LIMITED’ or ‘DETAILED’. If you execute the dmv with each of these values you can see some interesting details in the times taken to complete each step. DECLARE @Start DATETIME DECLARE @First DATETIME DECLARE @Second DATETIME DECLARE @Third DATETIME DECLARE @Finish DATETIME SET @Start = GETDATE() SELECT * FROM [sys].[dm_db_index_physical_stats](DB_ID(), NULL, NULL, NULL, DEFAULT) AS ddips SET @First = GETDATE() SELECT * FROM [sys].[dm_db_index_physical_stats](DB_ID(), NULL, NULL, NULL, 'SAMPLED') AS ddips SET @Second = GETDATE() SELECT * FROM [sys].[dm_db_index_physical_stats](DB_ID(), NULL, NULL, NULL, 'LIMITED') AS ddips SET @Third = GETDATE() SELECT * FROM [sys].[dm_db_index_physical_stats](DB_ID(), NULL, NULL, NULL, 'DETAILED') AS ddips SET @Finish = GETDATE() SELECT DATEDIFF(ms, @Start, @First) AS [DEFAULT] , DATEDIFF(ms, @First, @Second) AS [SAMPLED] , DATEDIFF(ms, @Second, @Third) AS [LIMITED] , DATEDIFF(ms, @Third, @Finish) AS [DETAILED] Running this code will give you 4 result sets; DEFAULT will have 12 columns full of data and then NULLS in the remainder. SAMPLED will have 21 columns full of data. LIMITED will have 12 columns of data and the NULLS in the remainder. DETAILED will have 21 columns full of data. So, from this we can deduce that the DEFAULT value (the same one that is also applied when you query the view using a NULL parameter) is the same as using LIMITED. Viewing the final result set has some details that are worth noting: Running queries against this view takes significantly longer when using the SAMPLED and DETAILED values in the last parameter. The duration of the query is directly related to the size of the database you are working in so be careful running this on big databases unless you have tried it on a test server first. Let’s look at the data we get back with the DEFAULT value first of all and then progress to the extra information later. We know that the first parameter that we supply has to be a database id and for the purposes of this blog we will be providing that value with the DB_ID function. We could just as easily put a fixed value in there or a function such as DB_ID (‘AnyDatabaseName’). The first columns we get back are database_id and object_id. These are pretty explanatory and we can wrap those in some code to make things a little easier to read: SELECT DB_NAME([ddips].[database_id]) AS [DatabaseName] , OBJECT_NAME([ddips].[object_id]) AS [TableName] … FROM [sys].[dm_db_index_physical_stats](DB_ID(), NULL, NULL, NULL, NULL) AS ddips  gives us   SELECT DB_NAME([ddips].[database_id]) AS [DatabaseName] , OBJECT_NAME([ddips].[object_id]) AS [TableName], [i].[name] AS [IndexName] , ….. FROM [sys].[dm_db_index_physical_stats](DB_ID(), NULL, NULL, NULL, NULL) AS ddips INNER JOIN [sys].[indexes] AS i ON [ddips].[index_id] = [i].[index_id] AND [ddips].[object_id] = [i].[object_id]     These handily tie in with the next parameters in the query on the dmv. If you specify an object_id and an index_id in these then you get results limited to either the table or the specific index. Once again we can place a  function in here to make it easier to work with a specific table. eg. SELECT * FROM [sys].[dm_db_index_physical_stats] (DB_ID(), OBJECT_ID(‘AdventureWorks2008.Person.Address’) , 1, NULL, NULL) AS ddips   Note: Despite me showing that functions can be placed directly in the parameters for this dmv, best practice recommends that functions are not used directly in the function as it is possible that they will fail to return a valid object ID. To be certain of not passing invalid values to this function, and therefore setting an automated process off on the wrong path, declare variables for the OBJECT_IDs and once they have been validated, use them in the function: DECLARE @db_id SMALLINT; DECLARE @object_id INT; SET @db_id = DB_ID(N’AdventureWorks_2008′); SET @object_id = OBJECT_ID(N’AdventureWorks_2008.Person.Address’); IF @db_id IS NULL BEGINPRINT N’Invalid database’; ENDELSE IF @object_id IS NULL BEGINPRINT N’Invalid object’; ENDELSE BEGINSELECT * FROM sys.dm_db_index_physical_stats (@db_id, @object_id, NULL, NULL , ‘LIMITED’); END; GO In cases where the results of querying this dmv don’t have any effect on other processes (i.e. simply viewing the results in the SSMS results area)  then it will be noticed when the results are not consistent with the expected results and in the case of this blog this is the method I have used. So, now we can relate the values in these columns to something that we recognise in the database lets see what those other values in the dmv are all about. The next columns are: We’ll skip partition_number, index_type_desc, alloc_unit_type_desc, index_depth and index_level  as this is a quick look at the dmv and they are pretty self explanatory. The final columns revealed by querying this view in the DEFAULT mode are avg_fragmentation_in_percent. This is the amount that the index is logically fragmented. It will show NULL when the dmv is queried in SAMPLED mode. fragment_count. The number of pieces that the index is broken into. It will show NULL when the dmv is queried in SAMPLED mode. avg_fragment_size_in_pages. The average size, in pages, of a single fragment in the leaf level of the IN_ROW_DATA allocation unit. It will show NULL when the dmv is queried in SAMPLED mode. page_count. Total number of index or data pages in use. OK, so what does this give us? Well, there is an obvious correlation between fragment_count, page_count and avg_fragment_size-in_pages. We see that an index that takes up 27 pages and is in 3 fragments has an average fragment size of 9 pages (27/3=9). This means that for this index there are 3 separate places on the hard disk that SQL Server needs to locate and access to gather the data when it is requested by a DML query. If this index was bigger than 72KB then having it’s data in 3 pieces might not be too big an issue as each piece would have a significant piece of data to read and the speed of access would not be too poor. If the number of fragments increases then obviously the amount of data in each piece decreases and that means the amount of work for the disks to do in order to retrieve the data to satisfy the query increases and this would start to decrease performance. This information can be useful to keep in mind when considering the value in the avg_fragmentation_in_percent column. This is arrived at by an internal algorithm that gives a value to the logical fragmentation of the index taking into account the multiple files, type of allocation unit and the previously mentioned characteristics if index size (page_count) and fragment_count. Seeing an index with a high avg_fragmentation_in_percent value will be a call to action for a DBA that is investigating performance issues. It is possible that tables will have indexes that suffer from rapid increases in fragmentation as part of normal daily business and that regular defragmentation work will be needed to keep it in good order. In other cases indexes will rarely become fragmented and therefore not need rebuilding from one end of the year to another. Keeping this in mind DBAs need to use an ‘intelligent’ process that assesses key characteristics of an index and decides on the best, if any, defragmentation method to apply should be used. There is a simple example of this in the sample code found in the Books OnLine content for this dmv, in example D. There are also a couple of very popular solutions created by SQL Server MVPs Michelle Ufford and Ola Hallengren which I would wholly recommend that you review for much further detail on how to care for your SQL Server indexes. Right, let’s get back on track then. Querying the dmv with the fifth parameter value as ‘DETAILED’ takes longer because it goes through the index and refreshes all data from every level of the index. As this blog is only a quick look a we are going to skate right past ghost_record_count and version_ghost_record_count and discuss avg_page_space_used_in_percent, record_count, min_record_size_in_bytes, max_record_size_in_bytes and avg_record_size_in_bytes. We can see from the details below that there is a correlation between the columns marked. Column 1 (Page_Count) is the number of 8KB pages used by the index, column 2 is how full each page is (how much of the 8KB has actual data written on it), column 3 is how many records are recorded in the index and column 4 is the average size of each record. This approximates to: ((Col1*8) * 1024*(Col2/100))/Col3 = Col4*. avg_page_space_used_in_percent is an important column to review as this indicates how much of the disk that has been given over to the storage of the index actually has data on it. This value is affected by the value given for the FILL_FACTOR parameter when creating an index. avg_record_size_in_bytes is important as you can use it to get an idea of how many records are in each page and therefore in each fragment, thus reinforcing how important it is to keep fragmentation under control. min_record_size_in_bytes and max_record_size_in_bytes are exactly as their names set them out to be. A detail of the smallest and largest records in the index. Purely offered as a guide to the DBA to better understand the storage practices taking place. So, keeping an eye on avg_fragmentation_in_percent will ensure that your indexes are helping data access processes take place as efficiently as possible. Where fragmentation recurs frequently then potentially the DBA should consider; the fill_factor of the index in order to leave space at the leaf level so that new records can be inserted without causing fragmentation so rapidly. the columns used in the index should be analysed to avoid new records needing to be inserted in the middle of the index but rather always be added to the end. * – it’s approximate as there are many factors associated with things like the type of data and other database settings that affect this slightly.  Another great resource for working with SQL Server DMVs is Performance Tuning with SQL Server Dynamic Management Views by Louis Davidson and Tim Ford – a free ebook or paperback from Simple Talk. Disclaimer – Jonathan is a Friend of Red Gate and as such, whenever they are discussed, will have a generally positive disposition towards Red Gate tools. Other tools are often available and you should always try others before you come back and buy the Red Gate ones. All code in this blog is provided “as is” and no guarantee, warranty or accuracy is applicable or inferred, run the code on a test server and be sure to understand it before you run it on a server that means a lot to you or your manager.

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  • btrfs and missing free space

    - by easteregg
    I converted my ext4 partition to btrfs and deleted the save subvolume after doing so. Then I enabled the compression (lzo) of the filessystem in the fstab file and everything is correct so far. Then I forced the compression of all files using the defragmentation command with the parameter -c that the new compression is applied to all files. While doing so, I noticed that my ssd got completly filled up - before I had 6gigs of free space. No I got nothing left. easteregg@x201s:~$ btrfs fi df / Data: total=50.00GB, used=49.17GB System: total=32.00MB, used=4.00KB Metadata: total=24.50GB, used=9.86GB and easteregg@x201s:~$ df -ha Filesystem Size Used Avail Use% Mounted on /dev/sda1 75G 60G 852M 99% / So now. How can I regain my free space. I expected to gain more space because of the lzo compression. And now! The fs is correctly mounted. easteregg@x201s:~$ mount /dev/sda1 on / type btrfs (rw,noatime,ssd,compress=lzo) Any ideas how to fix this issue?

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  • SQL Server – Learning SQL Server Performance: Indexing Basics – Video

    - by pinaldave
    Today I remember one of my older cartoon years ago created for Indexing and Performance. Every single time when Performance is discussed, Indexes are mentioned along with it. In recent times, data and application complexity is continuously growing.  The demand for faster query response, performance, and scalability by organizations is increasing and developers and DBAs need to now write efficient code to achieve this. DBA and Developers A DBA’s role is critical, because a production environment has to run 24×7, hence maintenance, trouble shooting, and quick resolutions are the need of the hour.  The first baby step into any performance tuning exercise in SQL Server involves creating, analysing, and maintaining indexes. Though we have learnt indexing concepts from our college days, indexing implementation inside SQL Server can vary.  Understanding this behaviour and designing our applications appropriately will make sure the application is performed to its highest potential. Video Learning Vinod Kumar and myself we often thought about this and realized that practical understanding of the indexes is very important. One can not master every single aspects of the index. However there are some minimum expertise one should gain if performance is one of the concern. We decided to build a course which just addresses the practical aspects of the performance. In this course, we explored some of these indexing fundamentals and we elaborated on how SQL Server goes about using indexes.  At the end of this course of you will know the basic structure of indexes, practical insights into implementation, and maintenance tips and tricks revolving around indexes.  Finally, we will introduce SQL Server 2012 column store indexes.  We have refrained from discussing internal storage structure of the indexes but have taken a more practical, demo-oriented approach to explain these core concepts. Course Outline Here are salient topics of the course. We have explained every single concept along with a practical demonstration. Additionally shared our personal scripts along with the same. Introduction Fundamentals of Indexing Index Fundamentals Index Fundamentals – Visual Representation Practical Indexing Implementation Techniques Primary Key Over Indexing Duplicate Index Clustered Index Unique Index Included Columns Filtered Index Disabled Index Index Maintenance and Defragmentation Introduction to Columnstore Index Indexing Practical Performance Tips and Tricks Index and Page Types Index and Non Deterministic Columns Index and SET Values Importance of Clustered Index Effect of Compression and Fillfactor Index and Functions Dynamic Management Views (DMV) – Fillfactor Table Scan, Index Scan and Index Seek Index and Order of Columns Final Checklist: Index and Performance Well, we believe we have done our part, now waiting for your comments and feedback. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Index, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology, Video

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  • A tiered approach to cloning linux partitons

    - by Djurdjura
    I'm looking at a strategy for cloning Linux (root) partitions without having to use a Live CD. Literature suggests rightly that the source and target partitions must be umounted to be able to get a clean clone. This assumes that you need to use a LiveCD. I was wondering if instead of requiring a LiveCD, if using a 3rd partition that would emulate the LiveCD functionality, if we can't achieve the same functionality. In other words, at a high level a system with 3 partitions (all bootable): Rescue Partition (LiveCD emulation) Running Partition (Source) Backup Partition (Destination) All 3 partitions are LVMS. When it's time to clone the source partition to the backup (destination) partition, we would boot to the rescue partition, unmount the other 2 partitions (is it required?), run disk check on the source, copy to the destination (dd or simple copy to avoid replicating the defragmentation from the source), run disk check on the destination partition, update Grub menu list to force boot from either partition, and reboot into that partition. My question, is it an approach that you'd recommend? MBR in all this? Any gotchas or extra checks required? Thanks, D. PS. On recommendation from members, posting here instead of stackoverflow.com.

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  • BYOD is not a fashion statement; it’s an architectural shift - by Indus Khaitan

    - by Greg Jensen
    Ten years ago, if you asked a CIO, “how mobile is your enterprise?”. The answer would be, “100%, we give Blackberry to all our employees.”Few things have changed since then: 1.    Smartphone form-factors have matured, especially after the launch of iPhone. 2.    Rapid growth of productivity applications and services that enable creation and consumption of digital content 3.    Pervasive mobile data connectivityThere are two threads emerging from the change. Users are rapidly mingling their personas of an individual as well as an employee. In the first second, posting a picture of a fancy dinner on Facebook, to creating an expense report for the same meal on the mobile device. Irrespective of the dual persona, a user’s personal and corporate lives intermingle freely on a single hardware and more often than not, it’s an employees personal smartphone being used for everything. A BYOD program enables IT to “control” an employee owned device, while enabling productivity. More often than not the objective of BYOD programs are financial; instead of the organization, an employee pays for it.  More than a fancy device, BYOD initiatives have become sort of fashion statement, of corporate productivity, of letting employees be in-charge and a show of corporate empathy to not force an archaic form-factor in a world of new device launches every month. BYOD is no longer a means of effectively moving expense dollars and support costs. It does not matter who owns the device, it has to be protected.  BYOD brings an architectural shift.  BYOD is an architecture, which assumes that every device is vulnerable, not just what your employees have brought but what organizations have purchased for their employees. It's an architecture, which forces us to rethink how to provide productivity without comprising security.Why assume that every device is vulnerable? Mobile operating systems are rapidly evolving with leading upgrade announcement every other month. It is impossible for IT to catch-up. More than that, user’s are savvier than earlier.  While IT could install locks at the doors to prevent intruders, it may degrade productivity—which incentivizes user’s to bypass restrictions. A rapidly evolving mobile ecosystem have moving parts which are vulnerable. Hence, creating a mobile security platform, which uses the fundamental blocks of BYOD architecture such as identity defragmentation, IT control and data isolation, ensures that the sprawl of corporate data is contained. In the next post, we’ll dig deeper into the BYOD architecture. Normal 0 false false false EN-US JA X-NONE /* 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-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:12.0pt; font-family:"Cambria","serif"; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin;}

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  • SQL Table stored as a Heap - the dangers within

    - by MikeD
    Nearly all of the time I create a table, I include a primary key, and often that PK is implemented as a clustered index. Those two don't always have to go together, but in my world they almost always do. On a recent project, I was working on a data warehouse and a set of SSIS packages to import data from an OLTP database into my data warehouse. The data I was importing from the business database into the warehouse was mostly new rows, sometimes updates to existing rows, and sometimes deletes. I decided to use the MERGE statement to implement the insert, update or delete in the data warehouse, I found it quite performant to have a stored procedure that extracted all the new, updated, and deleted rows from the source database and dump it into a working table in my data warehouse, then run a stored proc in the warehouse that was the MERGE statement that took the rows from the working table and updated the real fact table. Use Warehouse CREATE TABLE Integration.MergePolicy (PolicyId int, PolicyTypeKey int, Premium money, Deductible money, EffectiveDate date, Operation varchar(5)) CREATE TABLE fact.Policy (PolicyKey int identity primary key, PolicyId int, PolicyTypeKey int, Premium money, Deductible money, EffectiveDate date) CREATE PROC Integration.MergePolicy as begin begin tran Merge fact.Policy as tgtUsing Integration.MergePolicy as SrcOn (tgt.PolicyId = Src.PolicyId) When not matched by Target then Insert (PolicyId, PolicyTypeKey, Premium, Deductible, EffectiveDate)values (src.PolicyId, src.PolicyTypeKey, src.Premium, src.Deductible, src.EffectiveDate) When matched and src.Operation = 'U' then Update set PolicyTypeKey = src.PolicyTypeKey,Premium = src.Premium,Deductible = src.Deductible,EffectiveDate = src.EffectiveDate When matched and src.Operation = 'D' then Delete ;delete from Integration.WorkPolicy commit end Notice that my worktable (Integration.MergePolicy) doesn't have any primary key or clustered index. I didn't think this would be a problem, since it was relatively small table and was empty after each time I ran the stored proc. For one of the work tables, during the initial loads of the warehouse, it was getting about 1.5 million rows inserted, processed, then deleted. Also, because of a bug in the extraction process, the same 1.5 million rows (plus a few hundred more each time) was getting inserted, processed, and deleted. This was being sone on a fairly hefty server that was otherwise unused, and no one was paying any attention to the time it was taking. This week I received a backup of this database and loaded it on my laptop to troubleshoot the problem, and of course it took a good ten minutes or more to run the process. However, what seemed strange to me was that after I fixed the problem and happened to run the merge sproc when the work table was completely empty, it still took almost ten minutes to complete. I immediately looked back at the MERGE statement to see if I had some sort of outer join that meant it would be scanning the target table (which had about 2 million rows in it), then turned on the execution plan output to see what was happening under the hood. Running the stored procedure again took a long time, and the plan output didn't show me much - 55% on the MERGE statement, and 45% on the DELETE statement, and table scans on the work table in both places. I was surprised at the relative cost of the DELETE statement, because there were really 0 rows to delete, but I was expecting to see the table scans. (I was beginning now to suspect that my problem was because the work table was being stored as a heap.) Then I turned on STATS_IO and ran the sproc again. The output was quite interesting.Table 'Worktable'. Scan count 0, logical reads 0, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.Table 'Policy'. Scan count 0, logical reads 0, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.Table 'MergePolicy'. Scan count 1, logical reads 433276, physical reads 60, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0. I've reproduced the above from memory, the details aren't exact, but the essential bit was the very high number of logical reads on the table stored as a heap. Even just doing a SELECT Count(*) from Integration.MergePolicy incurred that sort of output, even though the result was always 0. I suppose I should research more on the allocation and deallocation of pages to tables stored as a heap, but I haven't, and my original assumption that a table stored as a heap with no rows would only need to read one page to answer any query was definitely proven wrong. It's likely that some sort of physical defragmentation of the table may have cleaned that up, but it seemed that the easiest answer was to put a clustered index on the table. After doing so, the execution plan showed a cluster index scan, and the IO stats showed only a single page read. (I aborted my first attempt at adding a clustered index on the table because it was taking too long - instead I ran TRUNCATE TABLE Integration.MergePolicy first and added the clustered index, both of which took very little time). I suspect I may not have noticed this if I had used TRUNCATE TABLE Integration.MergePolicy instead of DELETE FROM Integration.MergePolicy, since I'm guessing that the truncate operation does some rather quick releasing of pages allocated to the heap table. In the future, I will likely be much more careful to have a clustered index on every table I use, even the working tables. Mike  

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  • SQL Server - Rebuilding Indexes

    - by Renso
    Goal: Rebuild indexes in SQL server. This can be done one at a time or with the example script below to rebuild all index for a specified table or for all tables in a given database. Why? The data in indexes gets fragmented over time. That means that as the index grows, the newly added rows to the index are physically stored in other sections of the allocated database storage space. Kind of like when you load your Christmas shopping into the trunk of your car and it is full you continue to load some on the back seat, in the same way some storage buffer is created for your index but once that runs out the data is then stored in other storage space and your data in your index is no longer stored in contiguous physical pages. To access the index the database manager has to "string together" disparate fragments to create the full-index and create one contiguous set of pages for that index. Defragmentation fixes that. What does the fragmentation affect?Depending of course on how large the table is and how fragmented the data is, can cause SQL Server to perform unnecessary data reads, slowing down SQL Server’s performance.Which index to rebuild?As a rule consider that when reorganize a table's clustered index, all other non-clustered indexes on that same table will automatically be rebuilt. A table can only have one clustered index.How to rebuild all the index for one table:The DBCC DBREINDEX command will not automatically rebuild all of the indexes on a given table in a databaseHow to rebuild all indexes for all tables in a given database:USE [myDB]    -- enter your database name hereDECLARE @tableName varchar(255)DECLARE TableCursor CURSOR FORSELECT table_name FROM information_schema.tablesWHERE table_type = 'base table'OPEN TableCursorFETCH NEXT FROM TableCursor INTO @tableNameWHILE @@FETCH_STATUS = 0BEGINDBCC DBREINDEX(@tableName,' ',90)     --a fill factor of 90%FETCH NEXT FROM TableCursor INTO @tableNameENDCLOSE TableCursorDEALLOCATE TableCursorWhat does this script do?Reindexes all indexes in all tables of the given database. Each index is filled with a fill factor of 90%. While the command DBCC DBREINDEX runs and rebuilds the indexes, that the table becomes unavailable for use by your users temporarily until the rebuild has completed, so don't do this during production  hours as it will create a shared lock on the tables, although it will allow for read-only uncommitted data reads; i.e.e SELECT.What is the fill factor?Is the percentage of space on each index page for storing data when the index is created or rebuilt. It replaces the fill factor when the index was created, becoming the new default for the index and for any other nonclustered indexes rebuilt because a clustered index is rebuilt. When fillfactor is 0, DBCC DBREINDEX uses the fill factor value last specified for the index. This value is stored in the sys.indexes catalog view. If fillfactor is specified, table_name and index_name must be specified. If fillfactor is not specified, the default fill factor, 100, is used.How do I determine the level of fragmentation?Run the DBCC SHOWCONTIG command. However this requires you to specify the ID of both the table and index being. To make it a lot easier by only requiring you to specify the table name and/or index you can run this script:DECLARE@ID int,@IndexID int,@IndexName varchar(128)--Specify the table and index namesSELECT @IndexName = ‘index_name’    --name of the indexSET @ID = OBJECT_ID(‘table_name’)  -- name of the tableSELECT @IndexID = IndIDFROM sysindexesWHERE id = @ID AND name = @IndexName--Show the level of fragmentationDBCC SHOWCONTIG (@id, @IndexID)Here is an example:DBCC SHOWCONTIG scanning 'Tickets' table...Table: 'Tickets' (1829581556); index ID: 1, database ID: 13TABLE level scan performed.- Pages Scanned................................: 915- Extents Scanned..............................: 119- Extent Switches..............................: 281- Avg. Pages per Extent........................: 7.7- Scan Density [Best Count:Actual Count].......: 40.78% [115:282]- Logical Scan Fragmentation ..................: 16.28%- Extent Scan Fragmentation ...................: 99.16%- Avg. Bytes Free per Page.....................: 2457.0- Avg. Page Density (full).....................: 69.64%DBCC execution completed. If DBCC printed error messages, contact your system administrator.What's important here?The Scan Density; Ideally it should be 100%. As time goes by it drops as fragmentation occurs. When the level drops below 75%, you should consider re-indexing.Here are the results of the same table and clustered index after running the script:DBCC SHOWCONTIG scanning 'Tickets' table...Table: 'Tickets' (1829581556); index ID: 1, database ID: 13TABLE level scan performed.- Pages Scanned................................: 692- Extents Scanned..............................: 87- Extent Switches..............................: 86- Avg. Pages per Extent........................: 8.0- Scan Density [Best Count:Actual Count].......: 100.00% [87:87]- Logical Scan Fragmentation ..................: 0.00%- Extent Scan Fragmentation ...................: 22.99%- Avg. Bytes Free per Page.....................: 639.8- Avg. Page Density (full).....................: 92.10%DBCC execution completed. If DBCC printed error messages, contact your system administrator.What's different?The Scan Density has increased from 40.78% to 100%; no fragmentation on the clustered index. Note that since we rebuilt the clustered index, all other index were also rebuilt.

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  • What free space thresholds/limits are advisable for 640 GB and 2 TB hard disk drives with ZEVO ZFS on OS X?

    - by Graham Perrin
    Assuming that free space advice for ZEVO will not differ from advice for other modern implementations of ZFS … Question Please, what percentages or amounts of free space are advisable for hard disk drives of the following sizes? 640 GB 2 TB Thoughts A standard answer for modern implementations of ZFS might be "no more than 96 percent full". However if apply that to (say) a single-disk 640 GB dataset where some of the files most commonly used (by VirtualBox) are larger than 15 GB each, then I guess that blocks for those files will become sub optimally spread across the platters with around 26 GB free. I read that in most cases, fragmentation and defragmentation should not be a concern with ZFS. Sill, I like the mental picture of most fragments of a large .vdi in reasonably close proximity to each other. (Do features of ZFS make that wish for proximity too old-fashioned?) Side note: there might arise the question of how to optimise performance after a threshold is 'broken'. If it arises, I'll keep it separate. Background On a 640 GB StoreJet Transcend (product ID 0x2329) in the past I probably went beyond an advisable threshold. Currently the largest file is around 17 GB –  – and I doubt that any .vdi or other file on this disk will grow beyond 40 GB. (Ignore the purple masses, those are bundles of 8 MB band files.) Without HFS Plus: the thresholds of twenty, ten and five percent that I associate with Mobile Time Machine file system need not apply. I currently use ZEVO Community Edition 1.1.1 with Mountain Lion, OS X 10.8.2, but I'd like answers to be not too version-specific. References, chronological order ZFS Block Allocation (Jeff Bonwick's Blog) (2006-11-04) Space Maps (Jeff Bonwick's Blog) (2007-09-13) Doubling Exchange Performance (Bizarre ! Vous avez dit Bizarre ?) (2010-03-11) … So to solve this problem, what went in 2010/Q1 software release is multifold. The most important thing is: we increased the threshold at which we switched from 'first fit' (go fast) to 'best fit' (pack tight) from 70% full to 96% full. With TB drives, each slab is at least 5GB and 4% is still 200MB plenty of space and no need to do anything radical before that. This gave us the biggest bang. Second, instead of trying to reuse the same primary slabs until it failed an allocation we decided to stop giving the primary slab this preferential threatment as soon as the biggest allocation that could be satisfied by a slab was down to 128K (metaslab_df_alloc_threshold). At that point we were ready to switch to another slab that had more free space. We also decided to reduce the SMO bonus. Before, a slab that was 50% empty was preferred over slabs that had never been used. In order to foster more write aggregation, we reduced the threshold to 33% empty. This means that a random write workload now spread to more slabs where each one will have larger amount of free space leading to more write aggregation. Finally we also saw that slab loading was contributing to lower performance and implemented a slab prefetch mechanism to reduce down time associated with that operation. The conjunction of all these changes lead to 50% improved OLTP and 70% reduced variability from run to run … OLTP Improvements in Sun Storage 7000 2010.Q1 (Performance Profiles) (2010-03-11) Alasdair on Everything » ZFS runs really slowly when free disk usage goes above 80% (2010-07-18) where commentary includes: … OpenSolaris has changed this in onnv revision 11146 … [CFT] Improved ZFS metaslab code (faster write speed) (2010-08-22)

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  • Windows 7 inbuilt and 3rd party (de)fragmentation related queries

    - by Karan
    I have a pretty good idea of how files end up getting fragmented. That said, I just copied ~3,200 files of varying sizes (from a few KB to ~20GB) from an external USB HDD to an internal, freshly formatted (under Windows 7 x64), NTFS, 2TB, 5400RPM, WD, SATA, non-system (i.e. secondary) drive, filling it up 57%. Since it should have been very much possible for each file to have been stored in one contiguous block, I expected the drive to be fragmented not more than 1-2% at most after this rather lengthy exercise (unfortunately this older machine doesn't support USB 3.0). Windows 7's inbuilt defrag utility told me after a quick analysis that the drive was fragmented only 1% or so, which dovetailed neatly with my expectations. However, just out of curiosity I downloaded and ran the latest portable x64 version of Piriform's Defraggler, and was shocked to see the drive being reported as being ~85% fragmented! The portable version of Auslogics Disk Defrag also agreed with Defraggler, and both clearly expected to grind away for ~10 hours to completely defragment the drive. 1) How in blazes could the inbuilt and 3rd party defrag utils disagree so badly? I mean, 10-20% variance is probably understandable, but 1% and 85% are miles apart! This Engineering Windows 7 blog post states: In Windows XP, any file that is split into more than one piece is considered fragmented. Not so in Windows Vista if the fragments are large enough – the defragmentation algorithm was changed (from Windows XP) to ignore pieces of a file that are larger than 64MB. As a result, defrag in XP and defrag in Vista will report different amounts of fragmentation on a volume. ... [Please read the entire post so the quote is not taken out of context.] Could it simply be that the 3rd party defrag utils ignore this post-XP change and continue to use analysis algos similar to those XP used? 2) Assuming that the 3rd party utils aren't lying about the real extent of fragmentation (which Windows is downplaying post-XP), how could the files have even got fragmented so badly given they were just copied over afresh to an empty drive? 3) If vastly differing analysis algos explain the yawning gap, which do I believe? I'm no defrag fanatic for sure, but 85% is enough to make me seriously consider spending 10 hours defragging this drive. On the other hand, 1% reported by Windows' own defragger clearly implies that there is no cause for concern and defragging would actually have negative consequences (as per the post). Is Windows' assumption valid and should I just let it be, or will there be any noticeable performance gains after running one of the 3rd party utils for 10 hours straight? 4) I see that out of the box Windows 7 defrag is scheduled to run weekly. Does anyone know whether it defrags every single time, or only if its analysis reveals a fragmentation percentage over a set threshold? If the latter, what is this threshold and can it be changed, maybe via a Registry edit? Thanks for reading through (my first query on this wonderful site!) and for any helpful replies. Also, if you're answering question #3, please keep in mind that any speed increases post defragging with 3rd party utils vis-à-vis Windows' inbuilt program should not include pre-Vista (preferably pre-Win7) examples. Further, examples of programs that made your system boot faster won't help in this case, since this is a non-system drive (although one that'll still be used daily).

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  • 10 Windows Tweaking Myths Debunked

    - by Chris Hoffman
    Windows is big, complicated, and misunderstood. You’ll still stumble across bad advice from time to time when browsing the web. These Windows tweaking, performance, and system maintenance tips are mostly just useless, but some are actively harmful. Luckily, most of these myths have been stomped out on mainstream sites and forums. However, if you start searching the web, you’ll still find websites that recommend you do these things. Erase Cache Files Regularly to Speed Things Up You can free up disk space by running an application like CCleaner, another temporary-file-cleaning utility, or even the Windows Disk Cleanup tool. In some cases, you may even see an old computer speed up when you erase a large amount of useless files. However, running CCleaner or similar utilities every day to erase your browser’s cache won’t actually speed things up. It will slow down your web browsing as your web browser is forced to redownload the files all over again, and reconstruct the cache you regularly delete. If you’ve installed CCleaner or a similar program and run it every day with the default settings, you’re actually slowing down your web browsing. Consider at least preventing the program from wiping out your web browser cache. Enable ReadyBoost to Speed Up Modern PCs Windows still prompts you to enable ReadyBoost when you insert a USB stick or memory card. On modern computers, this is completely pointless — ReadyBoost won’t actually speed up your computer if you have at least 1 GB of RAM. If you have a very old computer with a tiny amount of RAM — think 512 MB — ReadyBoost may help a bit. Otherwise, don’t bother. Open the Disk Defragmenter and Manually Defragment On Windows 98, users had to manually open the defragmentation tool and run it, ensuring no other applications were using the hard drive while it did its work. Modern versions of Windows are capable of defragmenting your file system while other programs are using it, and they automatically defragment your disks for you. If you’re still opening the Disk Defragmenter every week and clicking the Defragment button, you don’t need to do this — Windows is doing it for you unless you’ve told it not to run on a schedule. Modern computers with solid-state drives don’t have to be defragmented at all. Disable Your Pagefile to Increase Performance When Windows runs out of empty space in RAM, it swaps out data from memory to a pagefile on your hard disk. If a computer doesn’t have much memory and it’s running slow, it’s probably moving data to the pagefile or reading data from it. Some Windows geeks seem to think that the pagefile is bad for system performance and disable it completely. The argument seems to be that Windows can’t be trusted to manage a pagefile and won’t use it intelligently, so the pagefile needs to be removed. As long as you have enough RAM, it’s true that you can get by without a pagefile. However, if you do have enough RAM, Windows will only use the pagefile rarely anyway. Tests have found that disabling the pagefile offers no performance benefit. Enable CPU Cores in MSConfig Some websites claim that Windows may not be using all of your CPU cores or that you can speed up your boot time by increasing the amount of cores used during boot. They direct you to the MSConfig application, where you can indeed select an option that appears to increase the amount of cores used. In reality, Windows always uses the maximum amount of processor cores your CPU has. (Technically, only one core is used at the beginning of the boot process, but the additional cores are quickly activated.) Leave this option unchecked. It’s just a debugging option that allows you to set a maximum number of cores, so it would be useful if you wanted to force Windows to only use a single core on a multi-core system — but all it can do is restrict the amount of cores used. Clean Your Prefetch To Increase Startup Speed Windows watches the programs you run and creates .pf files in its Prefetch folder for them. The Prefetch feature works as a sort of cache — when you open an application, Windows checks the Prefetch folder, looks at the application’s .pf file (if it exists), and uses that as a guide to start preloading data that the application will use. This helps your applications start faster. Some Windows geeks have misunderstood this feature. They believe that Windows loads these files at boot, so your boot time will slow down due to Windows preloading the data specified in the .pf files. They also argue you’ll build up useless files as you uninstall programs and .pf files will be left over. In reality, Windows only loads the data in these .pf files when you launch the associated application and only stores .pf files for the 128 most recently launched programs. If you were to regularly clean out the Prefetch folder, not only would programs take longer to open because they won’t be preloaded, Windows will have to waste time recreating all the .pf files. You could also modify the PrefetchParameters setting to disable Prefetch, but there’s no reason to do that. Let Windows manage Prefetch on its own. Disable QoS To Increase Network Bandwidth Quality of Service (QoS) is a feature that allows your computer to prioritize its traffic. For example, a time-critical application like Skype could choose to use QoS and prioritize its traffic over a file-downloading program so your voice conversation would work smoothly, even while you were downloading files. Some people incorrectly believe that QoS always reserves a certain amount of bandwidth and this bandwidth is unused until you disable it. This is untrue. In reality, 100% of bandwidth is normally available to all applications unless a program chooses to use QoS. Even if a program does choose to use QoS, the reserved space will be available to other programs unless the program is actively using it. No bandwidth is ever set aside and left empty. Set DisablePagingExecutive to Make Windows Faster The DisablePagingExecutive registry setting is set to 0 by default, which allows drivers and system code to be paged to the disk. When set to 1, drivers and system code will be forced to stay resident in memory. Once again, some people believe that Windows isn’t smart enough to manage the pagefile on its own and believe that changing this option will force Windows to keep important files in memory rather than stupidly paging them out. If you have more than enough memory, changing this won’t really do anything. If you have little memory, changing this setting may force Windows to push programs you’re using to the page file rather than push unused system files there — this would slow things down. This is an option that may be helpful for debugging in some situations, not a setting to change for more performance. Process Idle Tasks to Free Memory Windows does things, such as creating scheduled system restore points, when you step away from your computer. It waits until your computer is “idle” so it won’t slow your computer and waste your time while you’re using it. Running the “Rundll32.exe advapi32.dll,ProcessIdleTasks” command forces Windows to perform all of these tasks while you’re using the computer. This is completely pointless and won’t help free memory or anything like that — all you’re doing is forcing Windows to slow your computer down while you’re using it. This command only exists so benchmarking programs can force idle tasks to run before performing benchmarks, ensuring idle tasks don’t start running and interfere with the benchmark. Delay or Disable Windows Services There’s no real reason to disable Windows services anymore. There was a time when Windows was particularly heavy and computers had little memory — think Windows Vista and those “Vista Capable” PCs Microsoft was sued over. Modern versions of Windows like Windows 7 and 8 are lighter than Windows Vista and computers have more than enough memory, so you won’t see any improvements from disabling system services included with Windows. Some people argue for not disabling services, however — they recommend setting services from “Automatic” to “Automatic (Delayed Start)”. By default, the Delayed Start option just starts services two minutes after the last “Automatic” service starts. Setting services to Delayed Start won’t really speed up your boot time, as the services will still need to start — in fact, it may lengthen the time it takes to get a usable desktop as services will still be loading two minutes after booting. Most services can load in parallel, and loading the services as early as possible will result in a better experience. The “Delayed Start” feature is primarily useful for system administrators who need to ensure a specific service starts later than another service. If you ever find a guide that recommends you set a little-known registry setting to improve performance, take a closer look — the change is probably useless. Want to actually speed up your PC? Try disabling useless startup programs that run on boot, increasing your boot time and consuming memory in the background. This is a much better tip than doing any of the above, especially considering most Windows PCs come packed to the brim with bloatware.     

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