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  • Pentium 4 Willamette vs. Faster Celeron Northwood [closed]

    - by Synetech inc.
    Which is the preferable of the following two processors? Intel® Pentium® 4 Processor 1.70 GHz, 256K Cache, 400 MHz FSB Willamette Intel® Celeron® Processor 2.40 GHz, 128K Cache, 400 MHz FSB Northwood Details: A few months ago my motherboard died, so I bought a used computer that had a 2.4GHz Celeron. My old system had a 1.7GHz Pentium 4, so now I’m trying to decide which CPU to use. Obviously a P4 is preferable over a Celeron, but the Celeron is (significantly?) faster than the P4. I’m wondering if the faster Celeron might be better for certain tasks (ie, stronger but dumber is better at some things than smarter but weaker). I tried Googling for some reviews and comparisons for graphs to get a clear depiction of which is better overall, but found nothing that helped. (I did manage to find one page that indicates (apparently by poll, not benchmark) that the Celeron is better.) So which CPU should I use? Does anyone know of some graphs that I can use to compare the two? The system is a general-purpose machine for word-processing, Internet, and casual games (not Crysis, but not Solitaire either). It will be running Windows XP. The board is a 478 with 400MHz FSB.

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  • RAID 5 Install on Ubuntu Server 12.04 [closed]

    - by tarabyte
    Environment: Ubuntu Server 12.04, installing from bootable flash drive Error: No root file system is defined. Please correct this from the partitioning menu. I'm trying to set up a personal file server with software RAID 5. I just got three hard drives for this, but haven't found any solid documentation. I'm unsure what the basic way to partition my hard drives is. Can someone upload a screenshot of their "partition disks" screen so that I can compare with mine (attached)? Should I set the bootable flag? Do I need a /home partition? A /boot partition? Should I "Use [my partition] as: Ext4 journaling file system"? Or make that field "physical volume for RAID"? I am an engineer, but I have only a cursory knowledge of all-things-linux. If you know of any good learning resources I'd be happy to hear about those too (that way I don't have to blindly follow deprecated tutorials online). well, image would be here but i don't have a high enough reputation yet (please vote up :)) Thank you, References I've looked into: https://help.ubuntu.com/community/Installation/SoftwareRAID https://help.ubuntu.com/12.04/serverguide/advanced-installation.html http://forevergeeks.com/setup-ubuntu-server-with-raid-5/

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  • Read access to Active Directory property (uSNCreated)

    - by Tom Ligda
    I have an issue with read access to the uSNCreated property when doing LDAP searches. If I do an LDAP search with a user that is a member of the Domain Admins group (UserA), I can see the uSNCreated property for every user. The problem is that if I do an LDAP search with a user (UserB) that is not a member of the Domain Admins group, I can see the uSNCreated property for some users (UserGroupA) and not for some users (UserGroupB). When I look at the users in UserGroupA and compare them to the users in UserGroupB, I see a crucial difference in the "Security" tab. The users in UserGroupA have the "Include inheritable permissions from this object's parent" unchecked. The users in UserGroupB have that option checked. I also noticed that the users in UserGroupA are users that were created earlier. The users in UserGroupB are users created recently. It's difficult to quantify, but I estimate the border between creation time between the users in UserGroupA and UserGroupB is about 6 months ago. What can cause the user creation to default to having that security property checked as opposed to unchecked? A while back (maybe around 6 months ago?) I changed the domain functional level from Windows Server 2003 to Windows Server 2008 R2. Would that have had this effect? (I can't exactly downgrade the domain functional level to test it out.) Is this security property actually the cause of the issue with read access to the uSNChanged property on LDAP searches? It seems correlated, but I'm not sure about causation. What I want in the end is for all authenticated users to have read access to the uSNCreated property for all users when doing an LDAP search. I would also be OK if I could grant read access for that property to an AD group. Then I can control access by adding members to the group.

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  • PHP/MySQL Performance Testing with Just PHP

    - by Mike Gifford
    I'm trying to diagnose a server where the website is loading very slowly, but unfortunately my client has only provided me with FTP access. I've got FTP access so I can upload PHP scripts, but can't set up any other server side tools. I have access to phpMyAdmin, but not direct access to the MySQL server. It is also unfortunately a Windows server (and we've been a Linux shop for over a decade now). So, if I wan to evaluate MySQL & disk speed performance through PHP on a generic server, what is the best way to do this? There are already tools like: https://github.com/raphaelm/php-benchmark or https://github.com/InfinitySoft/php-benchmark But I'm surprised there isn't something that someone has already set up & configured to just run through and do some basic testing of a server's responsiveness. Every time we evaluate a new server environment it's handy to be able to compare it to an existing one quickly to see if there are any anomalies. I guess I'd just hoped that someone else had written up a script to do this already. I know I have, but that was before Github when there was a handy place to post scraps of code like this. Originally posted in http://stackoverflow.com/questions/12321498/php-mysql-performance-testing-with-just-php but it was recommended that I re-post it here.

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  • How to utilize Varnish for A/B Testing and Feature Rollout?

    - by Ken
    Hi all, wasn't really sure if this should go here on or stackoverlow - admins, please move if i'm mistaken (and sorry). Today we have our web layer exposed to the world. We would like to add Varnish in front of our web layer to accelerate the site and reduce calls to the backend. However, we have some concerns and i was wondering how most people approach them: A/B Testing - How do you test two "versions" of each page and compare? I mean, how does varnish know which page to serve up? If and how do you save seperate versions on each page? Feature rollout - how would you set up a simple feature rollout mechanism? Let's say i want to open a new feature/page to just 10% of the traffic.. and then later increase that to 20%? How do you handle code deployments? Do you purge your entire varnish cache every deployment? (We have deployments on a daily basis). Or do you just let it slowly expire (using TTL)? Any ideas and examples regarding these issues is greatly appreciated! Thanks in advance. Ken.

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  • LDAP Authentication woes

    - by Marcelo de Moraes Serpa
    Hello list, I have a local OpenLDAP server with a couple of users. I'm using it for development purposes, here's the ldif: #Top level - the organization dn: dc=site, dc=com dc: site description: My Organization objectClass: dcObject objectClass: organization o: Organization #Top level - manager dn: cn=Manager, dc=site, dc=com objectClass: organizationalRole cn: Manager #Second level - organizational units dn: ou=people, dc=site, dc=com ou: people description: All people in the organization objectClass: organizationalunit dn: ou=groups, dc=site, dc=com ou: groups description: All groups in the organization objectClass: organizationalunit #Third level - people dn: uid=celoserpa, ou=people, dc=site, dc=com objectclass: pilotPerson objectclass: uidObject uid: celoserpa cn: Marcelo de Moraes Serpa sn: de Moraes Serpa userPassword: secret_12345 mail: [email protected] So far, so good. I can bind with "cn=Manager,dc=site,dc=com" and the 12345678 password (the local server password, setup on slapd.conf). However, I would like to bind with any user in under the people OU. In this case, I'd like to bind with: dn: uid=celoserpa, ou=people, dc=site, dc=com userPassword: secret_12345 But I'm getting a "(49) - Invalid Credentials" error everytime. I have tried through CLI tools (such as ldapadd, ldapwhoami, etc) and also ruby/ldap. The bind with these credentials fails with a invalid credentials error. I thought that it could be an ACL issue, however, the ACLs on slapd.conf seem to be right: access to attrs=userPassword by self write by dn.sub="ou=people,dc=site,dc=com" read by anonymous auth access to * by * read I was suspecting that maybe OpenLDAP doesn't compare against userPassword? Or maybe some ACL configuration I am missing that is somehow affecting the read access to userPassword for the specific DN. I'm really lost here, any suggestion appreciated! Cheers, Marcelo.

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  • Format & Fresh Install Mac os x snow leopard in mac mini.

    - by sagar
    Hello Every one. I have purchased dvd of Snow leopard 10.6.2. But actually I purchased mac mini with 10.5.7 leopard I tried to install snow leopard 10.6.2. Everything went perfectly. system was installed successfully. But the problem that I faced is as follows. System was installed but my older data remained as it is. ( means installation didn't format every thing - means installation was done on upgrade basis. ) Now, my system works with very low speed. Previous performance of mac mini was double as compare to current upgrade version. Now - my question are as follows. Does upgrade installation causes the performance in specially osx ? ( means anyone faced this kind of problem ? ) Or 10.6.2 snow leopard is heavy weight system for mac mini ? ( 2Ghz Intel core2duo,1GB RAM - is this configuration OK for snow leopard 10.6.2 ? ) Fresh install works better then upgrade in os x ?

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  • Format & Fresh Install Mac OS X Snow Leopard on Mac mini.

    - by sagar
    Hello Every one. I have purchased a DVD of Snow Leopard (Mac OS X 10.6.2) I purchased a Mac mini with Leopard (Mac OS X 10.5.7) I tried to install Mac OS X 10.6.2 Everything went perfectly. System was installed successfully. But the problem that I faced is as follows. System was installed but my older data remained as it is. (means installation didn't format every thing - means installation was done on upgrade basis.) Now, my system works with very low speed. Previous performance of Mac mini was double as compare to current upgrade version. Now - my question are as follows. Does an upgrade installation causes the performance issues in Mac OS X? Or is Snow Leopard too demanding for the Mac mini? ( 2 Ghz Intel Core 2 Duo, 1GB RAM - is this configuration OK for Snow Leopard? ) Does a fresh install work better than an upgrade?

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  • Software mirroring (RAID1) versus "Fake Raid" for new Windows 7 install

    - by kquinn
    I've just ordered two new hard drives for my main desktop and a copy of Windows 7 Professional 64-bit. I'd like to do a clean install of Win7 onto the new drives (leaving my old XP Pro boot partition around for a while in case something goes disastrously wrong, etc.). I want to have them set up in mirrored (RAID-1) mode. My understanding is that Win7 Pro can do software mirroring, but can I set this up directly at install time? If so, how? Note that I'd like the disk to be split into three partitions (OS/Apps&Data/Bulk data), all of which should be mirrored. Would it be better (more reliable or faster) to use my motherboard's hardware RAID support? My motherboard is an older nVidia nForce 680i SLI, which is not the most stable of motherboards, and I'm not sure how trustworthy its RAID1 configuration might be (or if Win7 could even detect and install onto a hardware-mirrored volume). Also, the performance characteristics of RAID1 are rather different than RAID0 or RAID5, and I'm wondering if Win7's software mirroring might actually be faster than hardware RAID1 (for example, I'm more of a Unix admin when I have to wear the sysadmin hat, and I've had great success deploying ZFS; most hardware RAID1 implementations have to read both disks and compare results to look for data errors, but ZFS can read from only one disk in the mirror and just use the built-in checksum, meaning it can have up to 2x the number of reads in-flight, as long as there's no data corruption). Edit: Okay, my question about whether Windows 7 can do software mirroring has been answered, and it can. I'm still unsure whether Windows software RAID or my motherboard's hardware "fake RAID" function is a better choice, though. Remember, I'm only interested in mirroring -- not the more complicated striping or parity operations that generally show the poor performance of crappy motherboard RAID solutions.

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  • Nginx Slower than Apache??

    - by ichilton
    Hi, I've just setup 2x identical Rackspace Cloud instances and am doing some comparisons and benchmarks to compare Apache and Nginx. I'm testing with a 3.4k png file and initially 512MB server instances but have now moved to 1024MB server instances. I'm very surprised to see that whatever I try, Apache seems to consistently outperform Nginx....what am I doing wrong? Nginx: Server Software: nginx/0.8.54 Server Port: 80 Document Length: 3400 bytes Concurrency Level: 100 Time taken for tests: 2.320 seconds Complete requests: 1000 Failed requests: 0 Write errors: 0 Total transferred: 3612000 bytes HTML transferred: 3400000 bytes Requests per second: 431.01 [#/sec] (mean) Time per request: 232.014 [ms] (mean) Time per request: 2.320 [ms] (mean, across all concurrent requests) Transfer rate: 1520.31 [Kbytes/sec] received Connection Times (ms) min mean[+/-sd] median max Connect: 0 11 15.7 3 120 Processing: 1 35 76.9 20 1674 Waiting: 1 31 73.0 19 1674 Total: 1 46 79.1 21 1693 Percentage of the requests served within a certain time (ms) 50% 21 66% 39 75% 40 80% 40 90% 98 95% 136 98% 269 99% 334 100% 1693 (longest request) And Apache: Server Software: Apache/2.2.16 Server Port: 80 Document Length: 3400 bytes Concurrency Level: 100 Time taken for tests: 1.346 seconds Complete requests: 1000 Failed requests: 0 Write errors: 0 Total transferred: 3647000 bytes HTML transferred: 3400000 bytes Requests per second: 742.90 [#/sec] (mean) Time per request: 134.608 [ms] (mean) Time per request: 1.346 [ms] (mean, across all concurrent requests) Transfer rate: 2645.85 [Kbytes/sec] received Connection Times (ms) min mean[+/-sd] median max Connect: 0 1 3.7 0 27 Processing: 0 3 6.2 1 29 Waiting: 0 2 5.0 1 29 Total: 1 4 7.0 1 29 Percentage of the requests served within a certain time (ms) 50% 1 66% 1 75% 1 80% 1 90% 17 95% 19 98% 26 99% 27 100% 29 (longest request) I'm currently using worker_processes 4; and worker_connections 1024; but i've tried and benchmarked different values and see the same behaviour on all - I just can't get it to perform as well as Apache and from what i've read previously, i'm shocked about this! Can anyone give any advice? Thanks, Ian

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  • The bottlenecks of any computer, what to look for?

    - by WebDevHobo
    Whether it is a laptop or a desktop, any computer is made up of several pieces of hardware that communicate with each other. Sending data back and forth to ensure that the user gets the desired results. I have seen some theoretical stuff on computers & hardware, but I wonder how it all comes together. CPU RAM Graphics Card L1 CACHE L2 CACHE L3 CACHE FSB ... And all other things. Which is the biggest bottle neck? Why would a person not want/need a big value in one of those categories in certain situations? P.S.: when reading the specs of the i5 750 processor, I came across this description: In place of the FSB, one or more high speed, point-to-point buses called Quick Path Interconnect (QPI) are used, formerly known as Common Serial Interconnect Bus or CSI. QPI features higher bandwidth than the traditional FSB and is better suited to system scaling. What is this, and how does it compare to FSB? EDIT: I am not planning to buy a computer at all. The goal of this question is to understand the internal relation of various hardware pieces, their specific functions and how they work together. For instance, I have heard to a somewhat higher-than-usual amount of L2/L3 Cache can help speed up your computer. What's up with saying that? Also I forgot to mention Hard-disk RPM.

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  • Choosing a new laptop

    - by chiongms
    I'm looking for a new laptop. I saw few: i) HP ProBook 4321s ii) HP ProBook 6440b iii)Dell Latitude E6410 i found these laptops are still very new..is it? not much comments about them. can anyone help? i doubt how their graphic cards perform compare to each other? ProBook 4321s- Radeon HD4350 ProBook 6440b- Radeon HD4550 Latitude E6410- NVS 3100M most of the time i'll running 3D CAD software, C++ programing...i saw my friend's laptop with radeon HD4350. it's perfectly fulfilling my demand. but i wonder how the other two are? Another thing i doubt is the screen resolution..my current laptop is 1280x800, and i found it comfortable to use. But these two HP only offer 1366x768..will it make any large different? Lastly, is there anyway to estimate how their power consumption is from the spec sheet? well, i would prefer one with longer battery usage time. my current laptop is suck...only last 1 hour even when it's still new..i'm not going to get another like this anymore. Anyone can help me please? Thanks!

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  • Why are Microsoft Windows Update taking so long to install?

    - by Mathieu Pagé
    Hi, I have a question that is not related to a problem I have. Just something I'd like to understand. Why are Windows update so long? First Windows Update need to find witch updates you needs and this take about 5 minutes. What is happening behind the scene during those 5 minutes? I would have tought that it would be enough to compare the updates you already have to the complete list of updates or to check the version numbers of a couples files. Then when it comes time to install the upgrades, they're also taking a long time. Some 1 Mb updates takes 2, 3 or 5 minutes to install. What is taking so long. I would have though that it was simply a mater of backup the old file, uncompress the new files, replace the old file. This should be really fast. Is Windows doing something else? For comparison, under Linux, you can find which updates you need in about 20 seconds and installing them is usually pretty fast (The time to uncompress the files). I can do a complete updgrade of my linux machine in about 25 minutes (download 600-800 Mb of updates, hundreds of them and install them) while under windows 25 minutes is the time it needs to find witch update are needed and install about 5-10 updates. I just updated a Windows XP home from SP1a to SP3 + all other updates. It took me more than 3 hours. Doing something like that in the Linux World takes about 30 minutes. I don't want to bash Microsoft here. I genuinly want to know what they do differently that makes it so long.

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  • Identify differences between MP3 files

    - by Thingomy
    I have 2 old similar directory trees with MP3 files in them. I am happily using tools like diff and Rsync to identify and merge the files that are only present on one side, or are identical, I'm left with a bunch of files that are bitwise different. On running diff over a pair actually different files, (with -a tag to force text analysis) it produces incomprehensible gibberish. I have listened to files from both sides, and they both seem to play fine (but at nearly 10 minutes per song, when listening to them twice each, I haven't done many) I suspect the differences are due to some player in the past "enhancing" my collection by messing about with ID3 tags, but I can't be certain. Even if I identify differences in ID3 tags, I would like to confirm that no cosmic ray or file copy error issues have damaged any of the files. One method that occurs to be is finding the byte locations of the differences, and ignoring all changes in the first ~10kb of each file, but I don't know how to do this. I have on the order of a hundred or so files that differ across the directory tree. I found How to compare mp3, flac audio data in a file, ignoring header data (ID3 tag) etc.? -- but I can't run alldup due to being Linux only, and from the sounds of it, it would only partially solve my issues anyway.

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  • Formula to calculate probability of unrecoverable read error during RAID rebuild

    - by OlafM
    I need to compare the reliability of different RAID systems with either consumer or enterprise drives. The formula to have the probability of success of a rebuild, ignoring mechanical problems, is simple: error_probability = 1 - (1-per_bit_error_rate)^bit_read and with 3 TB drives I get 38% probability to experience an URE (unrecoverable read error) for a 2+1 disks RAID5 (4.7% for enterprise drives) 21% for a RAID1 (2.4% for enterprise drives) 51% probability of error during recovery for the 3+1 RAID5 often used by users of SOHO products like Synologys. Most people don't know about this. Calculating the error for single disk tolerance is easy, my question concerns systems tolerant to multiple disks failures (RAID6/Z2, RAIDZ3 and RAID1 with multiple disks). If only the first disk is used for rebuild and the second one is read again from the beginning in case or an URE, then the error probability is the one calculated above squared (14.5% for consumer RAID5 2+1, 4.5% for consumer RAID1 1+2). However, I suppose (at least in ZFS that has full checksums!) that the second parity/available disk is read only where needed, meaning that only few sectors are needed: how many UREs can possibly happen in the first disk? not many, otherwise the error probability for single-disk tolerance systems would skyrocket even more than I calculated. If I'm correct, a second parity disk would practically lower the risk to extremely low values. Am I correct?

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  • Synchronizing files between Linux servers, through FTP

    - by Daniel Magliola
    I have the following configuration of servers: 1 central linux server, a VPS 8 satellite linux servers, "crappy shared hostings" I have a bunch of files that I need to have in all servers. Right now i'm copying them everywhere manually, but I want to be able to copy them to the central server, and then have a scheduled process that runs every now and then and synchronizes them (only outwardly, no need to try to find "new" files in the satellite servers). There are a couple of catches though: I can't have any custom software in the satellite servers, or do strange command line things that'll auto connect to them and send the files directly. I know this is the way these kinds of things are normally done, but the satellite servers are crappy shared hosting ones where I have absolutely no control over anything. I need to send the files over FTP I also need to have, in my central server, a list of the files that are available in each of the satellite servers, to make sure they are ready before I send traffic to them. If I were to do this manually, the steps would be: get the list of files in a satellite server compare to my own, and send the files that are missing get the list of files again, and store it in my central database. I'd like to know what tools are out there that can alleviate as much of this as possible, first the syncing, and then the "getting the list of files available in the other server". I'm going to be doing everything from PHP, not sure if there are good tools to "use FTP from PHP", which i'm pretty sure i'll have to do for step 3 at least. Thanks in advance for any ideas! Daniel

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  • How should I monitor memory usage/performance in SunOS/Solaris?

    - by exhuma
    Last week we decided to add some SunOS (uname -a = SunOS bbs-sam-belair 5.10 Generic_127128-11 i86pc i386 i86pc) machines into our running munin instance. First off, the machines are pre-configured appliances, so, I want to avoid touching the system too much without supervision of the service provider. But adding it to munin was fairly easy by writing a small socket-service (if anyone is interested, I put it up on github: https://github.com/munin-monitoring/contrib/tree/master/tools/pypmmn) Yesterday, I implemented/adapted the required plugins for our machines. And here the questions start: First, I have not found a way to determine detailed memory usage values. I get the total memory by running prtconf | grep Memory, and the free memory using vmstat. Fiddling together a munin-plugin, gives me the following graph: This is pretty much uninformative. Compare this to the default plugin for linux nodes which has a lot more detail: Most importantly, this shows me how much memory is actually used by applications. So, first question: Is it possible to get detailed memory information on SunOS with the default system tools (i.e. not using top)? Onto the next puzzle: Seeing the graphs, I noticed activity in the "Paging in/out" graphs, even though the memory graph still has unused memory: Upon further investigation, I found out that df reports that /tmp is mounted on swap. Drilling around on the web, I understood that df will display swap, but in fact, it's mounted as a tmpfs. Now I don't know if this explains the swap activity. The default munin-plugin for solaris uses kstat -p -c misc -m cpu_stat to get these values. I find it already strange that this is using the cpu_stat module. So maybe I simply misinterpret the "paging" graphs? Second question: Do the paging graphs indicate that parts of the memory are paged to disk? Or is the activity caused by file operations in /tmp?

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  • Replicated MongoDB server slower than simple shards

    - by displayName
    I tried to compare the performance of a sharded configuration against a sharded and replicated configuration. The sharded configuration consists of 8 shards each running on three different machines thereby constituting a total of 24 shards. All 8 of these shards run in the same partition on each machine. The sharded and replicated version is 8 shards again just like plain sharding, and all 8 mongods run on the same partition in each machine. But apart from this, each of these three machine now run additional 16 threads on another partition which serve as the secondary for the 8 mongods running on other machines. This is the way I prepared a sharded and replicated configuration with data chunks having replication factor of 3. Important point to note is that once the data has been loaded, it is not modified. So after primary and secondaries have synchronized then it doesn't matter which one i read from. To run the queries, I use an entirely different machine (let's call it config) which runs mongos and this machine's only purpose is to receive queries and run them on the cluster. Contrary to my expectations, plain sharding of 8 threads on each machine (total = 3 * 8 = 24) is performing better for queries than the sharded + replicated configuration. I have a script written to perform the query. So in order to time the scripts, I use time ./testScript and see the result. I tried changing the reading preference for replicated cluster by logging to mongo of config and run db.getMongo().setReadPref('secondary') and then exit the shell and run the queries like time ./testScript. The questions are: Where am i going wrong in the replication? Why is it slower than its plain sharding version? Does the db.getMongo().ReadPref('secondary') persist when i leave the shell and try to perform the query? All the four machines are running Linux and i have already increased the ulimit -n to 2048 from initial value of 1024 to allow more connections. The collections are properly distributed and all the mongods have equal number of chunks. Goes without saying that indices in both configurations are the same.

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  • What to look for in a reliable backup hard disk?

    - by Senthil
    I want to buy an internal hard disk and use a docking station along with it for backing up important data. The size will be around 500GB to 1TB. I have a budget and several models fit into it. So far, they only seem to vary in size, speed and brand. These are the only things I can compare from the specs. I guess asking for which brand is best is completely subjective so I won't do that. I want my disk to have long life and be reliable. Doesn't matter if it is somewhat slow. Size: Should I go for the one with highest size within my budget? Will higher density cause problems? Or should I go for a moderately sized one? Does the number of platters have an impact? Speed: I do not want high performance. I want it to be reliable and last long. I am definitely not going to choose the expensive 10,000 rpm ones. Should I go for 5400 or 7200? Do these numbers affect longevity and reliability? Are there any other technical and objective factors that I should look for?

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  • How to choose the most optimal RAID settings on PE2950

    - by javano
    I have some Dell PowerEdge 2950's with 4x 15k, 150GB Cheetah SAS drives in them. They are going to be VM hosts, CentOS running ESXi with Windows Server 2k8 guests. Some guests will be hosting IIS servers, and others MSSQL servers. I am trying to set the RAID virtual disks settings and can't decide which is more optimal given this situation; Read Policy: Out of Read-Ahead, No-Read-Ahead and Adaptive Read-Ahead, the default is Read-Ahead. I will be making large sequential writes initially, writing out blank images for virtual machine hard drives (lets say 30GBs from /dev/zero for example) so Read-Ahead seems good at first. But within the virtual machines reads could be random from anywhere within their file systems as they are IIS and MSSQL servers, so perhaps No-Read-Ahead is a better idea? Now I think Adaptive Read-Ahead would be better then as a compromise but I don't know much about this option, how does it compare in performance to the others? Write Policy: write-back caching, write-through caching, the default is write-back caching. The default of write-back caching is safer than write-through caching but at a performance expense. My thinking here is that in the event of power loss for example, it seems more likely in my head (this is why I need some clarification!) that damage will occur to a guest VM with write-back caching enabled, so I should favour write-through? I have searched around and there is obviously no definitive answer, so I would like to find out what is best for my situation.

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  • IIS Digest repeatedly asking for authentication

    - by David Budiac
    I have a development copy of an ASP.NET intranet site checked out and running on my local machine. We're using digest authentication to allow users to log in using their active directory accounts. On my development copy only, Digest sometimes will repeatedly prompt for login information usually ~9 times per page request. After repeatedly logging in (or it also works to cancel out of 8 out of the 9 prompts), I can use the site as normal. I cannot pinpoint what is triggering the issue. Sometimes this problem triggers upon the next page request, sometimes after I edited/saved/refreshed a page, and sometimes it doesn't happen at all. Each prompt triggers several logon (Event ID 4624 & 4672) security events in the Events Viewer. Shortly after each burst of logon events, I'll see a burst of logoff events (Event ID A co-worker who has a nearly an identical setup (Windows 7, IIS 7) is not experiencing the issue. Our production copy (that is running on a different server) also does not experience the issue. We've tried to compare our settings in IIS, not really finding any differences. I'm using chrome but I've experienced the issue in other browsers.

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  • Decyphering Seagate drive model numbers?

    - by Stefan Lasiewski
    I'm comparing Seagate's Enterprise and Desktop drives for a variety of old and new servers. These servers come from different generations, so options like size (73GB, 2TB) and interface (SATA vs SAS 3.0Gbps vs SAS 6Gbps vs SCSI Ultra320) are widely variable. I'm trying to compare the sizes, speeds and interfaces, but I'm getting thrown off by different models. Also, their website is not the best. Does anyone know of a documented explanation of the Seagate model numbers? And is there a single spreadsheet which compares the features for all drives (or all 'Enterprise' drives?). Seagate drives have model numbers like this: Model ST3600057SS 6-Gb/s SAS 600 GB None at Cheetah® 15K Hard Drives Model ST373455LW Ultra320 SCSI 73.4 GB 68-Pin LW at Cheetah® 15K Hard Drives Model ST32000644NS SATA 3Gb/s 2 TB None at Constellation™ ES Hard Drives Model ST973452SS 6-Gb/s SAS 73 GB None Savvio® 15K Hard Drives Model ST9200011FS SATA 3Gb/s 200 GB Pulsar™ Solid State Drives I understand the model numbers read something like this: ST - SOMETHING1 - SIZE - SOMETHING2 - INTERFACE Where the fields mean something like this: ST : For 'Seagate'? 'Seagate Technoligies'? SOMETHING1 - This field has number, but I'm not sure what that represents. SIZE - Size in Gigabytes. This is a number like '73' or '300' or '2000' SOMETHING2 - This field also has a number, but I'm not sure what it means. INTERFACE - This field seems to indicate the Interface. 'SS' means SAS, 'FC' means Fibre Channel, but I don't see how to distinguish between 6Gbps SAS and 3Gbps SAS, or different SATA or FC speeds. I don't see a field which indicates the RPM (15K , 10K, 7.2K) etc. Is this part of the model number?

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  • DNS Round-robin, Load Balancing, Load sharing, and failover in 2012

    - by user1089770
    I have been reading many posts on serverfault as well as on other sites regarding all these. What I understand is, Multiple A records(round-robin dns) can be used for both : Load sharing (round-robin, but NOT load-balancing). Many people say that “Load Balancing” but I think there will be no load-balancing because “Balance” means (literally) “compare two(or more) and adjust” (and that is what Real s/w or h/w Load balancers do) but Browsers never do this, instead they randomly select and IP and connect to it. It doesn't have any knowledge about the current load of that server (probably, the IP it picked had the highest load!). Automatic failover (latest browsers only). Yes, I think DNS can be used as a simple failover system (at least in 2012, I dont know when it actually "came in effect"). please refer to : http://webmasters.stackexchange.com/questions/10927/using-multiple-a-records-for-my-domain-do-web-browsers-ever-try-more-than-one and Browser-based DNS failover using multiple A records and http://www.nber.org/sys-admin/dns-failover.html I would like to make sure my assumptions/findings are right. So let me know please.....

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  • How does one make sure or even guarantee server time are sync correctly between dozens of servers across multiple datacenter on different location?

    - by forestclown
    Currently our web applications contain a logic to check if the data sent to the web server is expired or not by comparing the timestamp of the data with the date/time of the server. Everything goes will, until some dude from data center accidentally modify one of the web server date/time and causes some disruptions in our web services. My managers are of course not happy with this, and said we shouldn't use timestamp to check expiry in the first place...anyway.... Network Time Protocol is implemented, because of data centers are spread across different continents so we have one NTP server in each data center. The servers within the data center will have cron jobs to check against the time with their NTP server from the same data center. If time is out of sync it will auto update the server date/time. But then with our managers not happy with it, and think it could still easily causes the same problem. e.g. what if someone accidentally modify the NTP date/time? what if all the NTP servers are out of sync with each other? which NTP servers we can really trust? and blah blah.. So my questions are: What are the current practice to sync date/time between servers across multiple data centers or locations? How does one manages time stamp between web apps? e.g. Server A send data (contain timestamp of Server A) to Server B (compare timestamp between Server B and the timestamp from the data to see if it has expired or not. This is to avoid HTTP replay) Should we really not use timestamp check? Thanks & Best Regards

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  • What precautions should I take once defective RAM has been replaced?

    - by DustByte
    I recently discovered that my RAM is faulty (MemTest86+). I am waiting for new RAM to be sent to me.  It was through sheer luck that I discovered something was wrong. I was copying a large amount of big files and decided to verify the copies by their checksums. I discovered strange discrepancies, and noticed that checksum computation for the same file was not consistent. Now, this is the only problem I have encountered; no BSOD, no crashes, no errors. In a sense this makes me more worried than if I would have had massive crashes. I have no idea for how long the RAM has been faulty, and I have no idea if corrupt bits have been saved into files on my hard drives. I do know the RAM was fine two months ago (tested it back then). I am a user of Adobe's Lightroom and I am worried that photos or the catalog itself could carry corrupt data. Question: what should I do once new healthy RAM has been installed? Reinstall Windows (I'm using Windows 7, 64 bit)? Is there a risk that I will be presented with nasty surprises in the future if I don't? What about personal files? I have backups of some of the files but for newer files I'm not sure I can even trust the backups. It's going to take me many hard hours to manually replace files with older versions, or compare checksums.

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