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  • How to organize integrity tests and code unit tests?

    - by karlthorwald
    I have several files with code testing code (which uses a "unittest" class). Later I found it would be nice to test database integrity also. I put this into a separate directory tree. (Things like the keys have correct format, parent and child nodes are pointing correctly and such.) I use the same unittest class for the integrity tests. Now I wonder if it makes really sense to keep this separate. To test the integrity of data I often duplicate parts of code that I use to test the code that handles the data. But it is not the same. The code tests use test databases (that get deleted after each test) and the integrity tests connect to the live data and analyze it. The integrity tests I want to call from cron and send an alarm if something happens in the live database. How would you handle that? Are there standards for such a setup? What is your experience? My tendency is to put everything in the same file, which would result in the code tests also being executed by the cron on the production environment.

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  • How to organize live data integrity tests and code unit tests?

    - by karlthorwald
    I have several files with code testing code (which uses a "unittest" class). Later I found it would be nice to test database integrity also. I put this into a separate directory tree. (Things like the keys have correct format, parent and child nodes are pointing correctly and such.) I use the same unittest class for the integrity tests. Now I wonder if it makes really sense to keep this separate. To test the integrity of data I often duplicate parts of code that I use to test the code that handles the data. But it is not the same. The code tests use test databases (that get deleted after each test) and the integrity tests connect to the live data and analyze it. The integrity tests I want to call from cron and send an alarm if something happens in the live database. How would you handle that? Are there standards for such a setup? What is your experience? My tendency is to put everything in the same file, which would result in the code tests also being executed by the cron on the production environment.

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  • No apparent reason for high load average

    - by Oz.
    We have several web servers running on Amazon (ec2) c1.xlarge, over Amazon AMI. The servers are duplicates of each other, running the exact same hardware and software. Each server spec is: 7 GB of memory 20 EC2 Compute Units (8 virtual cores with 2.5 EC2 Compute Units each) 1690 GB of instance storage 64-bit platform I/O Performance: High API name: c1.xlarge A couple of weeks ago we have run a yum upgrade on one of the servers. Starting on this upgrade the upgraded server started showing a high load average. Needless to say, we did not update the other servers and we can not do so until we understand the reason for this behavior. The strange thing is that when we compare the servers using top or iostat, we can not find the reason for the high load. Note that we have moved traffic from the "problematic" server to the others, which have made the "problematic" server less crowded in terms of requests, and still his load is higher. Do you have any idea what could it be, or where else can we check? Many thanks for the help! Oz. # # proper server # w command # 00:42:26 up 2 days, 19:54, 2 users, load average: 0.41, 0.48, 0.49 USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT pts/1 82.80.137.29 00:28 14:05 0.01s 0.01s -bash pts/2 82.80.137.29 00:38 0.00s 0.02s 0.00s w # # proper server # iostat command # Linux 3.2.12-3.2.4.amzn1.x86_64 _x86_64_ (8 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 9.03 0.02 4.26 0.17 0.13 86.39 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn xvdap1 1.63 1.50 55.00 367236 13444008 xvdfp1 4.41 45.93 70.48 11227226 17228552 xvdfp2 2.61 2.01 59.81 491890 14620104 xvdfp3 8.16 14.47 94.23 3536522 23034376 xvdfp4 0.98 0.79 45.86 192818 11209784 # # problematic server # w command # 00:43:26 up 2 days, 21:52, 2 users, load average: 1.35, 1.10, 1.17 USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT pts/0 82.80.137.29 00:28 15:04 0.02s 0.02s -bash pts/1 82.80.137.29 00:38 0.00s 0.05s 0.00s w # # problematic server # iostat command # Linux 3.2.20-1.29.6.amzn1.x86_64 _x86_64_ (8 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 7.97 0.04 3.43 0.19 0.07 88.30 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn xvdap1 2.10 1.49 76.54 374660 19253592 xvdfp1 5.64 40.98 85.92 10308946 21612112 xvdfp2 3.97 4.32 93.18 1087090 23439488 xvdfp3 10.87 30.30 115.14 7622474 28961720 xvdfp4 1.12 0.28 65.54 71034 16487112

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  • High quality / high speed dvd reader for Mac Pro

    - by deadprogrammer
    I have a high end Mac pro, but one thing in is that I'm unhappy with is a DVD drive. It's a Hitachi GH41N. Apple calls it a "superdrive", but it's anything but. The damn thing makes an amazing amount of noise, and isn't too fast either. What I want is a state of the art, fast, quiet DVD reader, preferably not even a burner. What should I get?

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  • High server load - [jbd2/md1-8] using 99.99% IO

    - by Alex
    I've been having spike in load over the last week. This usually occurs once or twice a day. I've managed to identify from iotop that [jbd2/md1-8] is using 99.99 % IO. During the high load times there is no high traffic to the server. Server specs are: AMD Opteron 8 core 16 GB RAM 2x2.000 GB 7.200 RPM HDD Software Raid 1 Cloudlinux + Cpanel Mysql is properly tuned Apart from the spikes, the load usually is around 0.80 at most. I've searched around but can't find what [jbd2/md1-8] does exactly. Has anyone had this problem or does anyone know a possible solution? Thank you. UPDATE: TIME TID PRIO USER DISK READ DISK WRITE SWAPIN IO COMMAND 16:05:36 399 be/3 root 0.00 B/s 38.76 K/s 0.00 % 99.99 % [jbd2/md1-8]

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  • Cheapest High Available Web Server [closed]

    - by xyz
    I would like to create a high-available setup (e.g. a small cluster) for a webserver, i.e. it will run Apache, PHP and MySQL. There will be between 2-8 small websites running with only very little traffic and workload. High availability is however very important. I don't want to be dependent on 1 datacenter, so there must be a minimum of 2 servers placed in different datacenters, and if one server goes down, the user must experience no or only a minimum of downtime - and no data loss. I have considered Amazon AWS using their Elastic Load Balancing, since it is possible to buy 2 EC2 instances in 2 availability zones and set up load balancing and RDS (Multi-AZ). However this seems rather expensive. Using the AWS price calculator http://calculator.s3.amazonaws.com/calc5.html it totals to 185$/month the first year (including the free tier). Are my calculations incorrect or is there a cheaper way to make this HA setup? Best regards

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  • How to setup Wordpress High Availability

    - by Ketam
    I have installed Galera Cluster on 3 cluster + 1 management. I wanted to make it like this, Server1: Home (www.domain.com) Server2: For BBpress/Forum (Forum Tab Menu will forward to forum.domain.com) Server3: BuddyPress Activity (Social Tab Menu will forward to social.domain.com) The purpose I am doing this is to distribute my resource and load balancing each other at same time. However, I have difficulty to setup Apache Load-Balancing/mod_proxy/clustering or any suitable to have high availability WordPress. Any best suggestion/solution to make high availability WordPress? Or how to? And another question is I tried to copy whole WordPress files & folders to Server2 connecting to local database (same data inside since it is already on Galera Cluster) but the page blank. Any advice? OS: Centos 6.2 Thanks in advanced.

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  • Why isn't SSL/TLS built into modern Operating Systems?

    - by Channel72
    A lot of the basic network protocols that make up the infrastructure of the Internet are built in to most major Operating Systems. Things like TCP, UDP, and DNS are all built into Linux, UNIX and Windows, and are made available to the programmer through low-level system APIs. But when it comes to SSL or TLS, one has to turn to a third-party library such as OpenSSL or Mozilla NSS. SSL is a relatively old protocol, and it's basically an industry standard as ubiquitous as TCP/IP, so why isn't it built into most Operating Systems?

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  • No clue for high load average on top

    - by Oz.
    We have several machines on Amazon (ec2) of the type c1.xlarge with 16 cpus, running the Amazon AMI. Details on the machine: 7 GB of memory 20 EC2 Compute Units (8 virtual cores with 2.5 EC2 Compute Units each) 1690 GB of instance storage 64-bit platform I/O Performance: High API name: c1.xlarge One out of the several machines is showing a high load average, since we have run the last yum upgrade a couple of weeks a go. We did not yet update the other machines, and everything looks normal on them. The strange thing is that the top command not showing any hint for the cause of the load. CPUs are 4.8%us, 1.1%sy, 0.0%ni, 94.1%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st(see below). Mem is about 1.5GB free. Any idea what could it be, or where else can we check? Many thanks for the help. # # top # top - 07:57:42 up 4:18, 1 user, load average: 1.36, 1.45, 1.47 Tasks: 131 total, 1 running, 130 sleeping, 0 stopped, 0 zombie Cpu(s): 4.8%us, 1.1%sy, 0.0%ni, 94.1%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 7120092k total, 5644920k used, 1475172k free, 532888k buffers Swap: 0k total, 0k used, 0k free, 3463936k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1557 mysql 20 0 1829m 374m 6448 S 14.3 5.4 11:15.09 mysqld 6655 apache 20 0 416m 49m 3744 S 9.3 0.7 0:04.85 httpd 27683 apache 20 0 421m 54m 3708 S 9.0 0.8 0:00.99 httpd 6682 apache 20 0 424m 57m 3788 S 8.3 0.8 0:03.81 httpd 16816 apache 20 0 419m 51m 3760 S 4.3 0.7 0:04.09 httpd 22182 apache 20 0 417m 50m 3756 S 1.7 0.7 0:06.34 httpd 219 root 20 0 0 0 0 S 0.3 0.0 0:00.34 kworker/7:1 699 root 20 0 0 0 0 S 0.3 0.0 0:00.40 kworker/3:1 1 root 20 0 19376 1508 1212 S 0.0 0.0 0:00.29 init 2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd 3 root 20 0 0 0 0 S 0.0 0.0 0:00.71 ksoftirqd/0

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  • What route to take to become a systems developer?

    - by Ramin
    In the past I have done a lot of Java and Python coding. Mostly, I worked on web apps and some simple console or gui apps. I also have a formal education in computer science. What route should I take to become a systems developer? I always did like C++, but never had a chance to use it for anything. Would mastering C++ be one of the steps? If so what resources can you suggest? Also, I would like to know how much different is the work between plain old development and systems development. There seem to be a lot of overlapping between the two.

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  • Prevent two users from editing the same data

    - by Industrial
    Hi everyone, I have seen a feature in different web applications including Wordpress (not sure?) that warns a user if he/she opens an article/post/page/whatever from the database, while someone else is editing the same data simultaneously. I would like to implement the same feature in my own application and I have given this a bit of thought. Is the following example a good practice on how to do this? It goes a little something like this: 1) User A enters a the editing page for the mysterious article X. The database tableEvents is queried to make sure that no one else is editing the same page for the moment, which no one is by then. A token is then randomly being generated and is inserted into a database table called Events. 1) User B also want's to make updates to the article X. Now since our User A already is editing the article, the Events table is queried and looks like this: | timestamp | owner | Origin | token | ------------------------------------------------------------ | 1273226321 | User A | article-x | uniqueid## | 2) The timestamp is being checked. If it's valid and less than say 100 seconds old, a message appears and the user cannot make any changes to the requested article X: Warning: User A is currently working with this article. In the meantime, editing cannot be done. Please do something else with your life. 3) If User A decides to go on and save his changes, the token is posted along with all other data to update the database, and toggles a query to delete the row with token uniqueid##. If he decides to do something else instead of committing his changes, the article X will still be available for editing in 100 seconds for User B Let me know what you think about this approach! Wish everyone a great weekend!

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  • Introduction to Lean Software Development and Kanban Systems – Build Integrity and Quality In

    - by Ben Griswold
    In this post, we’ll continue the series by concentrating on Principle #3: Build Integrity and Quality In.   In the next part of the series, we’ll dive into Principle #4: Defer Commitment and Decide As Late As Possible. And I am going to be a little obnoxious about listing my Lean and Kanban references with every series post.  The references are great and they deserve this sort of attention.  

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  • Referential Integrity: Best Practices for IBM DB2

    Of the various constraints possible on relational tables, referential constraints are perhaps the most common ... and most misused. Learn about the advantages and disadvantages of different methods to implement and enforce RI, and issues that must be addressed when implementing DBMS-enforced Referential Integrity.

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  • Sets, Surrogates, Normalisation, Referential Integrity - the Theory with example Scaling considerati

    - by tonyrogerson
    The Slides and Demo's for the SQLBits session I did today at SQL Bits in London are attached. The Agenda was... Thinking in Sets Surrogate Keys ú What they are ú Comparison NEWID, NEWSEQUENTIALID, IDENTITY ú Fragmenation Normalisation ú An introduction – what is it? Why use it? ú Joins – Pre-filter problems, index intersection ú Fragmentation again Referential Integrity ú Optimiser -> Query rewrite ú Locking considerations around Foreign Keys and Declarative RI (using Triggers)...(read more)

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  • Choice of operating systems for a Rackspace cloud installation

    - by riteshmnayak
    I am planning to use Rackspace cloud services to host a java web application and also run apace for wordpress and trac. What would be a stable operating system to host such an application. My requirements are that the core OS bundle should be minimalistic (so I can install only what I want), consume very little memory and be performant. I would also need it to contain softwares for the common lamp stack, J2EE stack etc. A supported package manager would be lovely. My choices are listed below. RHEL 5.3 or 5.4 Debian Lenny Ubuntu 8.04 onwards Centos 5.3 or 5.4 Arch 2009.02 Gentoo 2008.0 or 10.1 Fedora 11 or 12 PS: can somebody add the rackspace tag to this? Edit to remove this line as well. Thanks

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  • High CPU from httpd process

    - by KHWeb
    I am currently getting high CPU on a server that is just running a couple of sites with very low traffic. One of the sites is in still development going live soon. However, this site is very very slow...When browsing through its pages I can see that the CPU goes from 30% to 100% for httpd (see top output below). I have tuned httpd & MySQL, Apache Solr, Tomcat for high performance, and I am using APC. Not sure what to do from here or how to find the culprit as I have a bunch of messages on the httpd log and have been chasing dead ends for some time...any help is greatly appreciated. Server: AuthenticAMD, Quad-Core AMD Opteron(tm) Processor 2352, RAM 16GB Linux 2.6.27 64-bit, Centos 5.5 Plesk 9.5.4, MySQL 5.1.48, PHP 5.2.17 Apache/2.2.3 (CentOS) DAV/2 mod_jk/1.2.15 mod_ssl/2.2.3 OpenSSL/0.9.8e-fips-rhel5 PHP/5.2.17 mod_perl/2.0.4 Perl/v5.8.8 Tomcat6-6.0.29-1.jpp5, Tomcat-native-1.1.20-1.el5, Apache Solr top 17595 apache 20 0 1825m 507m 10m R 100.4 3.2 0:17.50 httpd 17596 apache 20 0 1565m 247m 9936 R 83.1 1.5 0:10.86 httpd 17598 apache 20 0 1430m 110m 6472 S 54.5 0.7 0:08.66 httpd 17599 apache 20 0 1438m 124m 12m S 37.2 0.8 0:11.20 httpd 16197 mysql 20 0 13.0g 2.0g 5440 S 9.6 12.6 297:12.79 mysqld 17617 root 20 0 12748 1172 812 R 0.7 0.0 0:00.88 top 8169 tomcat 20 0 4613m 268m 6056 S 0.3 1.7 6:40.56 java httpd error_log [debug] prefork.c(991): AcceptMutex: sysvsem (default: sysvsem) [info] mod_fcgid: Process manager 17593 started [debug] proxy_util.c(1854): proxy: grabbed scoreboard slot 0 in child 17594 for worker proxy:reverse [debug] proxy_util.c(1967): proxy: initialized single connection worker 0 in child 17594 for (*) [debug] proxy_util.c(1854): proxy: grabbed scoreboard slot 0 in child 17595 for worker proxy:reverse [debug] proxy_util.c(1873): proxy: worker proxy:reverse already initialized [notice] child pid 22782 exit signal Segmentation fault (11) [error] (43)Identifier removed: apr_global_mutex_lock(jk_log_lock) failed [debug] util_ldap.c(2021): LDAP merging Shared Cache conf: shm=0x7fd29a5478c0 rmm=0x7fd29a547918 for VHOST: example.com [info] APR LDAP: Built with OpenLDAP LDAP SDK [info] LDAP: SSL support available [info] Init: Seeding PRNG with 256 bytes of entropy [info] Init: Generating temporary RSA private keys (512/1024 bits) [info] Init: Generating temporary DH parameters (512/1024 bits) [debug] ssl_scache_shmcb.c(374): shmcb_init allocated 512000 bytes of shared memory [debug] ssl_scache_shmcb.c(554): entered shmcb_init_memory() [debug] ssl_scache_shmcb.c(576): for 512000 bytes, recommending 4265 indexes [debug] ssl_scache_shmcb.c(619): shmcb_init_memory choices follow [debug] ssl_scache_shmcb.c(621): division_mask = 0x1F [debug] ssl_scache_shmcb.c(623): division_offset = 96 [debug] ssl_scache_shmcb.c(625): division_size = 15997 [debug] ssl_scache_shmcb.c(627): queue_size = 2136 [debug] ssl_scache_shmcb.c(629): index_num = 133 [debug] ssl_scache_shmcb.c(631): index_offset = 8 [debug] ssl_scache_shmcb.c(633): index_size = 16 [debug] ssl_scache_shmcb.c(635): cache_data_offset = 8 [debug] ssl_scache_shmcb.c(637): cache_data_size = 13853 [debug] ssl_scache_shmcb.c(650): leaving shmcb_init_memory()

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  • High Availability with 2 servers?

    - by Tom R
    Is it possible to have a high availability setup with 2 servers? Running Windows Web Server 2008 and MSSQL Web Edition (as I know Express isn't supported)? Getting to the point where our one dedicated server needs scaled out and going to a second server already more than doubles the cost as need to use Web Edition rather than Express (db is only 500MB).

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  • What hash should be used to ensure file integrity?

    - by Corey Ogburn
    It's no secret that large files offered up for download often are coupled with their MD5 or SHA-1 hash so that after you download you can verify the file's integrity. Are these still the best algorithms to use for this? Obviously these are very popular hashes that potential downloaders would have easy access to. Ignoring that factor, what hashes have the best properties for being used for this? For example, bcrypt would be horrible for this. It's designed to be slow. That would suck to use on your 7.4 GB dual layer OS ISO you just downloaded when a 12 letter password might take up to a second with the right parameters.

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  • high resolution on small screen size

    - by vishesh
    I have recently got an intel ultrabook,but its screen size is 13.3' and the native resolution is 1600X900.So the problem is that the letters that appear on screen are very small.Reducing resolution blurs the display and making everything bigger also doesn't feel very good.is there a way to get around this problem without changing hardware. I am even ok with this high resolution but I am concerned about the harmful effects it might have on my eyes in long term. Any advice will be very useful.Please help

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  • GlusterFs - high load 90-107% CPU

    - by Sara
    I try and try and try to performance and fix problem with gluster, i try all. I served on gluster webpages, php files, images etc. I have problem after update from 3.3.0 to 3.3.1. I try 3.4 when i think maybe fix it but still the same problem. I temporarily have 1 brick, but before upgrade will be fine. Config: Volume Name: ... Type: Replicate Volume ID: ... Status: Started Number of Bricks: 0 x 2 = 1 Transport-type: tcp Bricks: Brick1: ...:/... Options Reconfigured: cluster.stripe-block-size: 128KB performance.cache-max-file-size: 100MB performance.flush-behind: on performance.io-thread-count: 16 performance.cache-size: 256MB auth.allow: ... performance.cache-refresh-timeout: 5 performance.write-behind-window-size: 1024MB I use fuse, hmm "Maybe the high load is due to the unavailable brick" i think about it, but i cant find information on how to safely change type of volume. Maybe u know how?

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  • Providing high availability and failover using MySQL on EC2

    - by crb
    I would like to have a highly-available MySQL system, with automatic failover, running on Amazon EC2 instances. The standard approach to solving this is problem Heartbeat + DRBD, but I've found a lot of posts suggesting DRBD doesn't work on EC2, though none saying exactly why. Obviously, a serial heartbeat or distinct network is out of the question in the virtualised environment. It would also be good to have the different servers be in different availability zones, but we're getting into a much harder problem there. What are peoples' opinion on having a high uptime solution in "the cloud"?

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  • Most suitable high availability solution

    - by Alex Bagnolini
    My company is hosting a website in a server with IIS, SQL Server and a 3rd party windows service (written in C#, source code available for amendments). We bought a new identical server, composed by: 1x Quad Core, 12GB RAM, 4x160GB SATA Raid 5, Windows Server 2008 R2 Datacenter, Public IP. We aim to put all webpages and the 3rd party windows service in an high-availability state. After some lab-testing on how to configure Failover Clustering and Hyper-V, we have deep doubts on what the "best" solution would be, by "best" meaning maintainable and able to correctly handle a physical server failure. Any suggestion on how we should configure the two servers? We don't need all the configuration's step, just an hint on the right direction to follow.

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  • Unable to watch a high resolution and high frame rate video

    - by Abhijith Madhav
    I have a video of a tennis match whose Resolution = 1280 * 720 Codec = H264 Frame rate = 50fps (Copy paste from info given by totem media player) My laptop is not powerful enough to play this video smoothly. How can I reduce the frame-rate of this video so that my laptop can play it? I have observed that my laptop can play videos with 25fps without an issue. I use ubuntu. I wouldn't mind using windows to edit/re-encode this video.

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  • VMware Virtual vCenter and High Availability

    - by rufo
    To continue with this question: Should be Vmware vCenter server high available? According to the response there even if vCenter is down HA will continue to work. So, if my vCenter is a VM, using the express sql edition in the same VM, and that VM is hosted in the same cluster it manages (and the cluster is setup for HA): Am I correct to assume that if the host that hosts the vCenter goes down HA will vmotion the vCenter VM to another host and it will continue to function? BTW: my environment is small, two ESXi 5.0 hosts, with about 50 VMs, using iSCSI shared storaged for everything.

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