What should we do if we have one tarantool instance (without Cartridge or VShard), then sometimes in the future we need to replicate it to another machine without downtime?
or if it's the easiest way is using cartridge, how to connect to tarantool cartridge from outside the cardridge? for example using golang (what's the username and password?):
taran, err = tarantool.Connect(cfg.Tarantool.Addr, tarantool.Opts{
User: cfg.Tarantool.User,
Pass: cfg.Tarantool.Pass,
Reconnect: 10 * time.Second,
MaxReconnects: 8640,
})
for example in other database only need to attach a new slave from the master (1 command line call) and wait for it to be sync (100% replicated).
Not sure I'll completely answer your question. But let's discuss every point separately.
Replication
You can use replication without vshard or cartridge. vshard is a module for sharding, if you don't need sharding you can use only replication feature.
Read about replication in documentation configuration - https://www.tarantool.io/en/doc/latest/book/replication/. Cartridge is just framework that simplifies cluster management and gives you huge amount of useful features.
User password
Also you ask about users/passwords. After you call box.cfg{listen=...} you could create some user, alter some rights for it and change its password. Please, read about user management in Tarantool in our documentation - https://www.tarantool.io/en/doc/latest/book/box/authentication/. After you create some user you can connect to Tarantool instance via connector, console (using tarantoolctl) or another Tarantool (using net.box module) under this user.
Talking about cartridge, it uses system user admin with cluster-cookie as a password.
Related
I'm looking into ways of replicating databases from On-Premise environments to Azure and one of the options I found was setting up a Read-Scale availability group.
The reason I'm using a Read-Scale and not an Always On availability group, is because I don't won't to use SQL Server Enterprise edition due to the cost.
I followed a tutorial from Microsoft (MS TUTORIAL) to set this all up and in the end, I think I got it working as my database appeared on the Azure environment.
However, the problem is that my replica always stays in the Synchronizing state - which is probably due to the fact I chose Asynchronous Replication by using the AVAILABILITY_MODE = ASYNCHRONOUS_COMMIT command - but even worse is that I can't access the database itself.
Each time I try to fire a query against it, it comes back with an Object is not accessible exception.
After some reading, I found that the cause of this might be because my replica doesn't have a secondary role. Trying to set this via the ... SECONDARY_ROLE({ALLOW_CONNECTIONS = ALL})... command, clearly states that this feature is not available in the Standard version of SQL Server.
My whole confusion comes from the fact that on the Microsoft documentation (MS DOCS), it says that With availability groups, one or more secondary replicas can be configured to support read-only access to secondary databases. which is exactly what I'm not succeeding in.
Did anybody have the same issue, or knows how to configure the Read-Scale availability group on SQL Server Standard so my second replica is accessible and readable as well?
P.S. I did look at the actual SQL Replication with Transaction Replication, but there are quite a bit of moving parts there, so I'm exploring all options before making a decision.
Based on a twitter conversation I found out that you will need to create a snapshot of the database in Secondary Replica in order to read from there.
Please read this tweeter thread.
I also added a suggestion in the feedback channel to fix the documentation.
I'm trying to launch ADF sample Session Management App that is provided in Oracle DOC.974949.1 , with EBS 12.2.6. I have done everything that is written in the Oracle doc. Still, session management is not working. When I start the EBS function responsible for launching sample app, I am redirected to EBS logon page. According to the use case from Oracle doc., it means that EBS user is not authenticated. I suspect that cookie which has session attributes cannot be correctly validated. Someone had that problem too? Could anyone suggest what should be done in order to launch the app?
Hard to know, but a couple things to check:
You need to be logged in via the standard EBS login
The EBS session cookies need to be scoped broadly enough to cover the new host
The DBC file associated with the Java SDK needs to be generated correctly
(see the Java SDK doc)
I want to disable the Database Replication from the replica cluster in MarkLogic 8 using ML-Gradle. After updating the configurations, I also want to re-enable it.
There are tasks for enabling and disabling flexrep in ML Gradle. But I couldn't found any such thing for Database Replication. How can this be done?
ml-gradle uses the Management API to handle configuration changes. Database Replication is controlled by sending a PUT command to /manage/v2/databases/[id-or-name]/properties. Update your ml-config/databases/content-database.json file (example that does not include that property) to include database-replication, including replication-enabled: true.
To see what that object should look like, you can send a GET request to the properties endpoint.
You can create your own command to set replication-enabled - see https://github.com/rjrudin/ml-gradle/wiki/Writing-your-own-management-task
I'll also add a ticket for making official commands - e.g. mlEnableReplication and mlDisableReplication, with those defaulting to the content database, and allowing for any database to be specified.
I am using redis for pub/sub as well as for server side cache. I mean my app server has redis server running as one process (functioning as a cache as well) . I have several thin clients (running redis client) connected to this app server in pub/sub mode. I would like to know where redis stores the cache data ? in server alone or there will be a copy in the clients as well. Also is it a good idea to use Redis in this fashion if there are close to 100 redis clients connected to server through pub/sub channel.
Thanks
Redis is a (sort of) in-memory noSQL database; but I found that my copy (running on linux) dumps to /var/lib/redis/dump.rdb
Redis can manage really big numbers of connections, by default its in-memory store (thanks to storing stuff in RAM it can be so fast).
But in the same time it can be configured as a persistent store, so dumping cached data (every x time or every x updated keys) to disk.
So it can be configured depending on your needs, have a look here.
All the cache data will be stored in the memory of the server provided to the config of running redis server.
The clients do not hold any data, they only access the data stored by the redis server.
I just installed redis on mac via homebrew. Without any configuration, I
found the dump.rdb is in my working directory (where I launched redis-server).
You can figure that out with the config command.
redis-cli config get dir
However as far as I know pub/sub data is volatile and not stored nor cached in redis at all. If you need that, you should look for a dedicated message broker like for example RabbitMQ.
On my Ubuntu, it was at /var/lib/redis/dump.rdb. On my macOS (installed via brew), it was at /usr/local/var/db/redis/dump.rdb.
Default location
/var/lib/redis/
Redis save all data in memory of server and rarely save date to disk.
For server<>client flow - all data transport with server.
Redis can processing number of clients ... default limit - 10.000
If you need less .. you must reconfigure OS, Server Settings etc. - http://redis.io/topics/clients
As I understood about the question your concern is about the Radis server memory and the client (application) memory.
I would like to know where redis stores the cache data ? in server alone or there will be a copy in the clients as well.
The Redis 6's client-side caching is what you actually looking for. There server and application both stores copies an keep in sync through a protocol communication. Eventhough they have implemented few ways to accomplish it following example (picked from the docs) mechanism will help you to understand it well.
Client 1 -> Server: CLIENT TRACKING ON
Client 1 -> Server: GET foo
(The server remembers that Client 1 may have the key "foo" cached)
(Client 1 may remember the value of "foo" inside its local memory)
Client 2 -> Server: SET foo SomeOtherValue
Server -> Client 1: INVALIDATE "foo"
Hope this helps. See that nice docs for more elaboration.
I have a web service that calls some stored procedure on a AS400 via JTOpen.
What I would like to do is that the connections used to call the stored procedures was opened in a specific subsystem with a specific user, instead of qusrwrk/quser as now (default).
I think I can be able to clone the qusrwrk subsystem to make it start with a specific user, but what I cannot figure out is the mechanism to open the connection in the specific subsystem.
I guess there should be a property at connection level to say subsystem=MySubsystem.
But unfortunatly I haven't found that property.
Any hint would be appreciated.
Flavio
Let the system take care of the subsystem the job database server job is started in.
You should just focus on the application (which is what IBM i excels in).
If need be, you can tweak subsystem parameters for QUSRWRK to improve performance by allocating memory, etc.
The system uses a pool of prestarted jobs as described in the FAQ: When I do WRKACTJOB, why is the host server job running under QUSER instead of the profile specified on the AS400 object?
To improve performance, the host server jobs are prestarted jobs running under QUSER. When the Toolbox connects to a host server job in order to perform an API call, run a command, etc, a request is sent from the Toolbox to an available prestarted job. This request includes the user profile specified on the AS400 object that represents the connection. The host server job receives the request and swaps to the specified user profile before it runs the request. The host server itself originally runs under the QUSER profile, so output from the WRKACTJOB command will show the job as being owned by QUSER. However, the job is in fact running under the profile specified on the request. To determine what profile is being used for any given host server job, you can do one of three things:
1. Display the job log for that job and find the message indicating which user profile is used as a result of the swap.
2. Work with the job and display job status attributes to view the current user profile.
3. Use Navigator for i to view all of the server jobs, which will list the current user of each job. You can also use Navigator for i to look at the server jobs being used by a particular user.