Mirroring

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In this post I show strategies for backing up Caché using External Backup with examples of integrating with snapshot based solutions. The majority of solutions I see today are deployed on Linux on VMware so a lot of the post shows how solutions integrate VMware snapshot technology as examples.

Last comment 30 September 2019
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I've created a scheduled task that dumps HL7 messages to flat files. It uses the OutputToLibraryStream() method of EnsLib.HL7.Message. I'd like to be able to run it on a mirror member host whether it's primary or backup.

When run against a database that's mounted read-only, it works fine. However, when I attempt to run it against a mirror backup database, I get the following error:

#5002: Cache error: <PROTECT>%LoadData+7^EnsLib.HL7.Message.1

Tracing that back to the source, I find:

Last answer 19 September 2019 Last comment 20 September 2019
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I'm trying to create a simple mirror with two Cachés 2016.2.1.803 Instances,

but after i create the mirror with the primary and try to connect the fallouver server, i receive the following message:

 

ERRO #2071: Erro ao recuperar informações do conjunto espelho para 'BPLUS'. Erro: Connection failed: Unexpected error: <READ>SSLServer+191^MIRRORCTL

i'm not using ssl on this configuration, tried with arbiter and without, same effect.

Tried with Caché 2018.1 and Caché 2016.2.1, same problem.

Some tips?

Best,

Last answer 13 September 2019
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Hi Community!

New video is already on InterSystems Developers YouTube Channel:

Making Cloud Deployments Cost Effective

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I've setup ODBC connection so I can access Cache data within SQL Server.

I want to be able to write SQL queries for internal monitoring purposes, similar to what's possible with SQL Server.  Specifically I want to be able to check mirroring status (i.e. check which is the current primary mirror member), check the status of any Ensemble productions (started/stopped), check the status of business hosts etc.  I want to do all of this from SQL Server to go with our other system monitoring solutions.

Last answer 1 August 2019
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I have a DR Mirror   with a WIJ that is 5 times as large as the Primary Failover member. My Read-Write Reporting mirror WIJs are the same size as the Primary.  I don't  know why the DR WIJ i so large and would like to shrink it to the same size as the others.  Any suggestions are welcome. Thanks!

Last answer 16 March 2019
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Hi guys

I've added a new mirrored failover member to an existing one.

They are both Arbiter controlled.

When I do Add database to mirror on the primary I'm always getting an error. Missing Mirrored database.

I followed everything in the documentation and always get the same error.

I've copied the CACHE.dat file after umounting the database on both servers. then mounted them.

Could you help me out?

 

Kind Regards

Last answer 4 March 2019
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InterSystems has corrected a defect that can result in data integrity problems in environments that use InterSystems mirroring in conjunction with parallel dejournaling. This problem exists for currently released Caché and Ensemble versions beginning with 2017.2 and for InterSystems IRIS Data Platform version 2018.1.

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Hi, would really appreciate your advice on how I can restart the mirror-monitor. I've followed the instructions and restarted the mirror monitor, and still the status seems to be down. Can you point me to some resource or steps that I can follow ?

I logged into %SYS terminal and restarted the mirror monitor and it says that it is running

Last answer 24 December 2018 Last comment 30 December 2018
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Mirroring 101

Caché mirroring is a reliable, inexpensive, and easy to implement high availability and disaster recovery solution for Caché and Ensemble-based applications. Mirroring provides automatic failover under a broad range of planned and unplanned outage scenarios, with application recovery time typically limited to seconds. Logical data replication eliminates storage as a single point of failure and a source of data corruption. Upgrades can be executed with little or no downtime.

Last comment 8 December 2018
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Hi All!

I asked previously about the DR server in the cloud but actually, I'm curious about the backup server to use as analytics server more than for recovery in DR case.

There is a recommended practice to use an async mirror as a server for BI (InterSystems Analytics, DeepSee)

The question is if I have PRIMARY in the cloud (AWS, Google, Azure, etc) "how far" should async mirror member be placed? Same cloud, same private cloud or it doesn't matter at all for analytics purposes?

Last answer 16 November 2018 Last comment 16 November 2018
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In this post, I am going to detail how to set up a mirror using SSL, including generating the certificates and keys via the Public Key Infrastructure built in to InterSystems IRIS Data Platform. I did a similar post in the past for Caché, so feel free to check that out here if you are not running InterSystems IRIS. Much like the original, the goal of this is to take you from new installations to a working mirror with SSL, including a primary, backup, and DR async member, along with a mirrored database. I will not go into security recommendations or restricting access to the files. This is meant to just simply get a mirror up and running. Example screenshots are taken on a 2018.1.1 version of IRIS, so yours may look slightly different.

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++ Update: August 1, 2018

The use of the InterSystems Virtual IP (VIP) address built-in to Caché database mirroring has certain limitations. In particular, it can only be used when mirror members reside the same network subnet. When multiple data centers are used, network subnets are not often “stretched” beyond the physical data center due to added network complexity (more detailed discussion here). For similar reasons, Virtual IP is often not usable when the database is hosted in the cloud.

Network traffic management appliances such as load balancers (physical or virtual) can be used to achieve the same level of transparency, presenting a single address to the client applications or devices. The network traffic manager automatically redirects clients to the current mirror primary’s real IP address. The automation is intended to meet the needs of both HA failover and DR promotion following a disaster. 

Last comment 14 June 2018
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In System Administration | Configuration |  System Configuration | Journal Settings there is a check box for Freeze on error.

From reading the documentation, it sounds like the choice to freeze on error is one of system availability vs system integrity.

Curious to know whether Ensemble users choose to freeze on error or not.

If you have a best practice recommendation based upon your experience or knowledge, that would be helpful information too.

Last answer 5 June 2018 Last comment 4 June 2018
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Hi

I'm using this query "Config.MapMirror.List" To get information of the list of servers that are in the mirror system.

I'd like to know how can I know which of the list is the primary and which is the failover or async member.

Is there a way to do it with this query? Is there another query to get this info?

Thanks a lot

Last answer 7 May 2018 Last comment 8 May 2018
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Hi, Community! 

 Check a new session recording from Global Summit 2017:

Mirror, Mirror, Which Should I Choose?

 

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I have Ensemble/Healthshare running in a production environment which is setup with a mirror failover and an arbiter sitting between them.

In the event of a failover we have a number of connections that need stopping/monitoring and starting in a certain order.

Is there a programmatic way we can detect the failover and stop certain services and operations immediately and then start them up again in the required order, checking their connection state before starting the next connection.

Last comment 10 November 2017
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Is it possible to make the cache terminal available over a mirrored vip address for a healthshare mirrored environment? So that connecting to a terminal for a mirrored environment will always connect to the Live Node?

 

I'm looking to write a Powershell script to run against the system and need to connect to the Live Node in a mirrored setup. Is this possible or am I going to have to log onto each node to establish which is Live.  Or does this even matter?

Last answer 1 November 2017 Last comment 6 November 2017
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Hi Community!

Please find the Developer Community Video of the week:

Failover for Cloud and Wide-Area Networks 

 

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Hi Community!

Please find the Developer Community video of the week on the InterSystems Developers YouTube Channel

Upgrades - Minimizing Business Disruption

 

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Hi All

I'm looking for some field experiences, lessons learned, or actual deployed solutions to the problem of replicating non-CACHE.DAT data in a mirrored Cache environment.  

Environment:

  • Operating System is IBM AIX
  • Hardware is IBM Power w/ virtualised storage
  • Cache 2017.1
  • 2x Production mirror members
  • 1x DR mirror member

 

There are a number of different data types that we're looking at mirroring, and a number of identified solutions.  The two main types of data to be mirrored outside of Cache mirroring are:

Last answer 22 May 2017
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