Which of these can be considered to monitor replication delay ? Redis_master_repl_offset, Redis_master_last_io_seconds_ago , Redis_slave_repl_offset
How do i measure redis replication delay
redisreplication
Related Solutions
Short answer - there's no such solution yet for PostgreSQL if you need online readonly slaves.
There're two major development projects currently going on in this area which are included in PostgreSQL 9.0 (Spring/Summer 2010), namely:
- Synchronous Replication:
http://wiki.postgresql.org/wiki/NTT's_Development_Projects
- Read only hot standby slaves:
http://wiki.postgresql.org/wiki/Hot_Standby
which in combination aim to achieve the ease of use of MySQL-style replication minus the bugs/issues MySQL has plus the reliability users know from PostgreSQL.
All of this was kicked off by a manifest from the PostgreSQL Core Team in 2008:
http://archives.postgresql.org/pgsql-hackers/2008-05/msg00913.php
The PostgreSQL replication solutions to this day with the largest user base are Slony-I (more expensive for writes, makes schema changes fiddly), WAL shipping/walmgr (Slaves can't be used online) and pgQ/londiste from Skype/Skytools (more tools/building blocks than a finished solution).
I've written a few things on Log Shipping, walmgr and Slony-I, see
http://blogs.amd.co.at/mt/mt-search.cgi?blog_id=1&tag=pgrep&limit=20 for more information.
Perhaps a little presumptuous of me to merely post the help file but in short, it's the answer you're after.
Also look at dcdiag.exe for other information regarding DNS since replication relies heavily on your DNS infrastructure being fully operational.
C:\repadmin.exe /?
Usage: repadmin <cmd> <args> [/u:{domain\user}] [/pw:{password|*}]
[/retry[:<retries>][:<delay>]]
[/csv]
Use these commands to see the help:
/? Displays a list of commands available for use in repadmin and their
description.
/help Same as /?
/?:<cmd> Displays the list of possible arguments <args>, appropriate
syntaxes and examples for the specified command <cmd>.
/help:<cmd> Same as /?:<cmd>
/experthelp Displays a list of commands for use by advanced users only.
/listhelp Displays the variations of syntax available for the DSA_NAME,
DSA_LIST, NCNAME and OBJ_LIST strings.
/oldhelp Displays a list of deprecated commands that still work but
are no longer supported by Microsoft.
Supported <cmd> commands (use /?<cmd> for detailed help):
/kcc Forces the KCC on targeted domain controller(s) to immediately
recalculate its inbound replication topology.
/prp This command allows an admin to view or modify the
password replication policy for RODCs.
/queue Displays inbound replication requests that the DC needs to issue
to become consistent with its source replication partners.
/replicate Triggers the immediate replication of the specified directory
partition to the destination domain controller from the source DC.
/replsingleobj Replicates a single object between any two domain
controllers that have common directory partitions.
/replsummary The replsummary operation quickly and concisely summarizes
the replication state and relative health of a forest.
/rodcpwdrepl Triggers replication of passwords for the specified user(s)
from the source (Hub DC) to one or more Read Only DC's.
/showattr Displays the attributes of an object.
/showobjmeta Displays the replication metadata for a specified object
stored in Active Directory, such as attribute ID, version
number, originating and local Update Sequence Number (USN), and
originating server's GUID and Date and Time stamp.
/showrepl Displays the replication status when specified domain controller
last attempted to inbound replicate Active Directory partitions.
/showutdvec displays the highest committed Update Sequence Number (USN)
that the targeted DC's copy of Active Directory shows as
committed for itself and its transitive partners.
/syncall Synchronizes a specified domain controller with all replication
partners.
Supported additional parameters:
/u: Specifies the domain and user name separated by a backslash
{domain\user} that has permissions to perform operations in
Active Directory. UPN logons not supported.
/pw: Specifies the password for the user name entered with the /u
parameter.
/retry This parameter will cause repadmin to repeat its attempt to bind
to the target dc should the first attempt fail with one of the
following error status:
1722 / 0x6ba : "The RPC Server is unavailable"
1753 / 0x6d9 : "There are no more endpoints available from the
endpoint mapper"
/csv Used with /showrepl to output results in comma separated
value format. See /csvhelp
Note: Most commands take their parameters in the order of "Destination or
Target DSA_LIST", then a "Source DSA_NAME" if required, and finally the
NC or Object DN if required.
<DSA_NAME> (or <DSA_LIST>) is a Directory Service Agent binding
string. For Active Directory Domain Services, this is simply a network
label (such as a DNS, NetBios, or IP address) of a Domain Controller.
For Active Directory Lightweight Directory Services, this must be a
network label of the AD LDS server followed by a colon and the LDAP
port of the AD LDS instance
Examples (AD DS): dc-01
dc-01.microsoft.com
Examples (AD LDS): ad-am-01:2000
ad-am-01.microsoft.com:2000
<Naming Context> is the Distinguished Name of the root of the NC
Example: DC=My-Domain,DC=Microsoft,DC=Com
Note: Text (Naming Context names, server names, etc) with International or
Unicode characters will only display correctly if appropriate fonts and
language support are loaded.
Best Answer
Given results from an
INFO replicationcommand like this:You can tell that
slave0is behind master by 6. This is the difference between themaster_repl_offsetand the offset value in theslave0line, which is the last number in it. If you have multiple slaves, each will get their own line with their own offset value.