How to move primary shard from one server to another server

MongoDB University M103: Basic Cluster Administration
#1

Hi ,

I am working on chapter 3 and I have imported data in sharded cluster by connecting mongos.
i see it data is loaded and primary shard is “m103-repl-2”. but when i try to vailidate it is throwing error as below. Do i have to move primary shard to “m103-repl”
vagrant@m103:/shared/shard$ validate_lab_shard_collection

No documents found in m103.products - make sure you import the dataset into the
‘products’ collection in the ‘m103’ database.
vagrant@m103:/shared/shard$ validate_lab_shard_collection

Please find rs.status output.

=====================

MongoDB Enterprise mongos> sh.status()
— Sharding Status —
sharding version: {
“_id” : 1,
“minCompatibleVersion” : 5,
“currentVersion” : 6,
“clusterId” : ObjectId(“5c4922defe401b3b2410d221”)
}
shards:
{ “_id” : “m103-repl”, “host” : “m103-repl/192.168.103.100:27001,192.168.103.100:27002,192.168.103.100:27003”, “state” : 1 }
{ “_id” : “m103-repl-2”, “host” : “m103-repl-2/192.168.103.100:27004,192.168.103.100:27005,192.168.103.100:27006”, “state” : 1 }
active mongoses:
“3.6.9” : 2
autosplit:
Currently enabled: yes
balancer:
Currently enabled: yes
Currently running: no
Failed balancer rounds in last 5 attempts: 0
Migration Results for the last 24 hours:
1 : Success
databases:
{ “_id” : “config”, “primary” : “config”, “partitioned” : true }
config.system.sessions
shard key: { “_id” : 1 }
unique: false
balancing: true
chunks:
m103-repl 1
{ “_id” : { “$minKey” : 1 } } -->> { “_id” : { “$maxKey” : 1 } } on : m103-repl Timestamp(1, 0)
{ “_id” : “m103”, “primary” : “m103-repl-2”, “partitioned” : true }
m103.products
shard key: { “sku” : 1 }
unique: false
balancing: true
chunks:
m103-repl 1
m103-repl-2 2
{ “sku” : { “$minKey” : 1 } } -->> { “sku” : 23153496 } on : m103-repl Timestamp(2, 0)
{ “sku” : 23153496 } -->> { “sku” : 28928914 } on : m103-repl-2 Timestamp(2, 1)
{ “sku” : 28928914 } -->> { “sku” : { “$maxKey” : 1 } } on : m103-repl-2 Timestamp(1, 2)

#2

The error message you get is No documents found in m103.products - make sure you import the dataset into the ‘products’ collection in the ‘m103’ database.

Did you check how many documents you have? How many?

#3

Hi naseer561,

Yes it matters which is your primary shard as the Lab requires data to be present on primary shard i/e m103-repl and not m103-repl-2. Refer this link: movePrimary

And before sharding the collection make sure you have documents in the collection.

Kanika

#4

Thanks Kanikasingla,It helped. After moving to m103-repl it worked.

Thanks.
Regards,
Naseer.

#5

I tried this and DB is moved successfully but validation still failing
Any suggestions
Do we have to do any more steps after move
I even bounced all mongod still no resolution
Sharding collection was done on repl-2 before move
when i query sh.status() looks fine

2019-01-26T08:57:49.451+0000 [#######################.] m103.products 86.5MB/87.9MB (98.3%)
2019-01-26T08:57:50.940+0000 [########################] m103.products 87.9MB/87.9MB (100.0%)
2019-01-26T08:57:50.940+0000 imported 516784 documents
vagrant@m103:/dataset$ validate_lab_shard_collection

Incorrect number of documents imported - make sure you import the entire
dataset.
vagrant@m103:/dataset$ date
Sat Jan 26 09:33:13 UTC 2019
vagrant@m103:/dataset$ validate_lab_shard_collectioon

Incorrect number of documents imported - make sure you import the entire
dataset.
vagrant@m103:/dataset$ date
Sat Jan 26 09:59:37 UTC 2019
vagrant@m103:/dataset$

#6

it looks like records count is not matching with validate script. you need re-import the data by dropping m103 database and create shard key and make sure primary database is m103-repl.

than validate your script.

#7

Did you import products.json or products.part2.json?

#8

Shard key exists
all validations look fine
Not clear what all documents to be imported
I need to load just the one under /dataset or one attached in handouts or both
I tried all options .none worked

             { "_id" : { "$minKey" : 1 } } -->> { "_id" : { "$maxKey" : 1 } } on : m103-repl Timestamp(1, 0)
    {  "_id" : "m103",  "primary" : "m103-repl",  "partitioned" : true }
            m103.products
                    shard key: { "sku" : 1 }
                    unique: false
                    balancing: true
                    chunks:
                            m103-repl       1
                            m103-repl-2     2
                    { "sku" : { "$minKey" : 1 } } -->> { "sku" : 23153496 } on : m103-repl Timestamp(2, 0)
                    { "sku" : 23153496 } -->> { "sku" : 28928914 } on : m103-repl-2 Timestamp(2, 1)
                    { "sku" : 28928914 } -->> { "sku" : { "$maxKey" : 1 } } on : m103-repl-2 Timestamp(1, 2)
#9

can you count the record in you shard?

#10

Thanks for followup
Its completed
I repeated the steps from import
Went fine this time