add backup restore postgresql using zfs snapshot
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content/post/postgresql-backup-restore-using-zfs-snapshot.md
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content/post/postgresql-backup-restore-using-zfs-snapshot.md
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title: "[筆記] 用zfs的snapshot 快照功能來做 postgresql 的備份還原 / Postgresql Backup Restore Using Zfs Snapshot"
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date: 2019-09-06T10:42:11+08:00
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noSummary: false
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featuredImage: "https://h.cowbay.org/images/post-default-5.jpg"
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categories: ['筆記']
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tags: ['postgresql','zfs','backup','restore']
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author: "Eric Chang"
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keywords:
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- postgresql
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- zfs
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- backup
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- restore
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---
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前面測試了用pgbarman / pgbackrest 來備份 postgresql
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這次改從system file level 來下手
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採用zfs 的快照來備份、還原postgresql 資料庫
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<!--more-->
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### 建立測試資料庫、TABLE、snapshot
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#### 資料庫現況
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只有系統預設的DB，沒有其他多的東西
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```
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postgres@hqdc034:~$ psql -c '\l'
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List of databases
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Name | Owner | Encoding | Collate | Ctype | Access privileges
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-----------+----------+----------+-------------+-------------+-----------------------
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postgres | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
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template0 | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/postgres +
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| | | | | postgres=CTc/postgres
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template1 | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/postgres +
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| | | | | postgres=CTc/postgres
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(3 rows)
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postgres@hqdc034:~$ du -sh /zp/database/10/main/
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232M /zp/database/10/main/
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```
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#### 建立第一次的快照
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```
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2019-09-06 09:03:46 [changch@hqdc034 ~]$ sudo zfs list -t snapshot
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no datasets available
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2019-09-06 09:03:53 [changch@hqdc034 ~]$ sudo zfs snapshot zp/database@init_db_no_demo
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2019-09-06 09:04:09 [changch@hqdc034 ~]$ sudo zfs list -t snapshot
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NAME USED AVAIL REFER MOUNTPOINT
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zp/database@init_db_no_demo 0 - 231M -
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2019-09-06 09:04:15 [changch@hqdc034 ~]$
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```
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#### 建立、倒回測試資料庫 demo
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```
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postgres@hqdc034:~$ createdb demo
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postgres@hqdc034:~$ psql demo < /home/changch/Downloads/demo.sql
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SET
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SET
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略...
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```
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再檢查一次資料庫的狀況，看到 demo DB出現了，資料庫目錄也變大了
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```
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postgres@hqdc034:~$ psql -c '\l'
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List of databases
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Name | Owner | Encoding | Collate | Ctype | Access privileges
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-----------+----------+----------+-------------+-------------+-----------------------
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demo | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
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postgres | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
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template0 | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/postgres +
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| | | | | postgres=CTc/postgres
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template1 | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/postgres +
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| | | | | postgres=CTc/postgres
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(4 rows)
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postgres@hqdc034:~$ du -sh /zp/database/10/main/
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2.1G /zp/database/10/main/
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postgres@hqdc034:~$
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```
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#### 建立第二次快照
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這次的快照，將包含剛剛倒回的 demo DB，但是不包含等下才要建立的測試 table
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```
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2019-09-06 09:16:01 [changch@hqdc034 ~]$ sudo zfs list -t snapshot
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NAME USED AVAIL REFER MOUNTPOINT
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zp/database@init_db_no_demo 250K - 231M -
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zp/database@demo_db_just_restore 0 - 2.08G -
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2019-09-06 09:16:04 [changch@hqdc034 ~]$
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```
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#### 建立測試 table
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```
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postgres@hqdc034:~$ psql -c 'create table test ( a int, b varchar(50) );'
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CREATE TABLE
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postgres@hqdc034:~$
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```
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#### 建立第三次快照
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這次快照，只有建立 test table ，但是裡面沒有資料
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```
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2019-09-06 09:18:34 [changch@hqdc034 ~]$ sudo zfs list -t snapshot
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NAME USED AVAIL REFER MOUNTPOINT
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zp/database@init_db_no_demo 250K - 231M -
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zp/database@demo_db_just_restore 138K - 2.08G -
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zp/database@demo_db_create_test_table_but_no_data 0 - 2.08G -
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2019-09-06 09:18:36 [changch@hqdc034 ~]$
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```
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#### 在test table 插入100萬筆資料
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```
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postgres@hqdc034:~$ psql -c 'with aa as ( select * from generate_series (1,1000000) a ) insert into test select aa.a, md5(aa.a::varchar) from aa;'
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INSERT 0 1000000
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postgres@hqdc034:~$ psql -c 'select count(*) from test;'
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count
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---------
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1000000
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(1 row)
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postgres@hqdc034:~$
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```
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#### 建立第四次快照
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test table 內有 1000000 筆資料
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```
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2019-09-06 09:18:36 [changch@hqdc034 ~]$ sudo zfs snapshot zp/database@demo_db_test_table_with_1M_rows
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2019-09-06 09:21:08 [changch@hqdc034 ~]$ sudo zfs list -t snapshot
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NAME USED AVAIL REFER MOUNTPOINT
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zp/database@init_db_no_demo 250K - 231M -
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zp/database@demo_db_just_restore 138K - 2.08G -
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zp/database@demo_db_create_test_table_but_no_data 116K - 2.08G -
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zp/database@demo_db_test_table_with_1M_rows 0 - 2.15G -
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2019-09-06 09:21:09 [changch@hqdc034 ~]$
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```
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#### 再次插入 100萬筆資料
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```
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postgres@hqdc034:~$ time psql -c 'with aa as ( select * from generate_series (1,1000000) a ) insert into test select aa.a, md5(aa.a::varchar) from aa;'
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INSERT 0 1000000
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real 0m4.276s
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user 0m0.020s
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sys 0m0.012s
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postgres@hqdc034:~$ psql -c 'select count(*) from test;'
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count
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---------
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2000000
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(1 row)
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postgres@hqdc034:~$
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```
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#### 建立第五次快照
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現在 test table 有 200萬筆資料了
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```
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2019-09-06 09:21:09 [changch@hqdc034 ~]$ sudo zfs snapshot zp/database@demo_db_test_table_with_2M_rows
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2019-09-06 09:22:29 [changch@hqdc034 ~]$ sudo zfs list -t snapshot
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NAME USED AVAIL REFER MOUNTPOINT
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zp/database@init_db_no_demo 250K - 231M -
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zp/database@demo_db_just_restore 138K - 2.08G -
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zp/database@demo_db_create_test_table_but_no_data 116K - 2.08G -
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zp/database@demo_db_test_table_with_1M_rows 218K - 2.15G -
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zp/database@demo_db_test_table_with_2M_rows 0 - 2.23G -
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2019-09-06 09:22:30 [changch@hqdc034 ~]$
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```
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#### 玩大點，直接湊滿1000萬筆資料好了
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```
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postgres@hqdc034:~$ time psql -c 'with aa as ( select * from generate_series (1,8000000) a ) insert into test select aa.a, md5(aa.a::varchar) from aa;'
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INSERT 0 8000000
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real 0m32.172s
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user 0m0.024s
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sys 0m0.008s
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postgres@hqdc034:~$ psql -c 'select count(*) from test;'
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count
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----------
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10000000
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(1 row)
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postgres@hqdc034:~$
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```
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#### 建立第六次快照
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10M rows in test table
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```
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2019-09-06 09:22:30 [changch@hqdc034 ~]$ sudo zfs snapshot zp/database@demo_db_test_table_with_10M_rows
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2019-09-06 09:25:18 [changch@hqdc034 ~]$ sudo zfs list -t snapshot
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NAME USED AVAIL REFER MOUNTPOINT
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zp/database@init_db_no_demo 250K - 231M -
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zp/database@demo_db_just_restore 138K - 2.08G -
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zp/database@demo_db_create_test_table_but_no_data 116K - 2.08G -
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zp/database@demo_db_test_table_with_1M_rows 218K - 2.15G -
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zp/database@demo_db_test_table_with_2M_rows 530K - 2.23G -
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zp/database@demo_db_test_table_with_10M_rows 163K - 2.97G -
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2019-09-06 09:25:21 [changch@hqdc034 ~]$
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```
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到1000萬筆資料為止，現在資料庫大小是這樣
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```
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postgres@hqdc034:~$ du -sh /zp/database/10/main/
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3.0G /zp/database/10/main/
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postgres@hqdc034:~$
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```
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***
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### 還原測試
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最後一次做快照的時候，demo DB 裡面有一千萬筆資料，現在來砍掉500萬筆
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```
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postgres@hqdc034:~$ time psql -c 'delete from test where a > 5000000;'
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DELETE 3000000
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real 0m7.844s
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user 0m0.024s
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sys 0m0.004s
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postgres@hqdc034:~$ time psql -c 'select count(*) from test;'
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count
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---------
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7000000
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(1 row)
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real 0m0.268s
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user 0m0.024s
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sys 0m0.004s
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postgres@hqdc034:~$
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```
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咦，怪怪的，為什麼只有砍掉300萬筆？
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好，這邊先不管，等等正好來驗證restore的狀況
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假設剛剛這個刪除是錯誤的動作，我要回到1000萬資料的狀態，就可以用zfs rollback 來達成
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#### 第一次還原
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目標是還原到包含1000萬筆資料的狀態(現在是700萬筆)
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```
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2019-09-06 09:25:21 [changch@hqdc034 ~]$ sudo service postgresql stop
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* Stopping PostgreSQL 10 database server [ OK ]
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2019-09-06 10:14:12 [changch@hqdc034 ~]$ sudo zfs rollback -r zp/database@demo_db_test_table_with_10M_rows
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2019-09-06 10:14:28 [changch@hqdc034 ~]$ sudo service postgresql start
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* Starting PostgreSQL 10 database server [ OK ]
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2019-09-06 10:14:57 [changch@hqdc034 ~]$
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```
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檢查一下
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```
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postgres@hqdc034:~$ time psql -c 'select count(*) from test;'
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count
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----------
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10000000
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(1 row)
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real 0m5.019s
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user 0m0.040s
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sys 0m0.008s
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postgres@hqdc034:~$
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```
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沒錯，又回到1000萬筆資料的狀態了
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要注意的是，如果回到更之前的狀態，在該狀態之後的快照將會被清除，除非你先做clone
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比如我現在要回到 200萬筆的狀態，那1000萬筆資料的快照就會被刪除
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```
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2019-09-06 10:17:32 [changch@hqdc034 ~]$ sudo service postgresql stop
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* Stopping PostgreSQL 10 database server [ OK ]
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2019-09-06 10:18:50 [changch@hqdc034 ~]$ sudo zfs rollback -r zp/database@demo_db_test_table_with_2M_rows
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2019-09-06 10:18:57 [changch@hqdc034 ~]$ sudo zfs list -t snapshot
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NAME USED AVAIL REFER MOUNTPOINT
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zp/database@init_db_no_demo 250K - 231M -
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zp/database@demo_db_just_restore 138K - 2.08G -
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zp/database@demo_db_create_test_table_but_no_data 116K - 2.08G -
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zp/database@demo_db_test_table_with_1M_rows 218K - 2.15G -
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zp/database@demo_db_test_table_with_2M_rows 0 - 2.23G -
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2019-09-06 10:19:04 [changch@hqdc034 ~]$ sudo service postgresql start
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* Starting PostgreSQL 10 database server [ OK ]
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2019-09-06 10:19:17 [changch@hqdc034 ~]$
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postgres@hqdc034:~$ time psql -c 'select count(*) from test;'
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count
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---------
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2000000
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(1 row)
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real 0m0.175s
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user 0m0.024s
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sys 0m0.008s
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postgres@hqdc034:~$
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```
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啊，我剛剛應該先clone的....
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沒關係，我們再做一次，新增800萬筆資料，湊齊1000萬筆，然後快照
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```
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postgres@hqdc034:~$ time psql -c 'with aa as ( select * from generate_series (1,8000000) a ) insert into test select aa.a, md5(aa.a::varchar) from aa;'
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INSERT 0 8000000
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real 0m35.662s
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user 0m0.048s
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sys 0m0.004s
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postgres@hqdc034:~$ time psql -c 'select count(*) from test;'
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count
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----------
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10000000
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(1 row)
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real 0m5.259s
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user 0m0.024s
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sys 0m0.008s
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postgres@hqdc034:~$
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```
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做快照
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```
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2019-09-06 10:19:17 [changch@hqdc034 ~]$ sudo zfs snapshot zp/database@demo_db_test_table_with_10M_rows
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2019-09-06 10:22:59 [changch@hqdc034 ~]$ sudo zfs list -t snapshot
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NAME USED AVAIL REFER MOUNTPOINT
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zp/database@init_db_no_demo 250K - 231M -
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zp/database@demo_db_just_restore 138K - 2.08G -
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zp/database@demo_db_create_test_table_but_no_data 116K - 2.08G -
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zp/database@demo_db_test_table_with_1M_rows 218K - 2.15G -
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zp/database@demo_db_test_table_with_2M_rows 56.4M - 2.23G -
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zp/database@demo_db_test_table_with_10M_rows 0 - 1.81G -
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2019-09-06 10:23:02 [changch@hqdc034 ~]$
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```
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接著來測試看看 clone snapshot，這是基本的說明
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```
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Clones can only be created from a snapshot and a snapshot can not
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be deleted until you delete the clone that is based on this snapshot.
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To create a clone, use the zfs clone command.
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```
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clone 會做出一份跟clone來源一模一樣的資料，在快照模式下，資料是唯讀的，clone出來後，就可以做異動。但是不能刪除clone來源的快照，會提示錯誤。
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```
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2019-09-06 10:28:31 [changch@hqdc034 ~]$ sudo zfs clone zp/database@demo_db_test_table_with_10M_rows zp/database/clone_with_10M_rows
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2019-09-06 10:29:21 [changch@hqdc034 ~]$ sudo zfs list
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NAME USED AVAIL REFER MOUNTPOINT
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zp 3.08G 231G 22K /zp
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zp/database 3.08G 231G 1.88G /zp/database
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zp/database/clone_with_10M_rows 0 231G 1.81G /zp/database/clone_with_10M_rows
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2019-09-06 10:29:26 [changch@hqdc034 ~]$
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```
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可以看到做了clone之後，多了一個 zfs dataset
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試試看把資料庫路徑直接改到這個新做的dataset 看看能不能啟動資料庫
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修改 /etc/postgresql/10/main/postgresql.conf，然後重起postgresql
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```
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#data_directory = '/var/lib/postgresql/10/main' # use data in another directory
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#data_directory = '/zp/database/10/main'
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data_directory = '/zp/database/clone_with_10M_rows/10/main'
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```
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**啟動有比較久一點** 而且好像沒成功啟動
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```
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2019-09-06 10:32:27 [changch@hqdc034 ~]$ sudo service postgresql restart
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* Restarting PostgreSQL 10 database server [ OK ]
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2019-09-06 10:33:37 [changch@hqdc034 ~]$
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2019-09-06 10:33:37 [changch@hqdc034 ~]$ sudo netstat -antlp |grep 5432
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```
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而且在 syslog & postgresql log 中看不到什麼異常，怪了！
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而且再啟動一次就好了？
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再來測試一次看看
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```
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2019-09-06 10:37:22 [changch@hqdc034 ~]$ sudo service postgresql stop
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||||
* Stopping PostgreSQL 10 database server [ OK ]
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||||
2019-09-06 10:38:03 [changch@hqdc034 ~]$ sudo zfs list
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NAME USED AVAIL REFER MOUNTPOINT
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zp 3.24G 231G 22K /zp
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zp/database 3.24G 231G 1.88G /zp/database
|
||||
zp/database/clone_with_10M_rows 165M 231G 1.88G /zp/database/clone_with_10M_rows
|
||||
2019-09-06 10:38:13 [changch@hqdc034 ~]$ sudo zfs destroy zp/database/clone_with_10M_rows
|
||||
2019-09-06 10:38:21 [changch@hqdc034 ~]$ sudo zfs clone zp/database@demo_db_test_table_with_10M_rows zp/database/clone_with_10M_rows
|
||||
2019-09-06 10:38:32 [changch@hqdc034 ~]$ sudo zfs list
|
||||
NAME USED AVAIL REFER MOUNTPOINT
|
||||
zp 3.08G 231G 22K /zp
|
||||
zp/database 3.08G 231G 1.88G /zp/database
|
||||
zp/database/clone_with_10M_rows 0 231G 1.81G /zp/database/clone_with_10M_rows
|
||||
2019-09-06 10:38:35 [changch@hqdc034 ~]$ sudo service postgresql start^C
|
||||
2019-09-06 10:38:44 [changch@hqdc034 ~]$ sudo zfs list
|
||||
NAME USED AVAIL REFER MOUNTPOINT
|
||||
zp 3.08G 231G 22K /zp
|
||||
zp/database 3.08G 231G 1.88G /zp/database
|
||||
zp/database/clone_with_10M_rows 0 231G 1.81G /zp/database/clone_with_10M_rows
|
||||
2019-09-06 10:38:45 [changch@hqdc034 ~]$ sudo service postgresql start
|
||||
* Starting PostgreSQL 10 database server [ OK ]
|
||||
2019-09-06 10:39:04 [changch@hqdc034 ~]$ netstat -antlp |grep 5432
|
||||
(Not all processes could be identified, non-owned process info
|
||||
will not be shown, you would have to be root to see it all.)
|
||||
tcp 0 0 0.0.0.0:5432 0.0.0.0:* LISTEN -
|
||||
tcp6 0 0 :::5432 :::* LISTEN -
|
||||
2019-09-06 10:39:13 [changch@hqdc034 ~]$
|
||||
```
|
||||
這次就沒問題？看來是我第一次下指令的時候，不該用sudo netstat -antlp 去檢查？
|
||||
anyway ，回到psql 來看看內容
|
||||
```
|
||||
postgres@hqdc034:~$ time psql -c 'select count(*) from test;'
|
||||
count
|
||||
----------
|
||||
10000000
|
||||
(1 row)
|
||||
|
||||
|
||||
real 0m4.716s
|
||||
user 0m0.028s
|
||||
sys 0m0.004s
|
||||
postgres@hqdc034:~$
|
||||
```
|
||||
|
||||
Good ，clone 出來的果然是1000萬筆資料時的狀態
|
||||
|
||||
***
|
||||
|
||||
這次測試就先到此為止，後面再來測試zfs的 replication and send/recv
|
||||
Reference in New Issue
Block a user