OpenStack Object Storage (swift)

Data location in storage nodes

Asked by Jorge Henrique

Hi,

   We have set up a swift cloud and it is working well. However, we don't know which zones swift is using to store a specific data. Is there any way to do that ? Also, is there any way to have statistics to see which zone are the most used ?

                Thanks,

            Jorge

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Florian Hines
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Best Florian Hines (pandemicsyn) said : 		#1

You can see the location of a specific account, container, or object using swift-get-nodes:

fhines@ubuntu:~$ swift-get-nodes
Usage: /usr/local/bin/swift-get-nodes [-a] <ring.gz> <account> [<container>] [<object>]
Shows the nodes responsible for the item specified.
Example:
    $ /usr/local/bin/swift-get-nodes /etc/swift/account.ring.gz MyAccount
    Partition 5743883
    Hash 96ae332a60b58910784e4417a03e1ad0
    10.1.1.7:8000 sdd1
    10.1.9.2:8000 sdb1
    10.1.5.5:8000 sdf1
    10.1.5.9:8000 sdt1 # [Handoff]

I'm not sure what types of stats you want but checking disk usage is an easy way to see if your balanced from disk usage perspective.

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Jorge Henrique (jorhen111) said : 		#2

Thanks Florian Hines, that solved my question.

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sujay (sujay-m17) said : 		#4

Hi Florian Hines, thanks for the info. I have a small doubt.

I have set up Swift all in one with loopback as storage

How does swift locate the objects with the help of the containers table in the account folder.

sqlite> select * from account_stat;
AUTH_test|1351964500.78340|1351964500.71905|0|2|1|3086|1f701b5602c1aa6f08598ca35515b757|225c855a-20d8-4754-a3f0-c7244f32e9d3||0|
sqlite> select * from container;
3|myContainer1|1351966542.56171|0|1|3086|0
4|publicContainer|1352176822.54750|0|0|0|0

How does swift use the above info to locate the objects of the container

sujay@ubuntu:/srv/2/node/sdb2/accounts/56335/281/3703f658243cec0da307d210a2678281$ swift-get-nodes /etc/swift/account.ring.gz test myContainer1 README.md

Account test
Container myContainer1
Object README.md

Partition 128322
Hash 7d509816c039ae6c6accb56198288b23

Server:Port Device 127.0.0.1:6022 sdb2
Server:Port Device 127.0.0.1:6032 sdb3
Server:Port Device 127.0.0.1:6042 sdb4
Server:Port Device 127.0.0.1:6012 sdb1 [Handoff]

curl -I -XHEAD "http://127.0.0.1:6022/sdb2/128322/test/myContainer1/README.md"
curl -I -XHEAD "http://127.0.0.1:6032/sdb3/128322/test/myContainer1/README.md"
curl -I -XHEAD "http://127.0.0.1:6042/sdb4/128322/test/myContainer1/README.md"
curl -I -XHEAD "http://127.0.0.1:6012/sdb1/128322/test/myContainer1/README.md" # [Handoff]

ssh 127.0.0.1 "ls -lah /srv/node/sdb2/objects/128322/b23/7d509816c039ae6c6accb56198288b23/"
ssh 127.0.0.1 "ls -lah /srv/node/sdb3/objects/128322/b23/7d509816c039ae6c6accb56198288b23/"
ssh 127.0.0.1 "ls -lah /srv/node/sdb4/objects/128322/b23/7d509816c039ae6c6accb56198288b23/"
ssh 127.0.0.1 "ls -lah /srv/node/sdb1/objects/128322/b23/7d509816c039ae6c6accb56198288b23/" # [Handoff]

or how will this help in locating the object?

what does HandOff mean?