Sorry, it was a typo , I meant to say 1GB only.
I would say break the problem like the following.
1. Run some fio workload say (1G) on RBD and run ceph command like ‘ceph df’ to see how much data it written. I am sure you will be seeing same data. Remember
by default ceph rados object size is 4MB, so, it should write 1GB/4MB number of objects.
2. Also, you can use ‘rados’ utility to directly put/get say 1GB file to the cluster and check similar way.
As I said, if your journal in the same device and if you measure the space consumed by entire OSD mount point , it will be more because of WA induced by Ceph.
But, individual file size you transferred should not differ.
<< Also please let us know the reason ( Extra 2-3 mins is taken for hg
/ git repository operation like clone , pull , checkout and update.)
Could you please explain a bit what you are trying to do here ?
Thanks & Regards
Somnath
From: gjprabu [mailto:gjprabu@xxxxxxxxxxxx]
Sent: Friday, June 12, 2015 12:34 AM
To: Somnath Roy
Cc: ceph-users@xxxxxxxxxxxxxx; Kamala Subramani ; Siva Sokkumuthu
Subject: Re: RE: RE: [ceph-users] Ceph OSD with OCFS2
Hi,
I measured the data only what i transfered from client. Example 500MB file transfered after complete if i measured the same file size will be 1GB not 10GB.
Our Configuration is :-
=============================================================================================
ceph -w
cluster f428f5d6-7323-4254-9f66-56a21b099c1a
health HEALTH_OK
monmap e1: 3 mons at {cephadmin=172.20.19.235:6789/0,cephnode1=172.20.7.168:6789/0,cephnode2=172.20.9.41:6789/0}, election epoch 114, quorum 0,1,2 cephnode1,cephnode2,cephadmin
osdmap e9: 2 osds: 2 up, 2 in
pgmap v1022: 64 pgs, 1 pools, 7507 MB data, 1952 objects
26139 MB used, 277 GB / 302 GB avail
64 active+clean
===============================================================================================
ceph.conf
[global]
osd pool default size = 2
auth_service_required = cephx
filestore_xattr_use_omap = true
auth_client_required = cephx
auth_cluster_required = cephx
mon_host = 172.20.7.168,172.20.9.41,172.20.19.235
mon_initial_members = zoho-cephnode1, zoho-cephnode2, zoho-cephadmin
fsid = f428f5d6-7323-4254-9f66-56a21b099c1a
================================================================================================
What is the replication policy you are using ?
We are using default OSD with 2 replica not using CRUSH Map, PG num and
Erasure etc.,
What interface you used to store the data ?
We are using RBD to store data and its has been mounted with OCFS2 in client side.
How are you removing data ? Are you removing a rbd image ?
We are not removing rbd image, only removing data which is already having and removing using rm command from client. We didn't set async way to transfer or remove data
Also please let us know the reason ( Extra 2-3 mins is taken for hg / git repository operation like clone , pull , checkout and update.)
Hi,
Ceph journal works in different way. It’s a write ahead journal, all the data will be persisted first in journal and then will be written to actual place. Journal data is encoded.
Journal is a fixed size partition/file and written sequentially. So, if you are placing journal in HDDs, it will be overwritten, for SSD case , it will be GC later. So, if you are measuring amount of data written to the device it will be double. But, if you
are saying you have written a 500MB file to cluster and you are seeing the actual file size is 10G, it should not be the case. How are you seeing this size BTW ?
Could you please tell us more about your configuration ?
What is the replication policy you are using ?
What interface you used to store the data ?
Regarding your other query..
<< If i transfer 1GB data, what will be server size(OSD), Is this will write compressed format
No, actual data is not compressed. You don’t want to fill up OSD disk and there are some limits you can set . Check the following link
http://ceph.com/docs/master/rados/troubleshooting/troubleshooting-osd/
It will stop working if the disk is 95% full by default.
<< Is it possible to take backup from server compressed data and copy the same to other machine as Server_Backup - then start new client using Server_Backup
For backup, check the following link if that works for you.
https://ceph.com/community/blog/tag/backup/
Also, you can use RGW federated config for back up.
<< Data removal is very slow
How are you removing data ? Are you removing a rbd image ?
If you are removing entire pool , that should be fast and do deletes data async way I guess.
Thanks & Regards
Somnath
Hi Team,
Once data transfer completed the journal file should convert all memory data's to real places but our cause it showing double of the size after complete transfer, Here everyone will confuse what is real file and folder size. Also What will happen If i move
the monitoring from that osd server to separately, is the double size issue may solve ?
We have below query also.
1. Extra 2-3 mins is taken for hg / git repository operation like clone , pull , checkout and update.
2. If i transfer 1GB data, what will be server size(OSD), Is this will write compressed format.
3 . Is it possible to take backup from server compressed data and copy the same to other machine as Server_Backup - then start new client using Server_Backup.
4. Data removal is very slow.
Yes, Ceph will be writing twice , one for journal and one for actual data. Considering you configured journal in the same device , this is what you end up seeing if you are monitoring
the device BW.
Thanks & Regards
Somnath
Dear Team,
We are newly using ceph with two OSD and two clients. Both clients are mounted with OCFS2 file system. Here suppose i transfer 500MB of data in the client its showing double of the size 1GB after finish data transfer. Is the behavior is correct or is there
any solution for this.
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