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mmchalla1
1 Copper

How to find the rate of changed data on a volume

Hi,

I'm working on a  replication solutions for DR.  I need to know the delta changes on a volume to estimate the bandwidth requirements.  As on now, the chekpoints are set at every half-an-hour on the volume.

How to get the delta between two checkpoints?

BR

Murali

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7 Replies
gbarretoxx1
3 Argentium

Re: How to find the rate of changed data on a volume

Hi,

Please, see the following solution :

https://community.emc.com/docs/DOC-7340

If you simply do a server_df, you will see the difference between the checkpoints :

[root@CS_NS40_1_MSS nasadmin]# server_df server_2 |grep fs01_
fs01_ckpt5      64019696     21496632     42523064   34%    /fs01_ckpt5
fs01_ckpt4      64019696     39398480     24621216   62%    /fs01_ckpt4
fs01_ckpt3      64019696     37806448     26213248   59%    /fs01_ckpt3
fs01_ckpt2      64019696     38800664     25219032   61%    /fs01_ckpt2
fs01_ckpt1      64019696     43595360     20424336   68%    /fs01_ckpt1


The above output shows the capacity of the production file system (PFS) when each checkpoint was taken or refreshed.

Gustavo Barreto.

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Rainer_EMC
5 Osmium

Re: How to find the rate of changed data on a volume

note that this is the capacity at the time the ckpt was taken and not exactly the change rate

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gbarretoxx1
3 Argentium

Re: How to find the rate of changed data on a volume

Hi Rainer,

Yes, you are correct.

These values can be used as "estimated change rate" between the checkpoints.

Gustavo Barreto.

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mmchalla1
1 Copper

Re: How to find the rate of changed data on a volume

Hi,

thank you for the solution.  However, I have seen no changes between the checkpoints generated.  Here is the output (I have put that in excel to format and also added date and time for reference)

Check Point NameAllotted SizeUsed SizeFree Size%Mounted onDateTime
ckpt_data1_ckpt_Schedule_30mins_Past_Hour_02830977278412665172818312105641%/root_vdm_2/ckpt_data1_ckpt_Schedule_30mins_Past_Hour_02804-Jul3:30
ckpt_data1_ckpt_Schedule_30mins_Past_Hour_03730977278412670196818307081641%/root_vdm_2/ckpt_data1_ckpt_Schedule_30mins_Past_Hour_03705-Jul0:30
ckpt_data1_ckpt_Schedule_30mins_Past_Hour_00430977278412670409618306868841%/root_vdm_2/ckpt_data1_ckpt_Schedule_30mins_Past_Hour_00405-Jul3:30
ckpt_data1_ckpt_Schedule_30mins_Past_Hour_01330977278412671020818306257641%/root_vdm_2/ckpt_data1_ckpt_Schedule_30mins_Past_Hour_01306-Jul0:30
ckpt_data2_ckpt_Schedule_30mins_Past_Hour_02830977278414444161616533116847%/root_vdm_2/ckpt_data2_ckpt_Schedule_30mins_Past_Hour_02804-Jul3:30
ckpt_data2_ckpt_Schedule_30mins_Past_Hour_03730977278414442098416535180047%/root_vdm_2/ckpt_data2_ckpt_Schedule_30mins_Past_Hour_03705-Jul0:30
ckpt_data2_ckpt_Schedule_30mins_Past_Hour_00430977278414442584816534693647%/root_vdm_2/ckpt_data2_ckpt_Schedule_30mins_Past_Hour_00405-Jul3:30
ckpt_data2_ckpt_Schedule_30mins_Past_Hour_01330977278414927523216049755248%/root_vdm_2/ckpt_data2_ckpt_Schedule_30mins_Past_Hour_01306-Jul0:30
ckpt_data3_ckpt_Schedule_30mins_Past_Hour_02830977278415578399215398879250%/root_vdm_2/ckpt_data3_ckpt_Schedule_30mins_Past_Hour_02804-Jul3:30
ckpt_data3_ckpt_Schedule_30mins_Past_Hour_03730977278415585315215391963250%/root_vdm_2/ckpt_data3_ckpt_Schedule_30mins_Past_Hour_03705-Jul0:30
ckpt_data3_ckpt_Schedule_30mins_Past_Hour_00430977278415593099215384179250%/root_vdm_2/ckpt_data3_ckpt_Schedule_30mins_Past_Hour_00405-Jul3:30
ckpt_data3_ckpt_Schedule_30mins_Past_Hour_01330977278415593569615383708850%/root_vdm_2/ckpt_data3_ckpt_Schedule_30mins_Past_Hour_01306-Jul0:30
ckpt_data4_ckpt_Schedule_30mins_Past_Hour_02830977278418297234412680044059%/root_vdm_2/ckpt_data4_ckpt_Schedule_30mins_Past_Hour_02804-Jul3:30
ckpt_data4_ckpt_Schedule_30mins_Past_Hour_03730977278418297545612679732859%/root_vdm_2/ckpt_data4_ckpt_Schedule_30mins_Past_Hour_03705-Jul0:30
ckpt_data4_ckpt_Schedule_30mins_Past_Hour_00430977278418260255212717023259%/root_vdm_2/ckpt_data4_ckpt_Schedule_30mins_Past_Hour_00405-Jul3:30
ckpt_data4_ckpt_Schedule_30mins_Past_Hour_01330977278418264659212712619259%/root_vdm_2/ckpt_data4_ckpt_Schedule_30mins_Past_Hour_01306-Jul0:30
ckpt_data5_ckpt_Schedule_30mins_Past_Hour_01330977278416264362414712916053%/root_vdm_2/ckpt_data5_ckpt_Schedule_30mins_Past_Hour_01304-Jul0:30
ckpt_data5_ckpt_Schedule_30mins_Past_Hour_02430977278416267504814709773653%/root_vdm_2/ckpt_data5_ckpt_Schedule_30mins_Past_Hour_02404-Jul3:30
ckpt_data5_ckpt_Schedule_30mins_Past_Hour_03330977278416601395214375883254%/root_vdm_2/ckpt_data5_ckpt_Schedule_30mins_Past_Hour_03305-Jul0:30
ckpt_data5_ckpt_Schedule_30mins_Past_Hour_04430977278416603790414373488054%/root_vdm_2/ckpt_data5_ckpt_Schedule_30mins_Past_Hour_04405-Jul3:30
ckpt_data5_ckpt_Schedule_30mins_Past_Hour_00530977278416614626414362652054%/root_vdm_2/ckpt_data5_ckpt_Schedule_30mins_Past_Hour_00506-Jul0:30
ckpt_data6_ckpt_Schedule_30mins_Past_Hour_01330977278420455637610521640866%/root_vdm_2/ckpt_data6_ckpt_Schedule_30mins_Past_Hour_01304-Jul0:30
ckpt_data6_ckpt_Schedule_30mins_Past_Hour_02430977278420460529610516748866%/root_vdm_2/ckpt_data6_ckpt_Schedule_30mins_Past_Hour_02404-Jul3:30
ckpt_data6_ckpt_Schedule_30mins_Past_Hour_03330977278420461560810515717666%/root_vdm_2/ckpt_data6_ckpt_Schedule_30mins_Past_Hour_03305-Jul0:30
ckpt_data6_ckpt_Schedule_30mins_Past_Hour_04430977278420501328010475950466%/root_vdm_2/ckpt_data6_ckpt_Schedule_30mins_Past_Hour_04405-Jul3:30
ckpt_data6_ckpt_Schedule_30mins_Past_Hour_00530977278420508926410468352066%/root_vdm_2/ckpt_data6_ckpt_Schedule_30mins_Past_Hour_00506-Jul0:30

I have 6 volumes in total accessed by about 500 users 24 x 7, each volume of size 300 GB.  Data may be updated as per their requirements.  As per the above table - there are no changes at all between the checkpoints?

BR

Murali

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gbarretoxx1
3 Argentium

Re: How to find the rate of changed data on a volume

Hi,

Let's take these two ones as examples :

ckpt_data6_ckpt_Schedule_30mins_Past_Hour_03330977278420461560810515717666%/root_vdm_2/ckpt_data6_ckpt_Schedule_30mins_Past_Hour_03305-Jul0:30
ckpt_data6_ckpt_Schedule_30mins_Past_Hour_04430977278420501328010475950466%/root_vdm_2/ckpt_data6_ckpt_Schedule_30mins_Past_Hour_04405-Jul3:30

When ckpt_data6_ckpt_Schedule_30mins_Past_Hour_033 was created or refreshed, the PFS had 204615608 used.

When ckpt_data6_ckpt_Schedule_30mins_Past_Hour_044 was created or refreshed, the PFS had 205013280 used.

There are changes between the checkpoints.

You can see when they were created or refreshed with :

# nas_fs -i ckpt_data6_ckpt_Schedule_30mins_Past_Hour_033 |grep checkpt_of

# nas_fs -i ckpt_data6_ckpt_Schedule_30mins_Past_Hour_044 |grep checkpt_of

As previously said, this is not the precise change rate, but you can use the difference as a reference.

Gustavo Barreto.

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DanJost
3 Argentium

Re: How to find the rate of changed data on a volume

A much less-granular but another way to look at the volumes is to check your "level 1" backups - it won't pick up temporary "things" but it will show you what is being added and modified for the day.  Depending upon the workload (i.e. it is a file server for end users that don't create tons of temporary/transient files) this might be a good indicator for the total adds/modifies for a day.  The checkpoints pick up deletes and while they are "replicated" I don't think they would make you consume a lot of bandwidth.  Of course, looking at it this way doesn't show you the highs and lows you may experience throughout the day...

Dan

mmchalla1
1 Copper

Re: How to find the rate of changed data on a volume

Hi,

I have started calculating the difference between the checkpoints and found to be a good base to understand the rate of data change. I thank you all for the help.

Murali

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