easy way to calculate how much disk space is needed?

[markm75]

I came across a DPM calculator (spreadsheet) at one point, but found it too
complex for a quick easy calculation on the kind of space we would need..

At this point we have about 1520GB of data... our DPM server has 2.8TB of
total space and we are maxed out and replicas and nightly backups are failing
due to lack of space...

We also have room to add about 1.9TB more data on all of our backed up
servers combined..

So, since it appears that 3.5TB would be the absolute min for our current
data usage (7 day retention only, not 30 as we'd hoped)... is there some easy
way to calculate this need, besides that spreadsheet?

IE: adding 1.9TB would take us to the 3.5TB of data easily.. does this
imply for 7 day backups that we'd need roughly 7TB of space available? And
if we add another 3TB server, to completely cover that space.. this means
10TB to include all future space usage? (we actually will be adding another
server with a max of 3TB available and would want that space covered, not
just the existing data)..

I realize its difficult to predict, especially with sql db's.. but there
must be some general rule.

Any thoughts.. are my guesses close?

[Mukul Shekhawat [MSFT]]

Hi Mark,

You can find and easy way to approximate the size calculation from this
article.

http://blogs.technet.com/dpm/archive/2008/03/27/dpm-v2-disk-allocation-calculations.aspx
--
Thanks and Regards
Mukul

This posting is provided "AS IS" with no warranties, and confers no rights.

Post by markm75
I came across a DPM calculator (spreadsheet) at one point, but found it too
complex for a quick easy calculation on the kind of space we would need..
At this point we have about 1520GB of data... our DPM server has 2.8TB of
total space and we are maxed out and replicas and nightly backups are failing
due to lack of space...
We also have room to add about 1.9TB more data on all of our backed up
servers combined..
So, since it appears that 3.5TB would be the absolute min for our current
data usage (7 day retention only, not 30 as we'd hoped)... is there some easy
way to calculate this need, besides that spreadsheet?
IE: adding 1.9TB would take us to the 3.5TB of data easily.. does this
imply for 7 day backups that we'd need roughly 7TB of space available?
And
if we add another 3TB server, to completely cover that space.. this means
10TB to include all future space usage? (we actually will be adding another
server with a max of 3TB available and would want that space covered, not
just the existing data)..
I realize its difficult to predict, especially with sql db's.. but there
must be some general rule.
Any thoughts.. are my guesses close?

[markm75]

Post by Mukul Shekhawat [MSFT]
Hi Mark,
You can find and easy way to approximate the size calculation from this
article.
http://blogs.technet.com/dpm/archive/2008/03/27/dpm-v2-disk-allocation-calculations.aspx
--
Thanks and Regards
Mukul

Thanks.. i tried this out.. however, i chose to just lump all the data into
the first calculation, not doing sql data seperately as this would be painful
given the amount of DB's we have.. i was hoping the figure would match where
we are at now..

So i took our current total size of data which is 1500 GB roughly.. plugged
it into the first equations like this:

SC = (1500 * 7 * 2) /100 +1 =211

Replica = (1500 * 3 ) /2 = 2250

This gave a value of 2400 GB.. however, this isnt accurate.. right now we
are at roughly 2800GB but out of space.. so a value of say 3100 would have
been more accurrate..

Or perhaps i cant simply lump sum all of our data into this calculation
without using the sql and exchange ones?

It would be nice if you could just add up total space on all data drives..
to give say a value of 5000 and then be able to say.. ok, this means roughly
we need 10TB of space on the dpm server...

[markm75]

Post by Mukul Shekhawat [MSFT]
Hi Mark,
You can find and easy way to approximate the size calculation from this
article.
http://blogs.technet.com/dpm/archive/2008/03/27/dpm-v2-disk-allocation-calculations.aspx

Curious.. do you know what the "2" value in recovery points (SC size) is, or
the replica size value of *3?

IE: we only do nightly recovery points, not multiple times a day, i'm
guessing the 2 or 3 reflects 2 or 3 RP's a day?

[RuudB]

Hi Mark,
It is not clear to me whether or not you have seen the DPMVolumeSizing tool
that was created for the purpose you indicate
http://www.microsoft.com/downloads/details.aspx?FamilyID=445BC0CD-FC93-480D-98F0-3A5FB05D18D0&displaylang=en

When yes, let us discuss further about it’s shortcomings and see what we can
do about it (I created the tool).
When not, have a look and let me know what you think about it.

Thanks
Ruud

Post by markm75
I came across a DPM calculator (spreadsheet) at one point, but found it too
complex for a quick easy calculation on the kind of space we would need..
At this point we have about 1520GB of data... our DPM server has 2.8TB of
total space and we are maxed out and replicas and nightly backups are failing
due to lack of space...
We also have room to add about 1.9TB more data on all of our backed up
servers combined..
So, since it appears that 3.5TB would be the absolute min for our current
data usage (7 day retention only, not 30 as we'd hoped)... is there some easy
way to calculate this need, besides that spreadsheet?
IE: adding 1.9TB would take us to the 3.5TB of data easily.. does this
imply for 7 day backups that we'd need roughly 7TB of space available? And
if we add another 3TB server, to completely cover that space.. this means
10TB to include all future space usage? (we actually will be adding another
server with a max of 3TB available and would want that space covered, not
just the existing data)..
I realize its difficult to predict, especially with sql db's.. but there
must be some general rule.
Any thoughts.. are my guesses close?

[markm75]

Post by Mukul Shekhawat [MSFT]
Hi Mark,
It is not clear to me whether or not you have seen the DPMVolumeSizing tool
that was created for the purpose you indicate.
http://www.microsoft.com/downloads/details.aspx?FamilyID=445BC0CD-FC93-480D-98F0-3A5FB05D18D0&displaylang=en
When yes, let us discuss further about it’s shortcomings and see what we can
do about it (I created the tool).
When not, have a look and let me know what you think about it.
Thanks
Ruud

I'm taking a look at it now..

The spreadsheet is nice, though again, i wish there was a way to say.. "i
have 1500GB of data.. so this requires XXXXGB of backup space" in one lump
sum.. just plopping in the value of current data in the data area reveals a
similar 2500 or so value which isnt accurrate.. so i guess the only way is to
go through and add everything up... (but this doesnt help in the case of,
well.. we have 3TB of free space, so if this gets filled up, how can you
account for that before hand)..

[RuudB]

Post by markm75

Post by Mukul Shekhawat [MSFT]
Hi Mark,
It is not clear to me whether or not you have seen the DPMVolumeSizing tool
that was created for the purpose you indicate.
http://www.microsoft.com/downloads/details.aspx?FamilyID=445BC0CD-FC93-480D-98F0-3A5FB05D18D0&displaylang=en
When yes, let us discuss further about it’s shortcomings and see what we can
do about it (I created the tool).
When not, have a look and let me know what you think about it.
Thanks
Ruud

I'm taking a look at it now..
The spreadsheet is nice, though again, i wish there was a way to say.. "i
have 1500GB of data.. so this requires XXXXGB of backup space" in one lump
sum.. just plopping in the value of current data in the data area reveals a
similar 2500 or so value which isnt accurrate.. so i guess the only way is to
go through and add everything up... (but this doesnt help in the case of,
well.. we have 3TB of free space, so if this gets filled up, how can you
account for that before hand)..

You can, rather using the scripts and import data, just use the spreadsheet.
On the first line specify 1500GB for "Used space", specify retention (say 7
days) you'll see at bottom that you need 2250GB for Replica and 211.56 for
recovery giving 24561.56GB in total.
Or did I misunderstood you?

[markm75]

I should also add..

Right now we do have servers with sql db's that get backed up as sql dbs etc..

But.. in the near future.. all this data will be under virtual servers,
which when they are backed up, get backed up as strictly data ...

So one would think that if you just add up the total data usage and plug it
into the data part of the formulas, this would give a good approx value of
size needed, but it doesnt.

secondly and off topic, i guess the downside of just backing up those
virtual servers, is that the individual data under them cant be incremently
backed up.. ie: you cant go back to 3 days ago and grab just the sql data,
you have to restore the whole virtual server (or am i wrong here).. or will
this be possible with sp1.. or maybe by simply installing a dpm client on
those and not backing them up as a whole, but by data parts through the
client..

[RuudB]

Post by markm75
I should also add..
Right now we do have servers with sql db's that get backed up as sql dbs etc..
But.. in the near future.. all this data will be under virtual servers,
which when they are backed up, get backed up as strictly data ...
So one would think that if you just add up the total data usage and plug it
into the data part of the formulas, this would give a good approx value of
size needed, but it doesnt.
secondly and off topic, i guess the downside of just backing up those
virtual servers, is that the individual data under them cant be incremently
backed up.. ie: you cant go back to 3 days ago and grab just the sql data,
you have to restore the whole virtual server (or am i wrong here).. or will
this be possible with sp1.. or maybe by simply installing a dpm client on
those and not backing them up as a whole, but by data parts through the
client..

For VM's import or specify the total of all VHD sizes in the "DPM Virtual
server" sheet and should give you a fair ballpark figure of what you need.
Remember you are protecting the entire VM, not just SQL data unless the VM is
also running DPM agent and protected as a SQL source rather than a VM source
type.
In latter case import script output or specify SQL data in the "DPM SQL"
sheet.
Formulas the sheets use are same as published on technet.

[markm75]

I tried the SC/Replica equations further..

This time, rather than looking at the data that DPM reports is being backed
up, i looked at all data on all of our "D drives" and plugged that value into
them as below:
Actual disk use..

server1 = 1.3TB (1331)
server2 = 147
server3= 166
server4 = 416
Total= 2060

SC = (2060* 7 * 2) /100 +1 =289
Replica = (2060* 3 ) /2 = 3090
= 3300GB required for just what is used 7 day retention

This value seems to match what i think we need in space, right now, for 7
day retention (only have 2800 available).. even though the total data here is
about 400GB more than what DPM reports..

SO.. if i do the same thing, this time just taking total disk space on each
data drive.. i get this:

server1 = 2.72 TB of space (2 785.28)
server2 = 149GB
server3 = 446gb
server4 = 465GB
TOTAL = 3865 GB

SC = (3865 * 7 * 2) /100 +1 =542
Replica = (3865 * 3 ) /2 = 5797
= 6339 GB required for all free space 7 day retention


SC = (3865 * 30 * 2) /100 +1 =2320
Replica = (3865 * 3 ) /2 = 5797
= 8117 GB required for all free space 7 day retention


I think these numbers are in line? IE: if the 3300 value for our current
data size is accurate.. then if that expanded to what we could possibly have
in total.. it appears we would need roughly 6.5 TB of free space, as of right
now..

[RuudB]

Post by markm75
I tried the SC/Replica equations further..
This time, rather than looking at the data that DPM reports is being backed
up, i looked at all data on all of our "D drives" and plugged that value into
Actual disk use..
server1 = 1.3TB (1331)
server2 = 147
server3= 166
server4 = 416
Total= 2060
SC = (2060* 7 * 2) /100 +1 =289
Replica = (2060* 3 ) /2 = 3090
= 3300GB required for just what is used 7 day retention
This value seems to match what i think we need in space, right now, for 7
day retention (only have 2800 available).. even though the total data here is
about 400GB more than what DPM reports..
SO.. if i do the same thing, this time just taking total disk space on each
server1 = 2.72 TB of space (2 785.28)
server2 = 149GB
server3 = 446gb
server4 = 465GB
TOTAL = 3865 GB
SC = (3865 * 7 * 2) /100 +1 =542
Replica = (3865 * 3 ) /2 = 5797
= 6339 GB required for all free space 7 day retention
SC = (3865 * 30 * 2) /100 +1 =2320
Replica = (3865 * 3 ) /2 = 5797
= 8117 GB required for all free space 7 day retention
I think these numbers are in line? IE: if the 3300 value for our current
data size is accurate.. then if that expanded to what we could possibly have
in total.. it appears we would need roughly 6.5 TB of free space, as of right
now..

Mark I get 3380GB from calculator for protecting 2060GB with 7 days
retention (Assuming file data). According your DPM figures, it's ~5TB off on
3.4TB and is <2%, not a bad estimate although 400GB as an absolute number
sounds like a lot.