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19 Posts
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6161
July 14th, 2010 05:00
Centera Storage Nodes Capacity
Dear Folks,
I'd like to know the maximum capacity of a node in storage role if the avg. file size is 2,4MB for CPM and CPP mode. I hope you can help me,
kind regards,
Markus Holzhauer
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Gq15Ssx2wt12372
16 Posts
1
July 14th, 2010 09:00
Parity (CPP) is a more space efficient way to store data. Whereas mirroring requires a 100% overhead of disk space for each stored object, the additional disk space for CPP is only 1/6 of the object size. Access nodes split data that need to be stored into 6 segments and exports these segments to different storage nodes in the same cluster.
Gq15Ssx2wt12372
16 Posts
1
July 14th, 2010 09:00
Whenever data is written to a cluster some KB will be utilised for metadata information besides the actual file size
CPM - 2.4MB per node (2.4 MB will also be duplicated to a second storage node)
CPP - .4MB per node (2.4MB divided by 6, as data is stored in fragments in CPP mode)
mholzhauer
19 Posts
0
July 15th, 2010 02:00
Dear Mamatha,
thanks for your answers, but unfortunately you didnt answer my original question with that. I want to know the precise value of the maximum capacity (in TB, GB or whatever) per node, if the archived data is expected to be 2,4MB of average size. Since CPP and CPM differ regarding their capacity requirements I would like to know this precise value for each protection mode.
So an excellent answer would be:
Thank you,
Markus
mholzhauer
19 Posts
0
July 15th, 2010 05:00
Hi people,
thats a very helpful table indeed. But how can i calculate the available capacities for a node using CPM or CPP. I have a feeling that this depends on the avg. file size (2,4MB) of the archived files. Which factor(s) do I have to use on the "available capacity" in your table?
Thanks,
Markus
mholzhauer
19 Posts
0
July 16th, 2010 00:00
Hi Dan,
that's exactly what I was looking for, thank you. But still I think that it's not so easy. If what you say was true, then I if I had a cluster of 8 nodes gen4lp (2TB) with about 7.2TB per node, so 8*7.2TB = 57.6TB in total, I just had to multiply it with 0.5 (CPM) or 0.75 (CPP) to receive the amount of data that could be stored on the cluster. But if you look at the current technical data sheet of the centera (http://germany.emc.com/collateral/hardware/specification-sheet/c932-centera-cas-ss.pdf) you see, that this is not the case.
That's the reason why I am looking for an up to date table likes this one:
which I found in the centera online help pdf powerlink (which unfortunately wasn't updated since 2005). Additionally to that I think, that it is not possible to use all of the nodes in a cluster for storing data since I do need some nodes in the access role too. Or is it already common to use the feature which allows you to use both roles on one node (and does the customer still have to buy a seperate licence for this?)?
I really do appreciate your gelp guys,
Markus