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Raid 5 Question ?

Danel_1
Frequent Advisor

Raid 5 Question ?

Hi ,

Is anyone know how work the netraid5 volumes.

in 4 nodes Cluster , the provisionning size for one volume (full provis.)is the same for a Netraid10 or netraid5 (single parity)volume ?

I don't find documantation about this.

Thanks

Didier DANEL
9 REPLIES
Bart_Heungens
Honored Contributor

Re: Raid 5 Question ?

I do not know exactly what you mean but I suppose it is the following:

With network RAID 10 (before it was called replication level 2) with 4 nodes you will loose 2 nodes because of the RAID 10 replication.

With network RAID 5, 3 nodes will be used to write blocks of data, the 4th node will be used for the parity block.

So with RAID 5 you have more effective space available as with RAID 10. With RAID 5 you loose the disk space of 1 node, with RAID 10 it is 50%.

FYI RAID 5 is possible from 4 nodes on, RAID 6 is available starting from 6 nodes...
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Johan Guldmyr
Honored Contributor

Re: Raid 5 Question ?

Is the parity spread out between the nodes?
Danel_1
Frequent Advisor

Re: Raid 5 Question ?

In fact the netraid 5 volumes(full provisionning) with 4 nodes consume exactly the same space that the netraid 10 volume

I don't understand , because if 3 nodes are used for data blocks and one node for Parity block , only 25% of space shoulf be lost.

thanks

Didier D.
Bart_Heungens
Honored Contributor

Re: Raid 5 Question ?

This is indeed the normal space usage being 25% lost with 4 nodes.

Can you provide some screenshots?

I assume you created a single site cluster and not a multi site?
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Jitun
HPE Pro

Re: Raid 5 Question ?

Under SANiQ 9.0 you only require 3 nodes for implementing network RAID 5 and 5 nodes for n/w RAID 6

I would recommend n/w RAID 5 only is your rate of change of the volume is 0-10%/day
Mostly Archival volumes, Large File shares, Remote Copy in DR Sites.
Volumes are mostly Read.

It delivers approximately 60% utilization of raw disk capacity assuming disk RAID 5 in storage nodes plus Network RAID 5 across nodes.
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Danel_1
Frequent Advisor

Re: Raid 5 Question ?

ok ,
I will take screenshots asap.
Yes the cluster is standard .
do you have some documents or white papers about block distribution for Raid5 ...

thank you


Bart_Heungens
Honored Contributor

Re: Raid 5 Question ?

I have some screenshots from the HP training material which I am not allowed to shate unfortenatelly...
But it is simpel:
RAID 5 is 3 data blocks and & parity block (parity blocks spread accross the 4 nodes)
RAID 6 is 4 data blocks and 2 parity blocks
(parity blocks spread accross the 6 nodes)

I'll see if I can find public documents with the drawings...
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Danel_1
Frequent Advisor

Re: Raid 5 Question ?

Hi Bart ,

can you to send me the internal pointer
didier.danel@hp.com

Thank you
Jitun
HPE Pro

Re: Raid 5 Question ?

Sent u the email.
Hope it helps.
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