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Create iSCSI disc in EC Pool


devslashzero
12 Posts
May 15, 2023, 11:18 am

Hello,

I have a fresh cluster with the following node definition:

  • Amount of nodes: 6
  • SSDs per Node: 24
  • Size of each SSD: 750 GB

I created an EC Pool with k=4 and m=2 and 4096 PGs so I can continue running with max 2 nodes down in case of emergency.

When I try to create an iSCSI disc, the system is asking me for a replicated pool with the created [4,2]-pool as data pool. So here is my question:

How can I define the replicated pool? I mean, I just want an iSCSI disc running on the EC Pool.

Thanks in advance for advice.

#1

admin
2,930 Posts
May 15, 2023, 12:24 pm

You need a replicated pool to store metadata of the disks, data will be stored in ec pool but ec pool cannot store metadata (omap )

So just create an extra replicated pool to use/share the same SSDs as the ec pool. You can assign low PG count to this pool since it will not store much.

Then when you create a new disk, you will assign both replicated (for metadata) and ec (for data) pools.

 

#2

devslashzero
12 Posts
May 15, 2023, 12:40 pm

Really many thanks you for the answer.

So what would be your suggetion for Number of PGs, Size, Min Size for the replicated pool? Should I take the rule By-Host-SSD for it?

#3

admin
2,930 Posts
May 15, 2023, 11:21 pm

size 4 min size 2   num of PG=16

yes by-host-ssd for replicated pool, ec-by-host-ssd for ec

Last edited on May 15, 2023, 11:21 pm by admin · #4