ONTAP Discussions

Flash Pool with a total of 4 SSD

alessice
736 Views

Hi,

 

we buy a new FAS2720 with 4 SSD and 8 HDD and 3 DS212C with 12 HDD each, for a total of 4 SSD 960GB and 44 HDD 4TB.

 

Now I'm configuring Flash Pool, like the old FAS2554 (4 SSD + 20 HDD) that will be migrated on the new FAS.

 

So I use the same command use some years ago on the 2554:

 

storage aggregate modify -aggregate cluster4_01_NL_SAS_1 -hybrid-enabled true

storage pool create -storage-pool StoragePool_c4_Cache1 -disk-list 1.0.0,1.0.10,1.0.1

 

now

 

storage aggregate show-spare-disks -disk-type SSD

 

show one disk as spare on node02 (the same as 2554).

 

> storage aggregate show-spare-disks -disk-type SSD
                                                                      
Original Owner: cluster4-02
 Pool0
  Spare Pool

                                                             Usable Physical
 Disk             Type   Class          RPM Checksum           Size     Size Status
 ---------------- ------ ----------- ------ -------------- -------- -------- --------
 1.0.11           SSD    solid-state      - block           894.0GB  894.3GB zeroed

 

But when I try to add flash-pool to aggregate I have this error:

 

storage aggregate add cluster4_01_NL_SAS_1 -storage-pool StoragePool_c4_Cache1 -allocation-units 4 -raidtype raid4

 

Error: command failed: storage pool "StoragePool_c4_Cache1" does not have enough spare allocation units. Use "storage pool show-available-capacity" to get the spare allocation units assigned to node cluster4-01.

 

storage pool show-available-capacity 
                           Storage SyncMirror Allocation Unit  Total
Node       Storage Pool    Type    Pool       Unit size  Count Usable Size
---------- --------------- ------- ---------- ---------- ----- -----------
cluster4-01 
           StoragePool_c4_Cache1 
                           SSD     Pool0         670.5GB     2      1.31TB
cluster4-02 
           StoragePool_c4_Cache1 
                           SSD     Pool0         670.5GB     2      1.31TB
2 entries were displayed.

 

 So, what is changed on FAS2720 and/or ONTAP 9.9.1? I remember that in the past an SSD spare can be shared from node.

 

Now I'm in difficulty if I cannot create my flash pool.

Thanks

1 ACCEPTED SOLUTION

TMACMD
715 Views

By default, two allocation units are auto-assigned to each node. That is why when you try to specify 4 units, it is failing. It would probably work with 2 units

If you >>really<< want all four units to be part of the same aggregate, you will need to reassign the other two units:

STORAGE POOL REASSIGN

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4 REPLIES 4

TMACMD
716 Views

By default, two allocation units are auto-assigned to each node. That is why when you try to specify 4 units, it is failing. It would probably work with 2 units

If you >>really<< want all four units to be part of the same aggregate, you will need to reassign the other two units:

STORAGE POOL REASSIGN

alessice
712 Views

Ok, probably understand what is wrong, on my documentation I write "-allocation-units 4" but was "2", because I need to add flash pool to 2 aggregate and if reassign a total of 4 AU to only one node is impossible to do this.

 

Here is the status of flash-pool on current FAS 2554 that I want replicated on FAS 2720:

 

cluster2::> storage pool show-disks -storage-pool ClusterCache 

Storage Pool Name: ClusterCache

             Disk
    Disk     Type    Usable Size  Total Size
    -------- ------- ----------- -----------
    1.0.0    SSD         372.4GB     372.6GB
    1.0.1    SSD         372.4GB     372.6GB
    1.0.2    SSD         372.4GB     372.6GB
3 entries were displayed.

cluster2::> storage pool show-disks -storage-pool ClusterCache -instance 

          Name of Storage Pool: ClusterCache
              Name of the disk: 1.0.0
                     Disk Type: SSD
              Disk Usable Size: 372.4GB
                    Total Size: 372.6GB
                 List of Nodes: cluster2-node01, cluster2-node02

          Name of Storage Pool: ClusterCache
              Name of the disk: 1.0.1
                     Disk Type: SSD
              Disk Usable Size: 372.4GB
                    Total Size: 372.6GB
                 List of Nodes: cluster2-node01, cluster2-node02

          Name of Storage Pool: ClusterCache
              Name of the disk: 1.0.2
                     Disk Type: SSD
              Disk Usable Size: 372.4GB
                    Total Size: 372.6GB
                 List of Nodes: cluster2-node01, cluster2-node02
3 entries were displayed.

cluster2::> storage pool show-disks -storage-pool ClusterCache           

Storage Pool Name: ClusterCache

             Disk
    Disk     Type    Usable Size  Total Size
    -------- ------- ----------- -----------
    1.0.0    SSD         372.4GB     372.6GB
    1.0.1    SSD         372.4GB     372.6GB
    1.0.2    SSD         372.4GB     372.6GB
3 entries were displayed.

cluster2::> storage aggregate show-spare-disks -disk-type SSD
                                                                      
Original Owner: cluster2-node01
 Pool0
  Spare Pool

                                                             Usable Physical
 Disk             Type   Class          RPM Checksum           Size     Size Status
 ---------------- ------ ----------- ------ -------------- -------- -------- --------
 1.0.3            SSD    solid-state      - block           372.4GB  372.6GB zeroed

cluster2::> storage pool show -storage-pool ClusterCache -instance

                        Storage Pool Name: ClusterCache
                     UUID of Storage Pool: 3a072807-eec0-11e6-bd65-00a098c6ed93
           Nodes Sharing the Storage Pool: cluster2-node02, cluster2-node01
          Number of Disks in Storage Pool: 3
                     Allocation Unit Size: 279.2GB
      Allocation Unit Data Size for RAID4: 186.2GB
    Allocation Unit Data Size for RAID-DP: 93.08GB
   Allocation Unit Data Size for RAID-TEC: -
                             Storage Type: SSD
                 Storage Pool Usable Size: 0B
                  Storage Pool Total Size: 1.09TB
                         Is Pool Healthy?: true
                State of the Storage Pool: normal
  Reason for Storage Pool Being Unhealthy: -
Job ID of the Currently Running Operation: -

cluster2::> storage pool show-aggregate -storage-pool ClusterCache  -instance

                     Name of Storage Pool: ClusterCache
                                Aggregate: sata_data_1
                                 Capacity: 558.5GB
Number of AU's Assigned to This Aggregate: 2
                      Original Owner Name: cluster2-node01
                                     Node: cluster2-node01

                     Name of Storage Pool: ClusterCache
                                Aggregate: sata_data_2
                                 Capacity: 558.5GB
Number of AU's Assigned to This Aggregate: 2
                      Original Owner Name: cluster2-node02
                                     Node: cluster2-node02
2 entries were displayed.

 

So, I have two nodes, two aggregate set as hybrid, 4 SSD 960GB:

storage aggregate modify -aggregate cluster4_01_NL_SAS_1 -hybrid-enabled true
storage aggregate modify -aggregate cluster4_02_NL_SAS_1 -hybrid-enabled true

 

I will create a storage pool with 3 SSD, so one remains as spare, and assign 2 AU per aggregate with raid4 type:

storage aggregate add cluster4_01_NL_SAS_1 -storage-pool StoragePool_c4_Cache1 -allocation-units 2 -raidtype raid4
storage aggregate add cluster4_02_NL_SAS_1 -storage-pool StoragePool_c4_Cache1 -allocation-units 2 -raidtype raid4

 

I prefer raid4 instead of Raid-DP in order to have more space on flash-pool.

All should works fine, correct? Any suggestions?

Thanks

TMACMD
708 Views

You are looking at two methods for FlashPool. The old method used WHOLE SSDs. The NEW method uses PARTITIONED SSDs.

 

All 4 SSDs should be modified to be "owned" by the same node.

Create the storage pool with 3 x SSDs. 

Modify the aggr to be hybrid enabled

Finally "add-disks" to each of your two AGGRs. Like you mention, use a storage-pool and specify raid4 to maximize usage.

You can only do one at a time. You need to wait for the first to finish before doing the second aggr. It will complain and not run if it is still adding-cache.

alessice
656 Views

Ok, after set as 2 the number of AU per aggregate I have add successfully the flash-pool to the two aggregates.

 

Now ONTAP but also AIQ warning me about a low number of SSD spare on node01, since of 4 SSD there is only one spare assigned to node02:

 

cluster4::> storage pool show-disks 

Storage Pool Name: StoragePool_c4_Cache1

             Disk
    Disk     Type    Usable Size  Total Size
    -------- ------- ----------- -----------
    1.0.0    SSD         894.0GB     894.3GB
    1.0.1    SSD         894.0GB     894.3GB
    1.0.10   SSD         894.0GB     894.3GB
3 entries were displayed.

cluster4::> storage aggregate show-spare-disks -disk-type SSD
                                                                      
Original Owner: cluster4-02
 Pool0
  Spare Pool

                                                             Usable Physical
 Disk             Type   Class          RPM Checksum           Size     Size Status
 ---------------- ------ ----------- ------ -------------- -------- -------- --------
 1.0.11           SSD    solid-state      - block           894.0GB  894.3GB zeroed

 

Should I change the assignment of this SSD or in case of one SSD fail, indipendentment from node01 or node02, this spare will use?

 

I remember that in the past only one SSD for spare, in Flash Pool, is safe for all nodes in HA.

 

Thanks

 

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