So if you purchased a Equallogic and put it into production one of the first things that you notice is that your xTB didn’t go as far as you originally planned, this is because Equallogic by default comes with a 100% snapshot reserve on all volumes that you create. This means that if you allocate a 1TB LUN, then the system provisions 1TB of LUN space and an additional 1TB of snapshot reserve for this LUN. This is neither good nor bad. However this is not always necessary. If you plan on making little use of snapshots you may want to decrease this amount of reserve or in my case remove it entirely (as we don’t plan on using it at all).
Examine the Pool and the Existing Free Space and Capacity
Notice that we get two different results with regard to FreeSpace. This is because the “pool show” command will deduct the snap-reserves of all allocated volumes and thus show us the actual usable space for provisioning a new volume. Alternatively “member show -poolinfo” will leave the snapshot reserve space unless it is actually written, so basically we have our 363GB + 2TB in reserves – actual space used by snapshots (in this case 551GB).
SANGroup00> pool show Name Default Members Volumes Capacity FreeSpace -------------------- ------- ------- ------- ---------- ---------- default true 1 2 4.35TB 363.22GB SANGroup00> member show -poolinfo Name Status Version Disks Capacity FreeSpace Connections Pool ---------- ------- ---------- ----- ---------- ---------- ----------- ------- EQL00 online V5.1.1 (R1 12 4.35TB 1.89TB 24 default 85010)
Show Existing Configuration of the First Volume
Now in the below output we are looking at the configuration of Volume00. We want to notice, the snap-reserve, snap-reserve-available, and snapshots field. You will see that in my example we have a 100% reserve (which is default) and that we have 54% of that snap-reserve available. This means that we have snapshots in the snapshots field, and that we are using some of that space (which means part of it is no longer “reserved”).
SANGroup00> volume select Volume00 SANGroup00(volume_Volume00)> show _____________________________ Volume Information ______________________________ Name: Volume00 Size: 1TB VolReserve: 1TB VolReserveInUse: 492.7GB ReplReserveInUse: 0MB iSCSI Alias: Volume00 iSCSI Name: ActualMembers: 1 iqn.2001-05.com.equallogic:8-cb2b76- Snap-Warn: 10% a51cd9059-188000000244f04f-volume00 Snap-Depletion: delete-oldest Description: Snap-Reserve: 100% Snap-Reserve-Avail: 54% (551.86GB) Permission: read-write DesiredStatus: online Status: online Connections: 8 Snapshots: 1 Bind: Type: not-replicated ReplicationReserveSpace: 0MB Replicas: 0 ReplicationPartner: Pool: default Transmitted-Data: 1011.65GB Received-Data: 3.15TB Pref-Raid-Policy: none Pref-Raid-Policy-Status: none Thin-Provision: disabled Thin-Min-Reserve: 0% (0MB) Thin-Growth-Warn: 0% (0MB) Thin-Growth-Max: 0% (0MB) ReplicationTxData: 0MB MultiHostAccess: enabled iSNS-Discovery: disabled Replica-Volume-Reserve: 0MB Thin-Clone: N Template: N NAS File System: N Administrator: Thin-Warn-Mode: offline _______________________________________________________________________________
Remove the Snapshot from the First Volume
The snapshot we have will no longer be needed so we are getting rid of that now.
SANGroup00(volume_Volume00)> snapshot show Name Permission Status Schedule Connections --------------------------- ---------- ----------- -------- ----------- Volume00-2012-01-04 read-write offline 0 -20:20:43.3.1 SANGroup00(volume_Volume00)> snapshot delete Volume00-2012-01-04-20:20:43.3.1 Do you want to delete the snapshot? (y/n) [n]y Snapshot deletion succeeded.
Modify the Existing Snap-Reserve of the First Volume
I am removing the snap-reserve in its entirety. If you simply want to decrease the space available for snapshots use an appropriate percentage.
SANGroup00(volume_Volume00)> snap-reserve 0%
Review Configuration of First Volume
Make sure everything looks right before moving on.
SANGroup00(volume_Volume00)> show _____________________________ Volume Information ______________________________ Name: Volume00 Size: 1TB VolReserve: 1TB VolReserveInUse: 492.77GB ReplReserveInUse: 0MB iSCSI Alias: Volume00 iSCSI Name: ActualMembers: 1 iqn.2001-05.com.equallogic:8-cb2b76- Snap-Warn: 10% a51cd9059-188000000244f04f-volume00 Snap-Depletion: delete-oldest Description: Snap-Reserve: 0% Snap-Reserve-Avail: 0% (0MB) Permission: read-write DesiredStatus: online Status: online Connections: 8 Snapshots: 0 Bind: Type: not-replicated ReplicationReserveSpace: 0MB Replicas: 0 ReplicationPartner: Pool: default Transmitted-Data: 1015.44GB Received-Data: 3.15TB Pref-Raid-Policy: none Pref-Raid-Policy-Status: none Thin-Provision: disabled Thin-Min-Reserve: 0% (0MB) Thin-Growth-Warn: 0% (0MB) Thin-Growth-Max: 0% (0MB) ReplicationTxData: 0MB MultiHostAccess: enabled iSNS-Discovery: disabled Replica-Volume-Reserve: 0MB Thin-Clone: N Template: N NAS File System: N Administrator: Thin-Warn-Mode: offline _______________________________________________________________________________
Show Existing Configuration for the Second Volume
Check our snap-reserve, snap-reserve-avail, and snapshots.
SANGroup00> volume select Volume01 SANGroup00(volume_Volume01)> show _____________________________ Volume Information ______________________________ Name: Volume01 Size: 1TB VolReserve: 1TB VolReserveInUse: 875.07GB ReplReserveInUse: 0MB iSCSI Alias: TestDS iSCSI Name: ActualMembers: 1 iqn.2001-05.com.equallogic:8-cb2b76- Snap-Warn: 10% 8cecd9059-2b20000000b4ec1a-volume01 Snap-Depletion: delete-oldest Description: Snap-Reserve: 100% Snap-Reserve-Avail: 100% (1TB) Permission: read-write DesiredStatus: online Status: online Connections: 8 Snapshots: 0 Bind: Type: not-replicated ReplicationReserveSpace: 0MB Replicas: 0 ReplicationPartner: Pool: default Transmitted-Data: 5.46TB Received-Data: 7.77TB Pref-Raid-Policy: none Pref-Raid-Policy-Status: none Thin-Provision: disabled Thin-Min-Reserve: 0% (0MB) Thin-Growth-Warn: 0% (0MB) Thin-Growth-Max: 0% (0MB) ReplicationTxData: 0MB MultiHostAccess: enabled iSNS-Discovery: enabled Replica-Volume-Reserve: 0MB Thin-Clone: N Template: N NAS File System: N Administrator: Thin-Warn-Mode: offline _______________________________________________________________________________
Modify the Existing Snap-Reserve for Second Volume
Again simply removing the snap-reserve.
SANGroup00(volume_Volume01)> snap-reserve 0%
Review Configuration of Second Volume
Sanity check our changes to the second volume.
SANGroup00(volume_Volume01)> show _____________________________ Volume Information ______________________________ Name: Volume01 Size: 1TB VolReserve: 1TB VolReserveInUse: 875.07GB ReplReserveInUse: 0MB iSCSI Alias: TestDS iSCSI Name: ActualMembers: 1 iqn.2001-05.com.equallogic:8-cb2b76- Snap-Warn: 10% 8cecd9059-2b20000000b4ec1a-volume01 Snap-Depletion: delete-oldest Description: Snap-Reserve: 0% Snap-Reserve-Avail: 0% (0MB) Permission: read-write DesiredStatus: online Status: online Connections: 8 Snapshots: 0 Bind: Type: not-replicated ReplicationReserveSpace: 0MB Replicas: 0 ReplicationPartner: Pool: default Transmitted-Data: 5.46TB Received-Data: 7.77TB Pref-Raid-Policy: none Pref-Raid-Policy-Status: none Thin-Provision: disabled Thin-Min-Reserve: 0% (0MB) Thin-Growth-Warn: 0% (0MB) Thin-Growth-Max: 0% (0MB) ReplicationTxData: 0MB MultiHostAccess: enabled iSNS-Discovery: enabled Replica-Volume-Reserve: 0MB Thin-Clone: N Template: N NAS File System: N Administrator: Thin-Warn-Mode: offline _______________________________________________________________________________
Examine the Pool and the New Free Space and Capacity
Now we should notice a significantly different FreeSpace indications on both commands, and they should match if you disabled all snap-reserves on all volumes.
SANGroup00> pool show Name Default Members Volumes Capacity FreeSpace -------------------- ------- ------- ------- ---------- ---------- default true 1 2 4.35TB 2.35TB SANGroup00> member show -poolinfo Name Status Version Disks Capacity FreeSpace Connections Pool ---------- ------- ---------- ----- ---------- ---------- ----------- ------- EQL00 online V5.1.1 (R1 12 4.35TB 2.35TB 24 default 85010)
Configure the Default Snap-Reserve
Of course if you don’t already have a bunch of volumes on which to make this change you can always just change the default behavior. Then all subsequently created volumes will have a snap-reserve of whatever you have picked.
SANGroup00> grpparams def-snap-reserve 0%