Hello @RohanS,
Please read your queries and my response in-line:
* We do not have replication, however we want to understand if taking snpashot can be a viable solution for ransomware at array end [ block level ] . or if we should be looking toward more concreate solution [ ex. Backup's / replication ]
If Ransomeware is the concern, replication will not help. Well planned backup/snapshot schedules will serve the purpose. Backups are much prefereed. (Simple snapshots in this case would be like "My server is crashed, do you have backup? Yes, I do. But it is on the server.")
* If snapshot is viable solution for ransomware in 3PAR and and if we use policy for a volume - "no_stale_ss", then will this use more space, if yes, how much ? Need some more clarification on the space consumption. [ in comparison with policy "stale_ss" ]
A systematic snapshot shedule with sufficient retention period is a viable solution as well. Here the 'no_stale_ss' policy will not impact the space consumption. The policy will just not permit the invalid/failed snapshots. Doesn't really cause higher space consumption.
* And when we set retention policy for snapshots, how will it affect space reclamation at Volume and CPG level.
As from what I know, all snapshots need to be deleted of a volume and then freespace command need to be used to free up allocated space from volume and then run compactcpg to reclaim space.
Your concern here is legitimate. It is always a trade-off where cost/efficiency on one side and capacity/performance/security on the other side. To gain a better position on security, you will have to loose a bit on space efficiency. It is all about what is most important.
So how can we take care of space reclamation when we have snapshots with retention policy.
To advise you on reclamation and retention policy, I should know on what devtype the volume is sitting and what are the other type of drives you have on the system. In general, change the copy_CPG to a CPG using low cost NL drives. Thoughtfully schedule the retention policy as per your requirement. So that you have enought snapshots covering the sufficient amount of past period, but not too many of them to consume lot of space or harming compaction efficiency.
The best practice is to set the retention period for 2-7 days, so that nobody can delete the snapshots even if they attempt during that period. And also set the auto deletion of snapshots after 5-30 days pedending on your requirement. Here, the snapshots are always secured during the retention period. And snapshots will continue to remain till auto-deletion period. But you have the option to delete snapshots post retention, prior auto-deletion. Anyway post auto deletion, snapshots will be deleted without accumulating too many of them.
Regards,
Srinivas Bhat
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I am an HPE Employee
Hi Rohan
When it comes to space reclamation for snapshots on HPE 3PAR 8440, the process differs depending on whether the volume is fully provisioned (FPVV) or thinly provisioned (TPVV).
For FPVV volumes, when a snapshot is created with a retention policy, the space consumed by the snapshot is not immediately reclaimed when the snapshot is deleted. Instead, the space is freed up gradually over time as the original data blocks are no longer needed by any remaining snapshots or host writes. This process is known as the "background copy-on-write" mechanism, and it allows space to be reclaimed automatically without requiring any manual intervention.
For TPVV volumes, the process is slightly different. When a snapshot is created, the space consumed by the snapshot is initially reserved, but it is not actually allocated until a host write occurs in that space. When the snapshot is deleted, the space is freed up immediately, and the reserved space is returned to the free pool. However, the freed-up space is not automatically reclaimed by the system. To reclaim this space, you can use the "freespace" command to instruct the system to scan the volume for unallocated space and return it to the free pool. Additionally, you can use the "compactcpg" command to optimize the space utilization of the CPG as a whole.
In your case, as you have two TPVV volumes and 20 FPVV volumes all using the same CPG, you may want to plan for space reclamation accordingly. For the TPVV volumes, you can run the "freespace" command after deleting snapshots to reclaim the space immediately. For the FPVV volumes, you do not need to run any commands, as the space will be reclaimed gradually over time. However, if you want to optimize the space utilization of the CPG as a whole, you can run the "compactcpg" command periodically to ensure that the free space is being utilized efficiently.
hope this helps.!!
Regards
Mahesh.
I work for HPE.
[Any personal opinions expressed are mine, and not official statements on behalf of Hewlett Packard Enterprise]