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problems with the size of the snapshots in msa 2040/50

 
EduRuizBlas
Occasional Contributor

problems with the size of the snapshots in msa 2040/50

Well, I'm having problems with snapshot management in several msa cabins 2042 and 2052, I'm in 10 Tb luns every snapshot 1 Tb consumes me and I fill the storage quickly. I leave a policy of retention of 5 points of restoration.
9 REPLIES 9
Shawn_K
HPE Pro

Re: problems with the size of the snapshots in msa 2040/50

Hello,

I must confess I am not fully understanding your post. Perhaps if you provide a little more detail we can help you figure this out. Also, please state whether you are using virtual or linear storage on the MSA2042. I know it has to be virtual on the MSA2052.

From what I do understand, it sounds as if you have 10TB LUNs. You need to consider how much data each volume has and how much free space in on the Pool. Also, remember that virtual replication has internal snapshots and you need to account for that space. If you are using fully provisioned Pools, your snapshots will be fully provisioned as well.

The MSA allows you to set certain threshold policies. Depending on the thresholds and available space left in the pool, will determine how many snapshots you can retain.

If you are taking 1TB snapshots then calaculate how much space is being consumed in the base volume, how much space the internal shapshots will consume, and how many snapshots you are retaining. If the available snapshot space limit is being exceeded, you may need to consider adding another disk-group to the pool or reconfiguring your snapshot and replication plan.

I am not understanding your reference to leaving a policy of retention of 5 points of restoration. If you are retaining 5 snapshots to restore from you may want to consider dropping the snapshot retention limit. Remember that for virtual replication there are hidden snapshots that do consume space. You can view the snapshots and their space more correctly in the CLI than in SMU.

Please provide more details if I have not answered your questions.

Cheers,
Shawn

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EduRuizBlas
Occasional Contributor

Re: problems with the size of the snapshots in msa 2040/50

Thank you very much, sorry for not being more specific. My problem is that I have a Lun in virtual mode of 10 Tb and I detect that each snap consumes 10% of the size. when the 5 instantaneous ones are generated, the storage is left without space, causing the cabin to fall. I do not know if I am doing wrong with the snap shots configuration since I find it excessive to use the volume for each snap

Re: problems with the size of the snapshots in msa 2040/50

1st of all you haven't mentioned total Pool size

How many volumes are part of that Pool

How much % allocated for snapshot

Have you checked if "overcommit" option disabled or enabled in the Pool ? 

Any replication got configured in the same Pool?

We need to understand rate of change of your data and based on that you should fix retention count, adjust snapshot space and thresholds.

As MSA2050 snapshot technology works with Redirect-On-Write (ROW)  so we need to understand how much is unique data and how much is shared data accross the volume and his snapshots.

In your case you have 10TB LUN but we don't know how much data actually there in that volume. You have mentioned each snapshot is 1TB space consuming which is really very high. Ideally unique data can be in MBs because change of data generally like that only. Winout more details or logs it's difficult to say what exactly happening here.

I hope you have set the snapshot-space management policy as automatic deletion when retention count reached.

 

Hope this helps!
Regards
Subhajit

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EduRuizBlas
Occasional Contributor

Re: problems with the size of the snapshots in msa 2040/50

Good, attached cabin configuration image

Re: problems with the size of the snapshots in msa 2040/50

Good to see the picture but I need more details. Can you please provide the below command outputs,

show pools
show disk-groups
show snapshot-space
show snapshots type all
show volumes

 

Hope this helps!
Regards
Subhajit

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Shawn_K
HPE Pro

Re: problems with the size of the snapshots in msa 2040/50

Hello,

The Pool shows a total space of 13.3TB, 2220GB of reserved space and allocated space of 11.5TB. This is leaving you 1.8TB of free available space. If as you say you are taking 1TB snaps there is not enough free space for you to take snaps when you take into consideration the snap and unseen/hidden snap.

If your allocated space is this large you are going to need to add more drives in order to add additional disk-groups to give you the needed space to take snaps.

Cheers,

Shawn

 

 

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EduRuizBlas
Occasional Contributor

Re: problems with the size of the snapshots in msa 2040/50

good again, attached screenshot of the requested commands
 

Re: problems with the size of the snapshots in msa 2040/50

So you have Pool Size: 13.3TB and Volume also 13.3TB provisioned size but actual actual data or allocated 11.5TB. For snap 1338.2GB limit set which is very less.

Now only 1.8TB of space available in the Pool and if you take one snapshot of 11.5TB of data then in next snapshot if any data change is there then almost 1TB space of the Pool eaten up by snap according to you. (I can't verify this as there is no snapshot was present when you have captured the screenshots)

Imagine the situation when Volume allocation space will increase with new data writes and it may touch around 13TB which is almost equal to Pool space then how will you take Snapshot?

So you are lack of space in this system to achieve retention count of 5

 

 

Hope this helps!
Regards
Subhajit

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Re: problems with the size of the snapshots in msa 2040/50

@EduRuizBlas..................do you have any update or outstanding query?

Request you to please update on the forum so that everyone can get the update who are all following.

If you have no further query and you are satisfied with answers then kindly mark the forum as resolved.

 

Hope this helps!
Regards
Subhajit

If you feel this was helpful please click the KUDOS! thumb below!

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