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OBi
Novice
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Is it possible to make a redundant array of independent memory (RAIM) at Pmem?

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Emeth_O_Intel
Moderator
263 Views

Hello OBi,

 

I would like to provide you more information about your questions:

 

1. Is it possible to make a redundant array of independent memory (raim) when using dc persistent memory as ram?

|->> Sorry, I am still checking this information in order to provide you the most accurate details.

 

2. Is it possible to make a redundant array of independent disk (raid) if they use it as storage?

|->> see following info about RAID:

 

Availability across NUMA nodes within the same physical system can be implemented through software RAID.

Use Linux Volume Manager, mdadm, and device-mapper to mirror, stripe, or concat data across the NUMA nodes.

However, this approach does not protect against a server/node outage.

 

Additionally, The DCPMM could be configured in AppDirectNotInterleaved. SW RAID could then be configured per NUMA, or across NUMA, to protect against a single DCPMM failure. Again, no node failure protection.

 

Note that only stripe, concat, and mirror support DAX. RAID4/5/6 do not.

 

Also, I would like to share some useful links:

 

 

RDMA approach should be useful. However, applications must implement this feature to ensure they push data to another node. PMDK has librpmem which allows developers to implement a simpler RDMA replication approach at the persistent memory pool level. Writes to a local pool are automatically replicated to another memory pool on another server or servers. Code development is required though.

 

As soon as I will have more details about the RAIM, I will be posting the updates.

 

Have a great day.

 

Regards,

 

Emeth O.

Intel® Server Specialist 

A Contingent Worker at Intel.

View solution in original post

12 Replies
Emeth_O_Intel
Moderator
262 Views

Hello OBi,

 

Thank you for contacting Intel® Optane™ DC Persistent Memory Community Support.

 

I will be more than happy to assist you with this, but also I would like to gather more details about this project you are implementing. Could you please so kind and provide me more details about it?

 

On the other hand, we have a feature called: The libpmemblk library.

 

This feature implements a pmem-resident array of blocks, all the same size, where a block is updated atomically with respect to power failure or program interruption (no torn blocks). This library is provided for cases requiring large arrays of objects at least 512 bytes each.

 

If you would like to see more details about how to implement the feature please check the following link below:

 

 

Also, it will be very important to have some background using the programming with Intel® Optane™ DC Persistent Memory.

If you would like to have more details about the Persistent Memory Programming, I would like to refer you to the following links:

 

  1. What is Persistent Memory: Persistent Memory Programming Series.
  2. Introduction to Programming with Intel® Optane™ DC Persistent Memory
  3. Persistent Memory Development Kit (PMDK) Introduction.

 

If you have more questions or additional information to share. Please do not hesitate and let me know and I will be more than happy to assist you.

 

Have a great day.

 

Best regards,

 

Emeth O.

Intel® Server Specialist 

A Contingent Worker at Intel.

OBi
Novice
262 Views

Hi Emeth, thanks for your answer.

We are currently planning our new storage and server structure. dc persistent memory attracted our attention and we are wondering if it can be used in our new structure. Some of the questions that come to our mind are; Is it possible to make redundant array of independent memory (raim) when using dc persistent memory as ram? or Is it possible to make a redundant array of independent disk (raid) if you we use it as a storage?

Emeth_O_Intel
Moderator
262 Views

Hello OBi,

 

Thank you so much for all the details provided.

 

Let me verify those details in order to provide you the most accurate information.

 

As soon as possible I will be contacting you back in order to proceed with the next step.

 

Best regards,

 

Emeth O.

Intel® Server Specialist 

A Contingent Worker at Intel.

Emeth_O_Intel
Moderator
264 Views

Hello OBi,

 

I would like to provide you more information about your questions:

 

1. Is it possible to make a redundant array of independent memory (raim) when using dc persistent memory as ram?

|->> Sorry, I am still checking this information in order to provide you the most accurate details.

 

2. Is it possible to make a redundant array of independent disk (raid) if they use it as storage?

|->> see following info about RAID:

 

Availability across NUMA nodes within the same physical system can be implemented through software RAID.

Use Linux Volume Manager, mdadm, and device-mapper to mirror, stripe, or concat data across the NUMA nodes.

However, this approach does not protect against a server/node outage.

 

Additionally, The DCPMM could be configured in AppDirectNotInterleaved. SW RAID could then be configured per NUMA, or across NUMA, to protect against a single DCPMM failure. Again, no node failure protection.

 

Note that only stripe, concat, and mirror support DAX. RAID4/5/6 do not.

 

Also, I would like to share some useful links:

 

 

RDMA approach should be useful. However, applications must implement this feature to ensure they push data to another node. PMDK has librpmem which allows developers to implement a simpler RDMA replication approach at the persistent memory pool level. Writes to a local pool are automatically replicated to another memory pool on another server or servers. Code development is required though.

 

As soon as I will have more details about the RAIM, I will be posting the updates.

 

Have a great day.

 

Regards,

 

Emeth O.

Intel® Server Specialist 

A Contingent Worker at Intel.

View solution in original post

OBi
Novice
262 Views

Thanks Emeth,

waiting for details about raim.

Emeth_O_Intel
Moderator
262 Views

Hello OBi,

 

Thank you so much for your time.

 

The information I found is that if you are going to use this feature in Memory Mode, this is not possible.

We configure all DCPMM in an interleaved set, and there's no option to change this.

 

Additions regarding RAID info previously provided. Internal testing reveals performance numbers are not as expected.

Intel is working to improve this feature using the Intel® Optane™ DC Persistent Memory.

 

Have a wonderful day.

 

Emeth O.

Intel® Server Specialist 

A Contingent Worker at Intel.

 

 

OBi
Novice
262 Views

Hi Emeth,

thanks for your answers and effort.

Emeth_O_Intel
Moderator
262 Views

Hello OBi,

 

No problem, if you have more questions, or need additional information, don't hesitate to let us know and we will be more than happy to assist you.

 

Have a wonderful day.

 

Regards,

 

Emeth O.

Intel® Server Specialist 

A Contingent Worker at Intel.

 

OBi
Novice
262 Views

One more question;

Is there any backup space on the dc persistent memory like enterprise ssd? Does it transfer the information to this backup area when there is a corruption in the chips?

Emeth_O_Intel
Moderator
262 Views

Hello OBi

 

Let me say that it is possible to configure DCPMM to RAID5/6. As previously stated, the performance have been lacking, and we don't recommend it.

 

Regards,

 

Emeth O.

Intel® Server Specialist 

A Contingent Worker at Intel.

Emeth_O_Intel
Moderator
262 Views

Hello OBi,

 

I am following up on your thread in order to verify if there is anything else I can help you with?

if so, please do not hesitate and let me know and I will be more than happy to assist you.

 

Regards,

 

Emeth O.

Intel® Server Specialist 

A Contingent Worker at Intel.

 

Emeth_O_Intel
Moderator
262 Views

Hello OBi,

 

Due to the fact that I have not seen any activity recently, I will proceed and mark this thread as completed.

 

Please if you have more questions do not hesitate and contact us back and I will be more than happy to assist you.

 

Best regards,

 

Emeth O.

Intel® Server Specialist 

A Contingent Worker at Intel.

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