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Ask the Expert Summary: New Data Domain system introduction

Ask the Expert Summary: New Data Domain system introduction

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Introduction

This article summaries the Chinese ATE activity: New Data Domain system introduction. The original thread is https://community.emc.com/thread/196489

Detailed Information

Question1: Could you please provide the Data Domain (DD) RAM memory capacity of the various types of Data Domain?

Answer:

·         DD2200 supports 2 x 4 GB or 4 x 4 GB memory DIMMs

·         DD2500 supports 4 x 8 GB or 8 x 8 GB memory DIMMs.

·         DD4200 supports 16 x 8 GB memory DIMM.

·         DD4500 supports 8 x 8 x 16 GB and 8 GB memory DIMM. DIMMs must be in the specified slot.

·         DD7200 supports 128 GB 8 x 16 GB DIMMs and retain 8 free slots.

·         DD7200 support 256 GB memory and includes 16 x 16 GB DIMMs.

Please refer to the Administrator's Guide for the specific memory slot information.

Data Domain DD2200 and DD2500 Systems Hardware Overview

https://support.emc.com/docu51556_Data_Domain_DD2200_and_DD2500_Systems_Hardware_Overview.pdf?langua...

Data Domain DD4200, DD4500, and DD7200 Hardware Guide

https://support.emc.com/docu50992_Data_Domain_DD4200,_DD4500,_and_DD7200_Hardware_Guide.pdf?language...

Question2: Data Domain has file system sharing features. So, what is the difference of file system sharing between Data Domain and traditional NAS devices?  What kind of considerations does one have to consider due to the adding the file system sharing features on the deduplication devices?

Answer: Data Domain provided CIFS/NFS function is consistent with traditional NAS devices. However DD is designed for backup and recovery solution system, we encourage customers to backing up their data to DD share devices. Using the CIFS/NFS feature of Data Domain can leverage the customer's existing IP network environment, and you don't need to buy additional Data Domain license. When the host writes data to Data Domain via the CIFS/NFS protocol, all data is transferred over the network to the Data Domain, and then written to disk after compression.

CIFS/NFS configuration on Data Domain, please refer to Data Domain Administrator's Guide, for example

EMC Data Domain Operating System Version 5.4 Administration Guide

https://support.emc.com/docu50994_Data-Domain-Operating-System-Administration-Guide-5.4.pdf?language...

Question3: Please provide the hardware information of the new Data Domain series. For example, what type of disc is supported, what kind of extended Cabinet and how many cabinets will be supported?

Answer: For hardware specific information, please refer to the hardware manual.

Data Domain DD2200 and DD2500 Systems Hardware Overview

https://support.emc.com/docu51556_Data_Domain_DD2200_and_DD2500_Systems_Hardware_Overview.pdf?langua...

Data Domain DD4200, DD4500, and DD7200 Hardware Guide

https://support.emc.com/docu50992_Data_Domain_DD4200,_DD4500,_and_DD7200_Hardware_Guide.pdf?language...

Question4: Are the 6 series and 8 series of Data Domain have been discontinued? What is the enhancement of new Data Domain compared to the previous generation Data Domain?

Answer: Data Domain 6 series and 8 series are still being supported.

New Data Domain products have been enhanced on both hardware and software. On the software, the new Data Domain equipped with the latest DDOS 5.4 (Refer to 5.4 Administrator reference manual for details). On the hardware, the new Data Domain used a unified EMC SP instead of the previous chassis. Internal components are completely modularity, so user or site engineer can easy to replace modules without having to open the chassis.

Question5: How many types of head disks does Data Domain have for OS installation?

Answer: Data Domain has two types.

One is DLH (Data Less Head): Head disks only store the OS and do not store the data.

Another is the AIO (All In One): Head disk used to store OS and also used for storing the data. Each disk has multiple partitions, and have a specific partition is available for the DDOS, another for data storing.

Question6: Will the DDOS be distributed store on the all of the Data Domain disks? I remember there is one way to store the DDOS to a CF card, right? Also please provide some documentation about DDOS.

Answer: You mentioned CF card is DOM (Disk On Module). Before the DDOS 4.7, Flash DOM card as the default boot device. Even before the DDOS 4.7, head disks also installed DDOS. When DOM card cannot be used, we can modify the boot option, and then boot from internal hard drive and enter to the DDOS. In the DDOS version 4.7 and higher, DOM card is no longer required.

Both AIO and the DLH, specific partitions in your head disk is use for DDOS. DDOS mirrored in the head disks, it is based on EXT3. DDOS also has high redundancy.

Please refer to the DDOS 5.4 Administrator's Guide for DDOS introduction

https://support.emc.com/docu50994_Data_Domain_Operating_System_Administration_Guide_5.4.pdf?language...

Question7: Could you introduce the replication in two Data Domains? The replication for single tape drives, folders and entire file system.

Answer: Data Domain replication has three types. They are Directory, Mtree and Collection.

Directory replication is based on the file as a unit. Directory replication will copy the subdirectories which are under the /data/col1/backup of the source Data Domain to the /data/col1/backup of the destination Data Domain.

Mtree replication is based on the snapshot as a unit. Mtree replication will copy the /data/col1/< non-backup_mtree> of the source Data Domain to the /data/col1/< non-backup_mtree> of destination Data Domain.

Collection replicationis based on the file system as a unit. Collection replication will copy the data of the source Data Domain to the destination Data Domain.

Question8: If I want to make tape replication, is there a better solution?

Answer: A Data Domain virtual tapes is stored on the file system in file format. But on Data Domain replication, Data Domain virtual tape is coped in pool as a unit.

For example, the Default pool has 100 virtual tapes and each tape size is 200GB. So, if replicate Default pool, it will copy the 100 files to the destination of Data Domain.

If the path of Default pool is /data/col1/backup/vtc/Default, the corresponding replication is Directory replication.

If the path of Default pool is /data/col1/Default, the corresponding replication is Mtree replication.

The users can freely select the tape they want to replicate. If an A1000L3 of Default pool is does not need to be replicated, it can be moved to a Vault or other pool which is not configured for replication. The specific process is export A1000L3 from Default to Vault, then import into another pool.

Question9: What are the conditions for trigger replication? What is the update cycle for replication?

Answer: For Mtree replication, if the synchronization is completed, the source Data Domain will generate a snapshot in every 15 minutes and compare with the destination Data Domain.

Directory replication use replication.log to record the file changes of source Data Domain. Then, according to the replication.log, sequentially copy the file changes to the destination Data Domain.

Collection replicationis directly copy the file system changes to destination Data Domain in real time.

Question10: Data Domain could provide both CIFS and NFS. So, could we mix use CIFS and NFS in the same directory?

Answer: We do not recommend mixing in same directory with CIFS and NFS. For details, please check EMC KB181533.

Managing User Permissions on the Data Domain System Data Domain/EMC does not recommend to backup NFS and CIFS files to the same directory. https://support.emc.com/kb/181533

Question11: Please explain the storage mechanism of Data Domain metadata.

Answer: About how Data Domain metadata is stored, it is same with the method of storing RAID6 data. In simple terms, metadata will be stored on RAID6 stripe after the slicing and deduplication. 

                                                                                                                                              

Author: Leo Li

          

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