03-07-2018 04:38 AM
I have a client who has the following environment:
1 x Windows Master Server - 8.0
1 x 5220 Appliance - 3.0
1 x EMC VNX Storage Array (compression and de-duplication enabled)
We have been backing up data from the VNX (FC SAN attached to 5220 appliance) for some time - successfully and getting a 90%+ de-dup rate on the appliance.
The VNX contains approximately 12TB of data (raw) which after compression / de-duplication is occupying approx 5.2TB on the VNX.
The backup runs and the detail of the NBU joblog reports that it transfers approx 5.2TB for a full NDMP backup.
We have then introduced a Dell/EMC Unity storage array - 10GbE and FC attached (same as the VNX). The Unity array does not support de-duplication yet so data is being stored compressed ONLY. Same amount of data (copied from the VNX) is resident - 12TB raw which is being compressed and occupies approx 5.8TB.
NBU joblog for the VNX NDMP backup shows the following:
server_archive: emctar vol 1, 20329641 files, 0 bytes read, 5280829065761 bytes written
StorageServer=PureDisk:xx-5220mstr-01; Report=PDDO Stats (multi-threaded stream used) for (xx-5220mstr-01): scanned: 5160695488 KB, CR sent: 78000493 KB, CR sent over FC: 0 KB, dedup: 98.5%, cache hits: 946829 (1.5%), rebased: 1041309 (1.7%)
NBU joblog for the Unity NDMP backup shows the following:
server_archive: emctar vol 1, 20468795 files, 0 bytes read, 12551838453045 bytes written
StorageServer=PureDisk:xx-5220mstr-01; Report=PDDO Stats (multi-threaded stream used) for (xx-5220mstr-01): scanned: 12260510921 KB, CR sent: 12089125062 KB, CR sent over FC: 0 KB, dedup: 1.4%, cache disabled
Our issue is as follows:
Why is the VNX transferring 5.2TB of data for a full backup and the Unity transferring 12TB for a full backup ?
We have a support call open with Veritas on this but are being told this is working as designed...... They are saying that it is a Dell/EMC issue. I believe that NBU does NOT have a stream handler for the latest implementation of NDMP on the Dell/EMC Unity array running with a UFS64 filesystem.
Confusing statement from Veritas is:
We uncompress/re-hydrate the data before sending to the appliance for backup when backing up ANY array (not just EMC). If this is the case then why are we seeing 5.2TB being transferred from the VNX and 12TB transferred from the Unity ?
Is anyone else backing up data from a Dell/EMC Unity array into Netackup, and if so are you getting good de-duplication rates on the appliance ?
The Unity in question is:
Array Model: Unity 350F - Dual SP
Software Revision: 188.8.131.5235982 184.108.40.20635982
SP Memory: 49152 49152
Write Cache State: ENABLED ENABLED
Write Cache Size: 5587 MB 5587 MB
SP Fault LED: OFF OFF
Enclosures: 1 1
Disks: 22 22
Any input appreciated.
03-09-2018 01:29 AM
Root cause of difference in amount of data being sent here is that the Unity is uncompressing data before sending it, VNX is sending de-duped / compressed data. This is down to a difference in where the data is compressed / de-duped. On the VNX it is done at the file-system level, on the Unity it is done at the LUN Pool level (hence the file-system knows nothing about the compression / de-dup status).
Also - when the data arrives at the appliance NBU has an NDMP stream handler for the VNX whereas it does not for the Unity. Therefore - it cannot interpret the contents of the NDMP stream from the unity and we get very low de-dup rates.
I am currently testing a CIFS type backup of the data to determine if this will return better de-dup results - but this will still involve transmitting all of the data to the appliance (12TB) as opposed to 5.6TB