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seniord
Enthusiast
Enthusiast

VCB Backup of RDM - slow performance

I have been working on a customer site here with Data Protector 6.0 and ESX 3.5 using VCB 1.5.0.2192.

The client has a couple of VM file and print servers with RDM volumes of around 1TB-1.5TB.

We are using VCB file level backup and have two VCB proxy servers which will backup direct to LTO4 over the SAN. The VCB staging area is also a SAN LUN.

The problem is performance!!!. Below are the results we see based on various tests we've performed...

1. Physical environment - 4GB SAN fabric, LTO4 drives, Data Protector 6.0, SAN backup - 1.3TB of data - 3hours

2. Moving to virtual machine - 4GB SAN fabric, LTO4 drives, Data Protector 6.0, SAN backup via dedicated proxy server - 1.3TB of data, RDM in virtual mode - 10hours

Tests we perform with test data or customer data, we seem to consistently be getting 200GB per hour with VCB however the 10 hour backup only equates to just over 100GB per hour which is even worse.

I would like to understand why we are seeing this bad performance. I know performance is not straight forward but it would point to the overheads with VCB as to why its a lot worse that conventional physical server backup. We have stress tested the VCB proxy and we can backup 130GB in 10mins outside of VCB using optimised (3:1 compression) data.

Would appreciate any comments or suggestions in regards to RDM backups via VCB.

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Rajeev_S
Expert
Expert

Hi,

I'm struck with the same issue. Backups of RDM is slow,, but data in VMFS volumes can be backed up fastly with good transfer rate.

Did you find any sloution?

Anyone has any ideas or suggestion.

Appreciate your help.

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The_Bublitz
Contributor
Contributor

We're also having issues with VCB backing up an RDM. Backing up image level on other servers takes 10-20 minutes, but we have one RDM that takes 4+ hours. There are only 2 gigs of actual data on the disk, but it seems like it pushes all 1TB of the RDM. Is VCB not intelligent enought to backup data on RDM's without making a copy of the whole physical drive first?

Any help is also appreciated.

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jbrazio
Enthusiast
Enthusiast

Hello,

I had a similiar issue with a MSA1500 in a active/passive setup, I found out that the ESX hosts were not using the fibre path to active controller on the MSA but instead the path to the passive controller.

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seniord
Enthusiast
Enthusiast

After a long running VMware support call was finally closed, we were advised that the expected throughput for a VCB server is 40 MB/s from the proxy server to the LUN. Specific details regarding what limits this speed were not provided.

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dconvery
Champion
Champion

Sorry, I missed your original post. The limitation on speed has something to do with the CMD.EXE copy function. If you just use a cmd line and perform a simple file copy, it is relatively slow, I can get about 1GB per minute. If you use windows explorer, it will scream. Go figure.

Dave Convery

VMware vExpert 2009

Careful. We don't want to learn from this.

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Dave Convery, VCDX-DCV #20 ** http://www.tech-tap.com ** http://twitter.com/dconvery ** "Careful. We don't want to learn from this." -Bill Watterson, "Calvin and Hobbes"
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