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DP701 slow VM restore

Hi DP-ians

Backup of VM 57GB takes 13 minutes. Restore very long (usually restore 2x of backup time. though expect disk and dedupe restore shd be faster,  but it taking longer than that)

 

DP version 701.103

 

Details :-

-Backup to internal disks with Software Dedupe catalyst enabled (backup and restore from same media)

-OS = Windows with 4 disks

-Size = 57GB

-Thick provisioned

-Backup transport = SAN (8MB disk buffer - default)

-Restore transport = SAN (1MB disk buffer - default)

-Restore using physical MA/backup host

-Full backup every day

-Snapshot disabled in VM backup config

-Existing VM renamed and powered off (delete before restore and power on selected)

 

Any further hints?

 

Other things I am planning to test are :-

1) restore via NBD (how/where to change from SAN to NBD?)

2) Play with buffer, would that help? But I have to be very careful and trying to minimze damage and take less risky options as long available

 

Thank you

 

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7 Replies
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Just find this is strange....the first disk was restored via SAN but other NDB..why and how is that?

 

Virtual Machine 'test': Restoring ...

            Disk:             scsi0:0

            Datastore:        CLONES

            Transport method: SAN

            Disk buffer:      1 MB

 

Virtual Machine 'test': Restoring ...

            Disk:             scsi0:1

            Datastore:        CLONES

            Transport method: NBD

            Disk buffer:      1 MB

 

Virtual Machine 'test': Restoring ...

            Disk:             scsi0:2

            Datastore:        CLONES

            Transport method: NBD

            Disk buffer:      1 MB

 

Virtual Machine 'test': Restoring ...

            Disk:             scsi0:3

            Datastore:        CLONES

            Transport method: NBD

            Disk buffer:      1 MB

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Admiral
Admiral

Hello,

 

a VM backup stored in a StoreOnce store is long to restore because the server need to rehydrate the data (reconstruct it) and this may take some time (specifically depending of the disk subsystem and the ressources available on the server)

Regards,

Christophe
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tried another VM restore with just 1 disk but took almost 10 hours ....size of 47GB (backup took just 5 minutes)

 

Virtual Machine 'xyz': Restoring ...

            Disk:             scsi0:0

            Datastore:        CLONES

            Transport method: SAN

            Disk buffer:      1 MB

 


However, both restored VM keep going into Windows Error Recovery screen ....not sure if this is DP restore issue or VM side...

 

 

Hi Dr.Pixel

Would it be as long as like 10 hours? It is quite bad that restore/re-hydrate from disk is at this extremely poor rate.

Is this known issue or documented? Because backup and restore expected in minutes using latest techs and also based on marketing slides 😉 ....

 

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Admiral
Admiral

Hello,

 

Well it will be difficult to compare as every environment is different.

But from my tests, I have give up to backup to a storeonce software device my VMs.

They go directly to tape. My restore is very quick.

The thruth is that I don't restore any VM because for sometime the VEAgent was driving me crazy. I had a lot of issues and the GRE is useless because of the required tasks.

Ah the greats marketing slides 😉

 

The storeonce software performance is very impacted by the underlaying hardware.

 

Oddly I've a bad performance when performing SOS on MSA/P2000 hardware instead of DAS (MSA60-P800 for example).

 

 

Regards,

Christophe
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Aaargh...those are only good in slides but not in reality...wondering why DP guys in forum havent responded...maybe they don't know either...:-D

 

Will log a support case soon....thx for your reply

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Commander Commander
Commander

Hi Thierry,

We are experiencing simillar performance issues, having very fast backups and slow restores using StoreOnce over SAN. Did you manage to resolve this?

Thank you.

Adrian

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Cadet 3rd Class
Cadet 3rd Class


@mula_e wrote:
We are experiencing simillar performance issues, having very fast backups and slow restores using StoreOnce over SAN.

What StoreOnce? With Catalyst to SO Appliances, rehydration performance is starting to get mostly reasonable with 24 spindles. SO Software on the same number of spindles is significantly slower to rehydrate (even though other factors like RAM are taken into consideration, my particular comparison box has 60GiB of it, while a typical SO Appliance has 72GiB, and CPUs are similarly beefy). SO rehydration may scale up throughput-wise if multiple objects are running in parallel (as single CPU-core throughput of the RMA is also a factor), but sadly that isnt the case when restoring a VM. Single-object rehydration can be as slow as 25MB/s. It's in the nature of the thing, sadly - rehydration is a fully random access pattern to the SO backend disks, at 4KiB blocks worst case (an SO store uses a lot of small files to stuff away individual blocks). So with less than 24 spindles, things will only deteriorate from here. I've seen SO Software on 6-disk RAIDs and they don't perform well on reading. So it all depends - what's your exact SO backend specs?

HTH,
Andre.

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