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AVVI backup direct to tape with GRT - local disk space requirements?

rablack
Level 4

Hi,

We are intending to implement a pair of ESXi servers connected to an iSCSI SAN with a third (much less powerful) server as the BE media server. An LTO-5 tape drive connected via a SAS HBA will be the backup location.

One VM will have around 700GB data on it's virtual hard disk. Most of the others will be 12GB-16GB with one or two perhaps 30GB in size.

To keep costs down for the media server, I was intending on using the smallest, cheapest disks from the vendor, since all it will need is an OS and BE installed. It will perform no other function.

What I would like to know is: If I am intending to backup my 20-30 virtual machines using the AVVI option and restore using GRT, do I need to have local storage capacity on the media server to accommodate the vmdk during a GRT restore?

Thanks,

Richard

3 REPLIES 3

Colin_Weaver
Moderator
Moderator
Employee Accredited Certified

Anything to do with GRT needs disks space for restores from tape (whichever Agent your are using)

We also higly recommend doing GRT backups to disk so that restoring one file is much much quicker.

 

Basically if your GRT backup is on disk then all we do is mount the disk image extract the file and write it back to where you want to restore to.

If however you do GRT on tape we have to recover the whole of the image (be that vmdk files for vmware or edb files etc for Exchange) and then once that is done we then have to mount the recoverd image from the staging area to pull out the file you want. this takes longer and means you will always have to keep plenty of empty disk space just for the restore.

 

Much better to have enough disk space in the first place to keep 1-2 weeks data on disk with duplication to tape for DR purposes using Incrementals to save disk space if you can.

rablack
Level 4

Hi Colin,

Thanks for your very quick and comprehensive reply. And sorry for the delay in me replying!

It sounds like no matter what, we will need at least as much disk space (somewhere) for the largest vmdk file in the event of a restore. Your suggestion of keeping 1-2 weeks data on disk is an interesting one however. Our standard practice is full backup to tape every week night with a GFS rotation. Our data is not time-sensitive, so if a restore is necessary it can almost always be done from yesterdays tape which will still be in the drive. Can you see benefits in this situation of having a "live" backup set on disk?

From the reading I have done, it also sounds like backup directly to tape may be faster than to disk then tape due to some issues with writing large files to NTFS volumes.

It may be worth noting that this backup is purely for archival purposes. User data and other live data will not be stored on the virtual machines except for one. We intend to implement twice daily snapshots within the OS of the 700GB disk and this data will also be replicated using DFS to three others sites which implement their own backup to tape solutions. It will be the snapshots that will be our primary restore medium for most files. With this in mind it seems like backup to disk is even less important in our environment. However, if you have any thoughts on this they would be greatly appreciated.

Thanks,

Richard

Colin_Weaver
Moderator
Moderator
Employee Accredited Certified

The benefits of having the live GRT set on disk are time related

Assume it takes 4 hours to restore your VMDK from tape to disk. And then a user asks for a single file restore. Which will take 4 hours plus a short bit of extra time to mount the image and extract the requested file. Imagine what then happens if the same user then says" oops - I need a different file that's the wrong one"

Now have the same backup set on disk instead of tape - you gain those 4 hours for the restore and less issues if multipel separate restores are needed.

Obviously with your other plans maybe the above scenario isn't an issue for you...