2010-01-15 04:29 PM
Hi everyone, we are evaluating having a second filer at a DR site and using all of the Netapp tools such as SnapMirror, SMVI, SnapManager for Exchange, SnapManager for SQL. My question is, do I really need to continue to backup everything to tape if I have two copies of everything already along with the snapshots for going back in time? If someone has any experience running tapeless, I would be very interested.
2010-01-16 06:09 AM
We have 3 sites. Two are linked by snapmirror and we keep two weeks of snapshots on these systems. If we ever had a service failure we move the service (Exchange, SQL, vmware or CIFS) between the sites by breaking the mirrors and making the 2nd site production. The 3rd site is then used as a snapvault destination and keep two years of weekly snapshots.
However - Yes we still use tape!
Tapes are copies of the data from within the snapvaults and they are created once a month and stored with a 3rd party offsite. This is because we have to keep the data for either 5, 7 or 20 years, dependant on the app which created it.
Hope this helps.
2010-01-16 06:12 PM
Thanks Brendon for your insight, sounds like if you need to store your data for longer period of time, tape is still the answer. We only need 7 years where I work, after that not needed. Anyone else like to comment?
2010-01-17 08:27 AM
My concern with that is that I would not trust tape for more than about 5 years. 7 maybe and certainly not 20 unless I had a tape refresh program in place.
2 reasons for this. One is that tape is magnetic and breaks down over time and will do so silently. The other is let's think about what kind of tape drives we were all using in 1990. Do you still have them around? Do you know they still work? Could you get parts if they didn't?
It's the old IT saying, "Backups are worthless. Restores are golden"
The cost between big SATA disks and tape are getting closer together. When you consider the time and expense of a tape refresh program, they get really close. Say what you want about disk, but I can scan it regularly and check for media errors. I can implement WORM so that the data cannot be altered. If I really want to be sure I can get 20 year old data back under penalty of law, I want disk.
Just one guy's opinion...
-- Adam Fox
2010-01-19 07:42 AM
We keep tapes as well. It's too easy to delete a volume and loose your snaps
hots. I've been known to delete something that I didn't mean to before. Plus, if there ever was a disgruntaled admin, they could likely cause havock on a system. That said, our tape process is now a weekly ordeal.
I just priced an LTO3 tape library with 12 slots for $3100, plus $1000 for 20 tapes. Throw in another $1000 or so for a scsi card for the filer. A very small price to pay for an extra set of offline backup!
2010-01-19 08:14 AM
I completely agree with Adam's comments about a tape refresh program and restores being golden.
One other thing I would add is that calculating your capacity for disk is not just related to your retention period but your rate of change in the data.
Now that ONTAP 7.3 supports de-dupe of snapvault destinations you have the potential to save space in your disk based backup but you have some constraints to deal with.
Remember that until larger aggregates are available, your maximum storage pool you can use for snapvault data will be 16TB without having to re-baseline your disk based backup. You need to factor that into any capacity planning calculations.
2010-01-19 08:33 AM
It's too easy to delete a volume and loose your snapshots. I've been known to delete something that I didn't mean to before. Plus, if there ever was a disgruntaled admin, they could likely cause havock on a system.
The first two things can be mitigated by using SnapVault - deleting primary snaps / volumes doesn't affect secondary.
The third one can be addressed by combining SnapVault with SnapLock.
Tapes can be destroyed too (accidentally or purposely)