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Online Backup vs. Tape Backup?
hashbox asks: "I work for a small non-profit (about 100 staff members) and management has decided that they want to use an online data backup system instead of our existing tape backup system. After a meeting with one of the many vendors providing this service, I must admit that I am impressed with the promise of the technology (ease of use etc). However the sysadmin side of me has a few reservations. Has anyone here on Slashdot used an online backup service, and what were your experiences?"
Good point there. Use the offsite for disaster recovery and local backup for risk mitigation. What I never understood with the offsite solution is the time. Most smaller companies only have a 1.5Mbps connection. That first backup's going to be massive as will the daily e-mail incrementals. Is there enough time off-hours to backup all of the data?
One way or another, it doesn't really matter *what* you do. If you don't back up to tape, cd, ftp, scratch monkey, reams of paper to be rescanned later, or whatever - if if you don't backup, you're fscked. To be perfectly honest, it's like mirroring - optimally, the backup copy is in a safe location offsite that only certain people can get to, and even more optimally is that if it's something that can be dismounted from a network and put in something like a safe deposit box at your bank or something. (They're less convenient than an FTP mirror or a disaster recovery shop, but much cheaper and perfect for those who has the initiative to run to the deposit box once per week with the 'granddaddy' backup.)
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Use disks. See : Mike Rubel's rsync backup system. You can't beat IDE disks on price/gb - Tapes are MORE expensive; They're fast, available on-line, and you'll probably be able to mount them on any machine in the next 10 years (which is not true for many tape drives).
I worked in the backup software industry for 10 years.
There were a couple of vendors that began to address this.
They were bought out by others, and quietly EOL-ed, or market-segmented into uselessness.
The problem is - there's really a bunch of loosely-connected problems that are solved by Tape backup. Or backup, in general. There's backup, disaster recovery, Storage mitigation, like HSM, replication, versioning, open-files, database backup (synchronization of relational files) etc. And differences in OS architecture, and even LAN implimentation make huge differences in how one approaches this problem. (ie. how do you restore an Application? Just it's executable? Libraries? What about shared libraries? How do you talk to the registry? etc. Got a can-opener? How do you restore the OS? is the target system set up and partitioned the same as the system you backed up?) Another problem is the utter stupidity of current file-systems. None of them were really designed with backup in mind, with regard to how metadata is stored.
My opinion, is that, Backup will continue to always be an ugly add-on hack that will never make everybody happy, until it's designed into the OS. Or at the very least, the file-system.
And the way backup software vendors have been dealing with things (ie. it's an opportunity to corner markets and make money off of people desperate to protect their businesses) - I simply don't see ANY vendor today, that's even remotely equipped to rise to the challenge of providing a well-engineered solution. Maybe Microsoft - but despite what Gartner says about them, they just plain don't have the "Vision".
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It's a little unclear if you are looking at an outsourced backup service (i.e. backing up to a service company over the network) or a disk based backup system.
I will make the assumption that you are looking at a disk based system. There are a number of factors you need to look at:
1, Capacity required. That is, how much space will you need now and in the future? Tape systems offer advantages in being (generally) able to handle large amounts of data, particularly if it's compressable.
2, Restore time. This is very important. How quickly do you need to get data back? A disk based system will obviously have advantages in that it will give you near instantaneous restores. Tape can also provide fast restores, if you get sufficiently expensive drives (e.g. AIT-3, 9840b/c).
3, Retention period. This is related to capacity requirements, particularly in disk based systems. How far back do you want to go? Tape offers the ability to easily store media offsite and import it back in.
4, Budget. Notice that I put this last. The other considerations IMHO are more important than price, particularly if you really value your data. Spend the money and get a quality system, regardless of whether you get disk or tape.
Without knowing a lot about your situation, here are some options to think about:
- If restore time is key, look at getting a NAS (Network Attached Storage) or ATA array and use rsync or standard utility (e.g. tar, dump etc) to backup to the array. You can then use a commercial product like NetBackup or Networker or an open source utility like AMANDA to archive the data to tape if you want more control over versioning and need some offsite DR.
- If capacity is your goal, tape is the most cost effective option. In spite of appearances, high capacity tapes like the 9840B, AIT-3 and LTO2 will often give lower overall cost per megabyte than disk. You will often also get more scalability, as the libraries are easily expandable in terms of slots and/or drives. You can multiplex backup/restores over several drives to get you the pwerformance you're after.
- Use snapshots. NetAPP and other NAS vendors offer this and they backup only what changes. They also give you very quick recovery times.
I favour a hybrid disk and tape approach. That is, backup to a cheap disk array using the method of your choice and then backup the array to tape (full backup on weekends, incrementals on weekdays). Use a four week cycle for your tapes, with a monthly offiste rotation. If you have a bit of budget, then HSM software like SAM-FS or Veritas Storage Migrator make the job even easier. They are basically filesystems that use a disk cache and backup/restore to/from tape in the background. You can then NFS/SAMBA mount the filesystem on any machine. You can also write multiple copies of the same files, which is handy.