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Backup Strategies
- Thread starter raptoid
- Start date
This is a white paper comparing SDLT and LTO.
Unfortunately, I had just finished typing a response to both posts above, but my browser erased it with some unknown keystroke.
Let me try to recall and summarize my original post (which is now gone)...
I've used DLT and AIT for several years. DLT was good technology for its time, but like the Edsel, newer, better things have come along. AIT is good and by 2008 Sony supposedly will have AIT-6 running at 96MB/sec and fitting 800GB per tape.
LTO is new. I've used it for about 1-year. In 2003, LTO will release LTO-2 running 400GB per tape and 20-40MB/sec. These numbers for AIT and LTO are based on 2:1 compression. I have seen AIT-2 compress over 3:1, but that is probably more a reflection of my data.
LTO has a roadmap out to 2007, and by then they claim to have LTO running at 800GB storage and 80-160MB/sec.
Media costs for LTO are around $100 per tape, SDLT us over $100, and DLT is around $60. AIT-2 is around $60.
LTO is rated at a 100% duly cycle, meaning you can run it all the time. I don't recall duty cycles on AIT, DLT or SDLT.
I've got a Qualstar LTO library, an IBM LTO standalone drive, and 3 DLT's (1 DLT 7000 and 2 DLT 4000).
Be careful of marketing hype. In the paper I mentioned at the beginning of my post, the reviewers state that the SDLT is substantially faster in some operations, the LTO is marginally faster in some operations, and some operations there is no clear winner. I ran the numbers myself, and in either case, the margin of speed is [red]13%[/red]. I asked Quantum/ATL to clear this up. I don't expect to hear anything.
If you want more, just ask.
Bill.
Now on to backup strategies.
Oracle supports "hot backups". I don't know if SQL Server does.
You have 2 options with Oracle : Hot or Cold backups.
A cold backup involves unmounting the database (take Oracle down) and perform a backup of all Oracle data. Obviously, the database is unusable at this time. It might be a good idea to backup the operating system at this time also.
A hot backup involves backing up the database with it still running. Oracle sets a flag internally stating that a backup is running, and performs the backup. There is impact on the system resources as this occurs, and also an impact on database response time. Things WILL slow down.
In some cases, you might have a 3rd option - backup to disk. In this case, you perform a backup to disk images, and then offload those disk images to tape. This is the method that we use on one of our systems.
If SQL Server doesn't support hot backups, your only option will be a cold backup.
If you need more, write back.
Bill.
Oracle supports "hot backups". I don't know if SQL Server does.
You have 2 options with Oracle : Hot or Cold backups.
A cold backup involves unmounting the database (take Oracle down) and perform a backup of all Oracle data. Obviously, the database is unusable at this time. It might be a good idea to backup the operating system at this time also.
A hot backup involves backing up the database with it still running. Oracle sets a flag internally stating that a backup is running, and performs the backup. There is impact on the system resources as this occurs, and also an impact on database response time. Things WILL slow down.
In some cases, you might have a 3rd option - backup to disk. In this case, you perform a backup to disk images, and then offload those disk images to tape. This is the method that we use on one of our systems.
If SQL Server doesn't support hot backups, your only option will be a cold backup.
If you need more, write back.
Bill.
- Thread starter
- #5
Tape cycles are determined by business rules. In our case, we run a 30-day cycle. We run 2 copies per backup, and 1 copy is sent offsite. In either case, the tapes are not re-used for a period of 30-days. Quarter-end tapes are saved a bit longer, and year-end tapes are saved a year.
Bill.
Bill.
Thanks for the info, now onto a follow-up question.
What is your experience with support from the various vendors? We currently use Overland DLT8000's in a jukebox and have had nothing but trouble with them and the support is less than stellar. We'd like to try other vendors, but need a starting point.
What is your experience with support from the various vendors? We currently use Overland DLT8000's in a jukebox and have had nothing but trouble with them and the support is less than stellar. We'd like to try other vendors, but need a starting point.
I've used IBM DLT libraries and Qualstar AIT / LTO libraries.
The first version of the IBM DLT library was a joke. The later firmware upgrades fixed alot of bugs and it is pretty good now. The Qualstar AIT and LTO libraries are good. ADIC also makes good libraries. I've used Cybernetics standalones in the past and they're good as well. I [somewhat] support a Quantum DLT library here now, and I don't have any problems with it.
Good luck!
Bill.
The first version of the IBM DLT library was a joke. The later firmware upgrades fixed alot of bugs and it is pretty good now. The Qualstar AIT and LTO libraries are good. ADIC also makes good libraries. I've used Cybernetics standalones in the past and they're good as well. I [somewhat] support a Quantum DLT library here now, and I don't have any problems with it.
Good luck!
Bill.
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