Leitner, Timothy wrote:
All,
How many places have implemented tapeless backup environments? I
don't mean virtual tape that has tape on the back-end but no tape at
all. We are exploring different options and the wintel side of the house
is heading down the totally tapeless path. That makes me nervous but I'm
getting old.
Well, BTDT (Been There, Done That).
Some time ago I decide to use DASD instead of tape for backups. The
reason was ...budget constraint. Yes, disk backup was cheaper.
I repeated it for "open" systems as well.
However YMMV, Strongly. The major factor is amount of data. Another
important factor is data retention requirements. How many copies, how
long kept, etc. In fact we distinguish two things: backup, and archive.
Things to consider:
- Amount of data. The more data, the cheaper tape is.
- Activity. The more archival copies, the better for tape.
- SOFTWARE! Your backup software may or may not support DASD in every
operation. AFAIK DFSMShsm does not support DASD for volume dumps.
- DASD boxes. If you decide to use second hand equipment (IMHO it's ok
for backup), then the price analyzis changes significantly. From the
other hand I don't like second hand tape drives (BTDT) because of wear,
MTBF, etc.
- DR scenarios. Some datacenters still use PTAM method. Tapes offsite.
Well - in this case you have to have tapes. For remote copy solutions
(PPRC, H(A)RC, SRDF) it's easier to replicate backups and migrated data.
In tape world you can buy remote copy solution for virtual tapes (both
STK/Sun and IBM do offer such solutions). You can also have two ATLs
without virtual tapes (much cheaper) and use software for data replication.
- Offline media. DASD backups could be erased by accident (human error).
It is oftenly mentioned. Of course tapes can be overwritten as well, but
the tapes can be locked up (physically) - disks cannot. However in ATL
there is no manual control what tapes is being mounted, so human error
is as possible as in DASD.
BTW: several years ago it was discussed whether to use MO
(Magneto-Optical) media for backups. Although this is the most reliable
media ever known, the technology is rather fading due to capacity,
price, performance reasons. MO are small, slow and expensive.
So, nowadays we discuss tape or disk. No other option apply.
My $0.02
Regards
--
Radoslaw Skorupka
Lodz, Poland
--
BRE Bank SA
ul. Senatorska 18
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www.brebank.pl
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Wedug stanu na dzie 01.01.2008 r. kapita zakadowy BRE Banku SA wynosi
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