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Author Topic: Tape backup for MacOS X 10.4 ?  (Read 8521 times)
francois
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« Reply #40 on: October 03, 2005, 09:30:21 AM »
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Can you provide any hard evidence for this ? I'm using external FW400 & FW800 drives on a Mac G5, and I can't say I notice them being particularly slow...
Same here!

Francois
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Francois
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« Reply #41 on: October 03, 2005, 10:11:34 AM »
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My FW800 and 400 drives are extremely fast, I regularly have 88MB/s transfer
rates from the 800 drive - I donīt consider that as very slow.
I wouldn't either but I have a hard time buying that number. The FW800 spec allows for a max transfer speed of 80MB/s but since Apple underrated FW400, I'll believe it's possible for it to reach 88MB/s (though 8MB/s overrating is a bit of a stretch).

However, I have never seen any PATA drive exceed a 60MB/s transfer speed or any SATA drive exceed 70MB/s.

Perhaps your test was read/write and not transfer.
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Concorde-SST
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« Reply #42 on: October 03, 2005, 10:21:48 AM »
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Daniel,

it was, believe it or not, sustained transfer. But I donīt know how
the program is calculating the speeds, since there is a difference
between 1 MB, being 1000 KB or 1024 KB (which is correct).

Iīve got 6 GB of RAM, dual 2 GHz G5 and plenty of HDD space -
so I guess this speed should be expected (of course only one
FW800 drive is live).

best,

Andreas.
 :blues:
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Lust4Life
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« Reply #43 on: October 03, 2005, 10:29:17 AM »
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I was told this last week by a buddy that builds Macs.  Quized him this morning and here is what I got back:

I couldn't find all the articles I read last week, but in the following, I did read it wrong.  This is referring to a FW800 add in PCI X card for running a multiple drive array.  
 
Have to do some more checking to see if it's the same on the Mac's internal FW 800.  
  
 http://www.barefeats.com/hard35.html
Last November we discovered a problem with multi-channel FireWire 800 RAID on the G5. The sustained WRITE speed was much lower than SATA... AND... much lower than a Dual G4/1.42 Power Mac with the same configuration (see second graph above).

I've asked around as to why the G5 could only achieve sustained WRITE speeds half that of the G4. Nobody has any hard answers. Only theories. Some blame Apple's PCI-X controllers. Some think it's a G5 firmware bug. Some think it's a deficiency in the PCI controllers or an incompatibility between those controllers and the G5's PCI-X slots.
Two of my colleagues in two other labs with similar setups observed the same phenomenon. We tried different drives, different case kits, and different PCI controllers -- same result. We even tried putting one FW800 card in slot 4 (133Mhz) and one card in slot 3 or 2 (100MHz - different bus) -- same result.

I'm hoping Apple engineers can help solve this mystery since I've passed my findings on to them. I hope it's a simple firmware fix or OS patch -- and doesn't require a Rev B motherboard!

Just offered for your info - don't want to start a range war over this.
Jack
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yoni
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« Reply #44 on: October 03, 2005, 10:29:55 AM »
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Quick comments regarding my experiences over many years of running a medium sized medical imaging lab with large amount of data production. Tape (LTO) is economical on large scale but must be cycled to maintain reliability. We interlace four tape sets biweekly with two set kept off-site. Every 18 month, we replace the tapes. Tape is reasonable when dealing with many GB of incremental daily network backup. LTO drives such as Exabyte are expensive as are the tapes. Cheaper tape solution, eg DAT, are unreliable. Used to use DATs and have had some serious meltdowns due to retrieval failures.

For smaller operation, tape is not a good solution. For home (largely my photography studio efforts) I have used CD and DVD-a lousy solution, but am just now switching to 400GB firewire/USB drive with retrospect regulated backup. Again, multiple systems (2), cycling (monthly), one system kept off-site.

I would recommend backup software not file copy-retrospect works. You want to be able to rebuild your entire system relatively effortlessly.
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Concorde-SST
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« Reply #45 on: October 03, 2005, 10:41:05 AM »
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Yoni,

I agree with your opinion - depending on how much storage you "waste" in
a given amount of time tape may be the best solution. In cases such as I
see mine, I now found out that HDD RAID would be the best solution.

Of course parallel to this Iīd use DVD backup, re-do this every 12-14 months.
One copy would be here in my home, the other in a safe room about 130 miles
away.

I donīt need retrospect - just the photoshop work files (heavy layered) and the
RIP print files are backupped. System and programs are readily available on
DVDīs.

I call this my own minimal invasive routine :-)

best,

Andreas.

:blues: :blues: :blues:
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