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We have recently purchased a Exabyte Magnum LTO3 autoloader and Retrospect server 6.1 to allow for nightly backups of the various RAIDS we use for video and post production storage. This is running on a G5 1.8ghz 10.4.7 with an ATTO UltraSCSI160 PCI card.


If we connect a Firewire drive or even a RAID 5 array to the G5 server we regularly see speeds of up to 1400MB per minute in Retrospect (which is enough to keep me from complaining but still not near the theoretical 4800MB per minute that 80MB x 60 seconds gives) but when we try to backup over the network we don't get much more than 360MB per minute (according to the Retrospect log) which means the night isn't long enough to backup the 1-2 terabytes I need to do. Retrospect software compression is off. The tape drive has compression on I presume but should still be good for 80MB per second according to the documentation.


We are running all gigabit ethernet and switches throughout and since the backup is at night I know there is no other traffic on the network. I know that I can usually expect about 65MB per second out of gigabit ethernet.


Can anyone tell me what speed I can reasonably expect? Is 400MB per minute really it? Is there something I can do to speed things up?

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Only the xServe supports jumbo frames (from what I have read) and our switches don't. We only have one xServe and the rest are G4, G5s. Based on my reading it seems recommended to have all devices using jumbo frames or none at all as it can cause problems for the switches. So this wouldn't seem to be an option. Just out of curiosity what speed difference can you expect out of jumb frames?


So using non-jumbo frame gig-ethernet what performance should I be seeing out of retrospect and LTO3?

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My LTO2 drive can easily average 1500 MB/Min copying from a client computer. I have seen as much as 4000 MB/Minute copying from my AX150 to tape via Backup Set Transfer.


I am using the LTO2 on Windows.


Run a test backup to a File Backup Set. If the speed is still at 250 MB/Min then you know the drive isn't the problem. If the speed is much higher writing to a HD, then you have SCSI issues.

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I don't have LTO . I am running "duplicate" script and I am getting 1100MB/min on GB switch to external FW HD. On My VXA-3 single tape drive (scsi) on older g4/866 mac I am getting 700MB/min.


All Macs running Tiger 10.4.7 or 10.4.8 and Retro 6.1.126.


1100MB/min is a bit over 18 MB/sec. It's not bad. I don't thing you will ever get over 30 MB/sec. (1800MB/min)


Helios utility show that speed (write/read over GB from my server (OS X Server 10.3.9, G5-dual 2Ghz tower) is about 40MB/sec. or 2400MB/min



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Thanks for the replies guys.


The SCSI Card is an ATTO UL4S so its SCSI320 and not 160 as I mentioned before.


Not convinced that the slowdown is caused by either the ATTO card or the G5. With local drives mounted (either on SCSI, Firewire 400 Firewire 800 or on the FibreChannel RAIDs) we were getting between 1100MB per minute and 1600MB per minute. As soon as you try to back up anything over the network it slows to between 200mb per minute and 500mb per minute depending on network traffic.


I guess I will have to reconfigure all of my racks so that the Autoloader is connected to the same physical machine as the RAIDs. Bit of a nightmare though so much for the ease of network backups.

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