Thanks to Kevin, Brian, Sam, Matthew. There will be very few servers on a private switched network and the application will have to be shut down once per week for the big backup, the network will be quiet so no contention. SDLT appears to be faster than 100BT! There is a new version of the SDLT which is even faster. I guess to beat it will require gigabit Ethernet. Thanks for your help. Richard ============ 11 MBytes/sec = 88Mbits/sec < 100Mbits/sec or 100Mbits/sec = 12.5MBytes/sec > 11MBytes/sec The network would be quicker, however I know the network has additional overhead, so you will not see 12.5MB/s, and I would assume the tape would also have some overhead. If "less efficient" means more overhead, I would say the network. If "less efficient" means slower, I would think the tape. If you are copying the data to the box with the tape drive than this is a moot point since all backup will be local. Brian ========== test your network speed. I didn't get near 90% bandwidth throughput speeds when I was moving 30G. faster than rcp was ufsdump | ufsrestore... but that only worked close to line speed if I was running 8 or more simultaneously. One process ran at much slower than line speed. YMMV. good luck. Kevin =========== > Sun on their website claim 11 Mbytes (not bits) per second for Super > DLT. The third-party external SDLT connected to one of my E250s gives me about 6Mbytes/sec average for the biggest (55Gb or so) partition it backs up. > 11 MB per second appears to me to be faster than I could expect network > copies to run at. Our network is 100BaseT Full Duplex. I would copy > the data using whatever is fastest be it ftp, scp, rcp or NFS. The `dd' that this (local) partition is backed up with, under the hood, does that 55Gb in about 160 minutes. That's about 50Mbits/sec average, I reckon. > If I copied say 40GB to SDLT tape or over the network should I expect > about 1 hour in either case? I reckon it depends mostly on what else any network components in the path might be doing at the time. When I look at my network logs while a backup is in progress, I can spot other activity on, say a LAN switch that has a backup client and server talking to each other as a dip in the traffic between that client and server. If you can guarantee to be able to saturate client and server interfaces and don't have to put up with servicing other traffic with the network components involved, you may well win with over-the-net copying, but the one thing a local SDLT will give you is repeatability, even if it is somewhat slower. Sam My email addresses are: "Richard_Mackerras" in the domain "MySun.Com" "Richard.Mackerras" in the domain "AvonAndSomerset.Police.UK" ----- Original Message ----- From: "Richard Mackerras" <richard_mackerras@mysun.com> Date: Thursday, October 31, 2002 2:16 pm Subject: Which is faster: SDLT or 100BT Ethernet Full Duplex? > Hi, > > Sun on their website claim 11 Mbytes (not bits) per second for > Super > DLT. > > 11 MB per second appears to me to be faster than I could expect > network > copies to run at. Our network is 100BaseT Full Duplex. I would > copy the > data using whatever is fastest be it ftp, scp, rcp or NFS. > > If I copied say 40GB to SDLT tape or over the network should I > expect > about 1 hour in either case? > > Which is going to be less efficient, Ethernet? > > TIA, > > Richard > > > My email addresses are: > "Richard_Mackerras" in the domain "MySun.Com" > "Richard.Mackerras" in the domain "AvonAndSomerset.Police.UK" > _______________________________________________ > sunmanagers mailing list > sunmanagers@sunmanagers.org > http://www.sunmanagers.org/mailman/listinfo/sunmanagers > My email addresses are: "Richard_Mackerras" in the domain "MySun.Com" "Richard.Mackerras" in the domain "AvonAndSomerset.Police.UK" ----- Original Message ----- From: "Richard Mackerras" <richard_mackerras@mysun.com> Date: Thursday, October 31, 2002 2:16 pm Subject: Which is faster: SDLT or 100BT Ethernet Full Duplex? > Hi, > > Sun on their website claim 11 Mbites (not bits) per second for > Super > DLT. > > 11 MB per second appears to me to be faster than I could expect > network > copies to run at. Our network is 100BaseT Full Duplex. I would > copy the > data using whatever is fastest be it ftp, scp, rcp or NFS. > > If I copied say 40GB to SDLT tape or over the network should I > expect > about 1 hour in either case? > > Which is going to be less efficient, Ethernet? > > TIA, > > Richard > > > My email addresses are: > "Richard_Mackerras" in the domain "MySun.Com" > "Richard.Mackerras" in the domain "AvonAndSomerset.Police.UK" > _______________________________________________ > sunmanagers mailing list > sunmanagers@sunmanagers.org > http://www.sunmanagers.org/mailman/listinfo/sunmanagers _______________________________________________ sunmanagers mailing list sunmanagers@sunmanagers.org http://www.sunmanagers.org/mailman/listinfo/sunmanagersReceived on Thu Oct 31 10:52:46 2002
This archive was generated by hypermail 2.1.8 : Thu Mar 03 2016 - 06:42:57 EST