You can try using tar with the I flag - that will use bzip2 compression.
However, if you value your data - NEVER use compression on a backup - should part (ie one bit) of the backup be corrupted (common with tapes) the whole archive is useless. Matt At Wednesday, 10-04-02 12:13 (+1000), Gonzalo Servat wrote: >Yes, Arkeia claims it's using 1.2 compression (with LZ1 I think). What >sort of compression could I use with tar to achieve similar results to >Arkeia? I tried compress & gzip and it went just as slow > >What's the switch to play with the blocking factor? > >Also, I tried setting the block size to 2048 to see if it speeds it up >and it didn't help at all.. > >It's an Ecrix VXA-1 Tape Drive on a Adaptec 2940 SCSI Card. > From dmesg: > >scsi0 : Adaptec AIC7XXX EISA/VLB/PCI SCSI HBA DRIVER, Rev 6.2.4 > <Adaptec 2940 SCSI adapter> > aic7870: Single Channel A, SCSI Id=7, 16/253 SCBs > > Vendor: ECRIX Model: VXA-1 Rev: 2848 > Type: Sequential-Access ANSI SCSI revision: 02 >(scsi0:A:4): 10.000MB/s transfers (10.000MHz, offset 15) >st: Version 20011103, bufsize 32768, wrt 30720, max init. bufs 4, s/g >segs 16 >Attached scsi tape st0 at scsi0, channel 0, id 4, lun 0 > >Arkeia *is* doing a full backup. > >I'll give ctar a go. Maybe tar can't compress as well as Arkeia can? > >Thanks again Matt. > > >On Wed, 2002-04-10 at 10:47, Matt Hyne wrote: > > > > If Arkeia is backing up at 180Mb/min then this is equivalent to 3Mb/s, > 2-3x > > faster than tar. > > > > Is Arkeia using compression ??? It is possible, and that may be why it is > > reporting faster transfer times to tape than tar is. > > > > You can also play with the tar blocking factor - it will depend on the > > network transfer speed. > > > > The other thing is, what sort of tape drive are you using, what sort of > > controller ? What is the maximum rated transfer rate for the tape drive ? > > > > Another stupid question - is Arkeia doing a FULL backup or an incremental ? > > > > From the look of this, you network is probably not the bottleneck. I > > would also suggest you take a look at ctar (do a google search). It costs > > money but you can install a trial version and compare that. > > > > Matt > > > > At Wednesday, 10-04-02 09:43 (+1000), Gonzalo Servat wrote: > > >Hi Matt > > > > > >I took your advice and tried backing up / on the backup server > > >(excluding /dev and /proc of course) to tape and tar reported: > > > > > >Total bytes written: 1427005440 (1.3GB, 1.2MB/s) > > > > > >It took about 15 minutes to complete this. My fileserver has about 30GB > > >worth of data. So, it would take approximately 6 hours to complete using > > >tar. This is just for the fileserver. It's actually taking a lot longer > > >than 6 hours (since it has to come over through the network) but > > >anyway... using Arkeia, I can backup the fileserver AND mail server > > >(which is only an extra 3 or so gigs) in 2 hours and 20 minutes. Arkeia > > >reports the speed was 180MB/min. > > > > > >There's something I'm doing wrong here and Arkeia is doing right because > > >I don't understand how Arkeia can backup ~160 faster than tar. > > > > > >Any further ideas?? > > > > > > > > > > > >On Tue, 2002-04-09 at 17:56, Matt Hyne wrote: > > > > > > > > Generally, tapes are streaming, so it is possible that if the transfer > > > rate > > > > across the network is slow then more tape may be required for the same > > > > amount of data. > > > > > > > > Really - you need to determine the bottleneck - can you tar from one > > > > machine to the HDD on another and see how long it takes - and then > locally > > > > tar this data to the tape drive. That should give you some good > ideas of > > > > where the performance bottleneck is. > > > > > > > > At Tuesday, 09-04-02 16:42 (+1000), Gonzalo Servat wrote: > > > > >Hi All > > > > > > > > > >I was performing backups across the network using Arkeia until one day > > > > >the wrong tape was inserted and the whole tape cycle went haywire > (as it > > > > >requires you enter the right tape with the right label or you get > a nice > > > > >email in the morning asking you to insert the right tape - when > infact, > > > > >I DID enter the right tape) and so I got pretty p@#@ed off at > Arkeia and > > > > >decided to switch to using tar (as I can insert any tape and it will > > > > >write, plus tar is pretty universal accross *nix systems so I can > > > > >restore on any system) > > > > > > > > > >Aaaanyway, the point of my story is... it would normally take > ~2.5hours > > > > >to backup 33GB across the network using Arkeia to tape. > > > > >With tar, it takes over 8 hours at which point it gives me a nice "no > > > > >space left on device" message on the screen. > > > > > > > > > >I'm not using gzip compression. I've tried this and it doesn't > help the > > > > >speed problem (or capacity problem) > > > > > > > > > >The backup unit is an Ecrix VXA-1 using V17 tapes. > > > > > > > > > >Any ideas?? > > > > > > > > > >Thanks in advance! > > > > > > > > > >Regards, > > > > > > > > > >Gonzalo. > > > > > > > > > > > > > > >-- > > > > >SLUG - Sydney Linux User Group Mailing List - http://slug.org.au/ > > > > >More Info: http://lists.slug.org.au/listinfo/slug > > > > > > > > > > > > -- > > > > SLUG - Sydney Linux User Group Mailing List - http://slug.org.au/ > > > > More Info: http://lists.slug.org.au/listinfo/slug > > > > > > -- > > SLUG - Sydney Linux User Group Mailing List - http://slug.org.au/ > > More Info: http://lists.slug.org.au/listinfo/slug -- SLUG - Sydney Linux User Group Mailing List - http://slug.org.au/ More Info: http://lists.slug.org.au/listinfo/slug
