Re: Backup on DDS-4 tapes
--pP0ycGQONqsnqIMP Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Monday, 14 March 2005 at 10:38:02 +0100, Ludo Koren wrote: Hi, I am using 5.2.1-RELEASE-p3 for backup on DDS-4 tapes 40GB in size. ... Why I cannot dump the filesystem on 2 tapes (it takes 3, it seems it works without compression) no matter if I use dump or cpio? What I am doing wrong? You're using dump :-) Dump is too stupid to understand compression or EOF marks, so it errs on the side of caution. It's also IMO not a very good backup medium unless you really want the incremental dump facility. Even between different releases of FreeBSD there are compatibility problems, and you can assume that there is no compatibility at all between different operating systems. You may find tar a better choice. Surprisingly http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/backup-basics.html in 16.1.7 suggests dump, though as the reference is used (maybe) outdated E. Zwicky link... Anyway, cpio cannot handle the problem too, and the tar in 5.2.1-RELEASE-p3 can handle multi-volume backup, but in the 5.3-STABLE don't according to the man page. I wonder what is then the best solution. Regards, lk ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Backup on DDS-4 tapes
# /sbin/dump -Lu0 -B 41943040 -C 32 -f /dev/sa0 /usr I would guess that your tape drive does hardware compression in which case the amount of data which fits on a tape is variable. In such a case you can't tell dump how big the tape is -- I haven't used options like -B since 1600bpi reel-to-reel tapes, except in my day you specified how many feet of tape you had :-) from man dump -a ``auto-size''. Bypass all tape length considerations, and enforce writing until an end-of-media indication is returned. This fits best for most modern tape drives. Use of this option is particularly recommended when appending to an existing tape, or using a tape drive with hardware compression (where you can never be sure about the compression ratio). It doesn't help either... The result is the same. Don't know -L, must be a 5.x thing. Try: -L This option is to notify dump that it is dumping a live file sys- tem. To obtain a consistent dump image, dump takes a snapshot of the file system in the .snap directory in the root of the filesystem being dumped and then does a dump of the snapshot. The snapshot is removed when the dump is complete. If the .snap directory does not exist in the root of the filesystem being dumped, the dump will fail. This problem can be corrected by creating a .snap directory in the root of the filesystem to be dumped; its owner should be root, its group should be operator, and its mode should be 0770. /sbin/dump -Lu0 -a -C 32 -f /dev/sa0 /usr I use -b 64 as well. Use cpio/tar at your peril as they may not do devices right and may not understand filesystem flags. --Alex lk ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
RE: Backup on DDS-4 tapes
-Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Ludo Koren Sent: Wednesday, March 16, 2005 1:19 AM To: [EMAIL PROTECTED] Cc: freebsd-questions@freebsd.org Subject: Re: Backup on DDS-4 tapes Anyway, cpio cannot handle the problem too, and the tar in 5.2.1-RELEASE-p3 can handle multi-volume backup, but in the 5.3-STABLE don't according to the man page. I have never found multivolume tar archives to work unless I defined the size of each tape. Waiting for the tape device to return an EOT to the tar program always ended up with junk. If the tar in 5.3 doesen't have this option any longer why don't you compile a tar that does? Anyway, I think your problem is your tape device has it's dip switch set to disable compression. In that position it takes a SCSI command to turn compression on. If you flip the switch then the tape device starts with compression on, and it takes a scsi command to turn it off. This is hardware compression I am referring to, of course. Ted ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Backup on DDS-4 tapes
Ludo Koren wrote: It doesn't help either... The result is the same. Just to check I'm understanding your problem correctly -- you're expecting to write much more data to the tape than is actually being written. If that's correct, then there's a couple things I can think of: 1) Your tape drive isn't doing hardware compression. Check the manual and see if there are any dip switches you need to set. (Make a note of how they're set before you change anything, so you can go back to what you had originally!). When you say the result is the same, if it used exactly the same number of tapes (down to the decimal point) then that definitely suggests that your tape drive is not compressing. 2) The data you're writing to the tape is already mostly compressed, so you won't fit as much as you might if it were uncompressed data. Also, the 40Gb per tape that you quote is, I think, the MAXIMUM amount of data the tape will take. It's only 20Gb native. 40Gb is how much will fit at optimum compression, which you never get. It's unlikely to be a FreeBSD problem because I regularly fit 6-7Gb on a DDS-2, which has a native size of 4Gb. I use dump options like the ones in my last message. --Alex ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Backup on DDS-4 tapes
Ludo Koren wrote: It doesn't help either... The result is the same. Just to check I'm understanding your problem correctly -- you're expecting to write much more data to the tape than is actually being written. That's right. I suppose that 54GB of data could fit on 2 40GB tapes... If that's correct, then there's a couple things I can think of: 1) Your tape drive isn't doing hardware compression. Check the manual and see if there are any dip switches you need to set. (Make a note of how they're set before you change anything, so you can go back to what you had originally!). I'll check this When you say the result is the same, if it used exactly the same number of tapes (down to the decimal point) then that definitely suggests that your tape drive is not compressing. 2) The data you're writing to the tape is already mostly compressed, so you won't fit as much as you might if it were uncompressed data. I will do statistics about files. Also, the 40Gb per tape that you quote is, I think, the MAXIMUM amount of data the tape will take. It's only 20Gb native. 40Gb is how much will fit at optimum compression, which you never get. It's unlikely to be a FreeBSD problem because I regularly fit 6-7Gb on a DDS-2, which has a native size of 4Gb. I use dump options like the ones in my last message. --Alex Thank, for your suggestions. lk ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Backup on DDS-4 tapes
Ludo Koren wrote: # /sbin/dump -Lu0 -B 41943040 -C 32 -f /dev/sa0 /usr I would guess that your tape drive does hardware compression in which case the amount of data which fits on a tape is variable. In such a case you can't tell dump how big the tape is -- I haven't used options like -B since 1600bpi reel-to-reel tapes, except in my day you specified how many feet of tape you had :-) from man dump -a ``auto-size''. Bypass all tape length considerations, and enforce writing until an end-of-media indication is returned. This fits best for most modern tape drives. Use of this option is particularly recommended when appending to an existing tape, or using a tape drive with hardware compression (where you can never be sure about the compression ratio). Don't know -L, must be a 5.x thing. Try: /sbin/dump -Lu0 -a -C 32 -f /dev/sa0 /usr I use -b 64 as well. Use cpio/tar at your peril as they may not do devices right and may not understand filesystem flags. --Alex ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Backup on DDS-4 tapes
Hi, I am using 5.2.1-RELEASE-p3 for backup on DDS-4 tapes 40GB in size. # df -k Filesystem 1K-blocks UsedAvail Capacity Mounted on /dev/vinum/root 1016162 157405 77746517%/ devfs 110 100%/dev /dev/vinum/usr 84746248 54467390 2349916070%/usr procfs 440 100%/proc # camcontrol devlist -v scbus0 on ahd0 bus 0: IBM IC35L018UWD210-0 S5BSat scbus0 target 3 lun 0 (pass0,da0) IBM IC35L073UWDY10-0 S25Fat scbus0 target 9 lun 0 (pass1,da1) HP C5683A C005 at scbus0 target 10 lun 0 (sa0,pass2) at scbus0 target -1 lun -1 () scbus1 on ahd1 bus 0: IBM IC35L018UWD210-0 S5BSat scbus1 target 1 lun 0 (pass3,da2) IBM IC35L073UWDY10-0 S23Cat scbus1 target 8 lun 0 (pass4,da3) at scbus1 target -1 lun -1 () scbus-1 on xpt0 bus 0: at scbus-1 target -1 lun -1 (xpt0) # /sbin/dump -SLu0 -B 41943040 -C 32 -f /dev/sa0 /usr DUMP: Date of this level 0 dump: Mon Mar 14 10:29:51 2005 DUMP: Date of last level 0 dump: the epoch DUMP: Dumping snapshot of /dev/vinum/usr (/usr) to /dev/sa0 DUMP: mapping (Pass I) [regular files] DUMP: Cache 32 MB, blocksize = 65536 DUMP: mapping (Pass II) [directories] DUMP: estimated 54189311 tape blocks on 1.29 tape(s). # # mt -f /dev/sa0 status Mode Density Blocksize bpi Compression Current: 0x26:DDS-4 variable 97000DCLZ -available modes- 0:0x26:DDS-4 variable 97000DCLZ 1:0x26:DDS-4 variable 97000DCLZ 2:0x26:DDS-4 variable 97000DCLZ 3:0x26:DDS-4 variable 97000DCLZ - Current Driver State: at rest. - File Number: 0 Record Number: 0 Residual Count 0 I am using the following command: # /sbin/dump -Lu0 -B 41943040 -C 32 -f /dev/sa0 /usr or # /sbin/dump -aLu0 -C 32 -f /dev/sa0 /usr Why I cannot dump the filesystem on 2 tapes (it takes 3, it seems it works without compression) no matter if I use dump or cpio? What I am doing wrong? Any hints appreciated. Thank you very much in advance. Regards, lk ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Backup on DDS-4 tapes
On Monday, 14 March 2005 at 10:38:02 +0100, Ludo Koren wrote: Hi, I am using 5.2.1-RELEASE-p3 for backup on DDS-4 tapes 40GB in size. ... Why I cannot dump the filesystem on 2 tapes (it takes 3, it seems it works without compression) no matter if I use dump or cpio? What I am doing wrong? You're using dump :-) Dump is too stupid to understand compression or EOF marks, so it errs on the side of caution. It's also IMO not a very good backup medium unless you really want the incremental dump facility. Even between different releases of FreeBSD there are compatibility problems, and you can assume that there is no compatibility at all between different operating systems. You may find tar a better choice. Greg -- When replying to this message, please copy the original recipients. If you don't, I may ignore the reply or reply to the original recipients. For more information, see http://www.lemis.com/questions.html See complete headers for address and phone numbers. pgpdih4q62i0S.pgp Description: PGP signature
