Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!att!dptg!ulysses!ucbvax!pro-grouch.cts.com!rmichel From: rmichel@pro-grouch.cts.com (Russel Michel) Newsgroups: comp.sys.apple Subject: Re: hard disk backup programs Message-ID: <10317.apple.net@pro-grouch> Date: 22 Feb 90 02:22:57 GMT Sender: usenet@ucbvax.BERKELEY.EDU Organization: The Internet Lines: 165 In-Reply-To: message from mattd@Apple.COM Since the topic of backup programs has come up several times lately, and people have mentioned the new kid on the block, Salvation, I thought I'd post a comparison of the two programs available that can handle all GSOS files (specifically meaning the capability of handling forked files). It was written by Glen Bredon of ProSel fame, so it's definately biased, as Glen freely admits. It does, however, have some good info for those who might be considering one of these two (ProSel-16 & Salvation). Here it is: Comparison of the ProSel-16 backup facility and Salvation. ---------------------------------------------------------- Since I am the author of ProSel-16, I am very biased, and you should keep that in mind. Because of that, I have attempted to limit things to factual items in this report. Also, I am not going to discuss the minor features of either program since that would be hard to do without biased value judgments. Of course, the question of what features are major or minor is also a value judgement, but there is no escaping that. The following benchmarks were done with my regular main directory which is slightly over 15MB in size. Timings were done with a stopwatch. In the case of ProSel-16 the watch was started as soon as the backup item was selected from the ProSel screen, the item being an automated backup spec so that the backup ran from that point with no further user access. In the case of Salvation, the watch was started when Salvation was selected and stopped whenever user input (mouse clicks) had to be done, until the backup began. Although Salvation allows use of macros, it is not fully automatic in the way ProSel-16 is, and it seems to eat up at least 12 seconds for mouse clicking to get things started, beyond the given times. All backups are full backups of the entire volume. Times are in minutes and seconds. Salvation (version 1.0): Backup with verify (1)...................................31:12.....20 disks Backup without verify....................................24:55.....20 disks Restore (5)..............................................? ProSel-16 (version 8.40): Backup, error correction, no verify, graphic, dir (1,2)..26:28.....19 disks Backup, no error corr., no verify, graphic, dir (4)......24:10.....17 disks Backup, no error corr., verify, graphic, dir.............32:43.....17 disks Backup, error correction, no verify, text, no dir (3)....25:05.....19 disks Backup, no error corr., no verify, text, no dir..........22:38.....17 disks Backup, no error corr., verify, text, no dir.............31:16.....17 disks Restore, error correction................................25:49 Notes: ------ (1) This is the mode I would recommend using with this program. (2) "dir" refers to the optional directory written during the backup. Salvation requires a separate directory disk; ProSel-16 keeps a directory on each disk, and the optional directory is for further convenience for the user (it could be put in a database, for example). (3) The main difference between text and graphics modes timings in ProSel-16 is due to the scrolling of display of files being backed up. Salvation does not use this type of display. Although the ProSel-16 text mode is slightly faster, I like the graphics option and scrolling enough to suffer an extra minute or two. (4) Error correction is the most important feature of the ProSel-16 backup and I strongly recommend its use. Since Salvation does not have this feature, the times for ProSel-16 without that option are listed. (But really, use the error correction, it can save your butt.) (5) I could not time Restore with Salvation because it gave me a Fatal error $48 while writing the files read from backup disk 4. This error is "volume full" but it was nowhere near full. A retry from the beginning produced the same problem. I have no idea why this happened and it could be a fluke. Also, I attempted to restore to a separate volume from the one backed up but it insisted on putting files in a folder instead of just replacing the existing files, so I had to restore to my main volume, which was the one backed up. Major features Salvation ProSel-16 -------------- --------- --------- File oriented Yes Yes Incremental mode Yes Yes Compound mode No Yes (6) Error correction No Yes (7) Compression No (8) Yes (8) Can use two drives No (9) Yes Can handle all system files No (10) Yes Can erase before restore No Yes Cost $50 + $5 P&H $60 (postpaid) More notes: ----------- (6) Compound incremental mode (sometimes called differential) is a way of doing incremental backups that requires only one set of backup disks instead of a set for each day until the next full backup. (7) Error correction obviates the need for verification, but it is much more than that. Disks often go bad long after they have been written and verified. Error correction is an advanced feature that will, with high probability of success, allow 100% correct restoration from damaged disks. (8) The compression in ProSel-16 is mainly for sparse files which, if expanded, could span up to 21 3.5" disks for a simple 5 block file. These files are rare but they do exist and some programs use them for data files. It is for that reason that earlier versions of the ProSel-16 backup had restrictions on sparse files, something that is no longer needed. Salvation fully expands sparse files, and thus has the same problem that the original version of the ProSel-16 backup had with them. (9) Salvation can use any drive, but you cannot put backup disks in two drives at the same time since the program will always insist on writing to the first one in the chain. The advantage of being able to write to two such drives, as ProSel-16 can, is that you can be away longer before having to replace the disks. (10) Not on the boot disk, but it could be done if you boot from a separate disk for the backup or restore. Remarks: -------- Timings for ProSel-16 are for formatted disks. Salvation formats as it writes and thus is faster with new disks. I believe that it does not verify the formatting (I could be wrong) so that verification after the write is more indicated than it is with ProSel-16. If you want to repeat the timing tests, make sure you do not time ProSel-16 using the same disks that were previously used to time Salvation. Salvation does a format when it writes and I think it is less efficient to read and write the disks it formats than for a disk formatted in the standard manner. (I did tests that indicate that, but not in a very scientific manner, so you can dismiss this statement if you like.) In any case, the last disk would not be completely formatted, and ProSel-16 would not like that much. Tests were done with formatted disks having the names used by each program. Thus neither program required any input from the user during backup. I personally am quite happy with ProSel-16, but Salvation does seem to have some good features...I leave further evaluation of Glen's comparison to the individual reader. ---------------------------------------------------------------------- Proline: rmichel@pro-grouch GEnie: R.MICHEL2 InterNet: rmichel@pro-grouch.cts.com AO: RusselM ARPA: crash!pnet01!pro-grouch!rmichel@nosc.mil UUCP: crash!pro-grouch!rmichel ARPA: crash!pro-grouch!rmichel@nosc.mil INET: rmichel@pro-grouch.cts.com