I don't agree full with your argument. First of all, when changing backup/restore platforms, be that the machine being backed up, the tool backing it up, or the medium backed up to, you must put in place a procedure for legacy restores. If part a requirement of your legacy restore plan is that you need to keep one of that OS, tool, or tape drive around, then you have to keep it around. That's why we have a BudTool server, a machine running Novell NetWare, and a whole host of old, weathered tape drives. =)
i agree completely that legacy restores need to be addressed, and i too have my collection of old tape drives. i fully anticipate having to maintain
1) software that reads the media 2) hardware into which the media fits
after that i shouldn't have to care about the h/w involved in the original data. i even extend that to OS, but conceed that that extension is arguable.
On the other hand, I agree with you that it would be nice if all new technologies were fully backwards compatible. It would also be nice if all
no. i never said that i wanted new technologies to be fully backwards compatible. i don't expect ndmp to read tar, or cpio or even dump. but i don't expect a software vendor to force me to maintain storage h/w long after it or even the company is no longer available.
i have VMS tapes. i don't have a VMS system. but before i lost access to the VMS system i ensured that i had a piece of s/w that would allow me to read the tapes.
i have NeXT tapes. i can read these tapes - 7 years old off a [mostly] dead vendor - on my solaris box. i don't care that the disk format was afs, 4.3, ufs or whatever. i have Tops-10 tapes. if i want to read them, then it is my responsibility to get s/w that will read tops-10 tapes. you get the idea.
tape backup s/w should be disk media independant.
let's say it's 10 years from now. my disk vendor "JaBOD" has gone away a while ago and i've moved to netapps. i have a fire at my site. all my machines are gone. i pull out the DRP and get the backup tapes from offsite. but wait - that "JaBOD" filer i was keeping around for recovery is a pile of molten bits. oops.
should i be required to keep a "JaBOD" filer with my offsite tape storage? if so, that also means i have to move it onsite periodically to test it out - monthly? annually? physically moving equipment regularily is a nice recipe for breaking them. we need to minimize the h/w reliances not expand them.
Veritas cannot guarantee this in any way. NetBackup only knows that it wrote a big long stream of blocks to tape, and it receives a chunk of file history aimed at helping us humans figure out what files are in there. NetBackup doesn't know if that long stream of blocks was NetApp dump format, tar format, cpio, or otherwise. In NDMP, it is the responsibility
having the backup s/w open a stream to the tape and then having the filer dump to is is an inspired idea. really. i think it's fast, slick and a "good thing (tm)".
it's the restore that worries me. the format of the data on tape is not a secret. the filer company that wrote their NDMP dump/restore certainly knows it.
filer companies and backup vendors are very happily and loudly proclaiming their relationships and working partnerships. IMNSHO part of that partnership should either be the format of the data stream or routines to manipulate it. either way would provide a h/w independant restore to happen. is this good for the filer company - on the surface no because it allows my backups to be moved to another filer company's product.
if i liked closed systems, i wouldn't have spent the last 20 years with adventures in unix-land.
i brought this h/w reliance up with a backup vendor. their response was (and i paraphrase): "our backup s/w is intended to handle short term recovery - our s/w is not intended for long term recovery. you should use archival s/w for long term storage."
pretty scary stuff.
-- email: lance_bailey@pmc-sierra.com box: Lance R. Bailey, unix Administrator vox: +1 604 415 6646 PMC-Sierra, Inc fax: +1 604 415 6151 105-8555 Baxter Place http://www.lydia.org/~zaphod Burnaby BC, V5A 4V7 Canada: Not quite as boring as you think. -- Crazy People