Hi, I am considering building a modest sized storage system with zfs. Some of the data on this is quite valuable, some small subset to be backed up "forever", and I am evaluating back-up options with that in mind.
My understanding is that zfs send approximately captures the copy-on-write file system block-level dump, and zfs receive plays it back to rebuild the file system, and this can be used among other things for back-ups. I call the dump "stream" below. How reliable is this? I don't mind the fact I would have to replay entire file system instead of individual files. My concern is that for whatever reason I'd lose ability to play the stream back, and would not be able to restore possibly years from now. Is the format documented? Is it possible to interpret the data with independent tools, like it's possible with tar/pax/cpio archives? Even if no such tool exists now, could I for example write a user space tool using currently existing open source zfs user space library that was able to extract useful information from the data stream? I realise this could be somewhat complex, especially incremental dumps - but just how hard? How exactly does the stream have to match the file system to restore? My assumption zfs requires an exact match: you can only restore at exact point you backed up from. (Fine by me, just need to know.) Follow-up: does one corrupted incremental back-up set invalidate all incremental back-up sets until the next full back-up point (or higher-level incremental point)? Assuming the zfs send data stream hasn't been corrupted, have there been instances where it's not possible to restore file system by playing it back via zfs receive? Have there been cases where some bug has caused "zfs send" data become corrupted so that restoration is no longer possible? (Either zfs on-disk file system bug, or something in zfs send not doing the right thing.) Is it possible to make dry-run restoration attempt at back-up time to verify the restoration would succeed? Would you recommend zfs send/receive as a back-up strategy for highly valuable data at this point in time? Ignoring the individual file vs. whole file system aspect, how reliable you rank it compared to tar/pax? Regards, Lassi _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
