Re: [zfs-discuss] Backup in general (was "Does ZFS handle a SATA II ' port multiplier' ?")
[EMAIL PROTECTED] wrote: >>> If you care enough to do backups, at least care enough to be >>> able to restore. For my home backups, I use portable drives with >>> copies=2 or 3 and compression enabled. I don't fool with >>> incrementals, but many people do. The failure mode I'm worried >>> about is decay, as the drives will be off most of the time. The >>> copies feature works well for this failure mode. >>> >> I am definitely and strongly interested in restoring! That's why I hate >> my previous backup solutions so much (NTI backup and then Acronis True >> Image); I verified backups and tested restores, and had *FAR* too much >> trouble to be at all comfortable. The photos and the ebooks are backed >> up eventually (but not always within the month) to good DVDs, and one >> copy is kept off-site, and that's the stuff I'd miss most if it went, >> but I want a good *overall* solution. >> >> The "copies" thing sounds familiar from discussion here...ah. Yes, >> that's exactly perfect; it lets me make up a batch of miscellaneous >> spare disks totaling enough space, each one a vdev, put them into one >> pool (no redundancy), but with copies=2 get nearly the redundancy of >> mirroring which would have required matching drives. At least, if I >> > > >From what I have seen I think you are over estimating the value of > copies=x. copies=X are guaranteed to store multiple copies (X) of the > blocks _somewhere_ in the pool, but not necessarily on different disks. > So while you may gain mirror like protection when you have failed blocks on > a disk (maybe -- blocks could be too close together on the same disk); you > do not necessarily gain that from a failed disk (block copies could be on > only one disk). Having different sized unprotected disks and using copies=N > has less mirror like effect over time and fragmentation of those disks. > > http://blogs.sun.com/bill/entry/ditto_blocks_the_amazing_tape > http://blogs.sun.com/relling/entry/zfs_copies_and_data_protection > Yes, that's quite clear even just from the man page. That's why I said "nearly"; I understand that "copies < mirrors", as you put it. Not *necessarily* on different disks, but it *tries* to put it on different disks. "Over time" isn't necessarily an issue, since a new full backup could be done into a clean filesystem. -- David Dyer-Bennet, [EMAIL PROTECTED]; http://dd-b.net/ Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/ Photos: http://dd-b.net/photography/gallery/ Dragaera: http://dragaera.info ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Backup in general (was "Does ZFS handle a SATA II ' port multiplier' ?")
> > > > If you care enough to do backups, at least care enough to be > > able to restore. For my home backups, I use portable drives with > > copies=2 or 3 and compression enabled. I don't fool with > > incrementals, but many people do. The failure mode I'm worried > > about is decay, as the drives will be off most of the time. The > > copies feature works well for this failure mode. > > I am definitely and strongly interested in restoring! That's why I hate > my previous backup solutions so much (NTI backup and then Acronis True > Image); I verified backups and tested restores, and had *FAR* too much > trouble to be at all comfortable. The photos and the ebooks are backed > up eventually (but not always within the month) to good DVDs, and one > copy is kept off-site, and that's the stuff I'd miss most if it went, > but I want a good *overall* solution. > > The "copies" thing sounds familiar from discussion here...ah. Yes, > that's exactly perfect; it lets me make up a batch of miscellaneous > spare disks totaling enough space, each one a vdev, put them into one > pool (no redundancy), but with copies=2 get nearly the redundancy of > mirroring which would have required matching drives. At least, if I >From what I have seen I think you are over estimating the value of copies=x. copies=X are guaranteed to store multiple copies (X) of the blocks _somewhere_ in the pool, but not necessarily on different disks. So while you may gain mirror like protection when you have failed blocks on a disk (maybe -- blocks could be too close together on the same disk); you do not necessarily gain that from a failed disk (block copies could be on only one disk). Having different sized unprotected disks and using copies=N has less mirror like effect over time and fragmentation of those disks. http://blogs.sun.com/bill/entry/ditto_blocks_the_amazing_tape http://blogs.sun.com/relling/entry/zfs_copies_and_data_protection copies < mirrors. > find a solution for connecting that bunch of disks conveniently. I > really want one box with easily swappable disks, and one cable. (And > then two of them, since of course I need two sets of backup media to > alternate between.) And I could update the old full backup to become > the new one using rsync locally, perhaps much faster than doing a full CP. ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Backup in general (was "Does ZFS handle a SATA II ' port multiplier' ?")
Richard Elling wrote: > David Dyer-Bennet wrote: >> >> I'm interested in the same question. I'm looking at what to use for >> backup from my Solaris file server. I've had rather bad experiences >> with external Firewire and USB disks, especially in performance >> (can't be absolutely sure the problem isn't with Windows there, >> though, or even the specific backup software). So I'm wondering if >> using the eSATA port to connect to an external enclosure with >> multiple drives in it might be a winning strategy. Two external >> enclosures, alternate monthly for a full backup, say. I'm tempted to >> use ZFS on a random selection of disks with no redundancy, as a way >> to keep costs down. This does of course multiply the chance of a >> drive going bad and invalidating a big chunk of the backup just when >> it hurts most. >> > > If you care enough to do backups, at least care enough to be > able to restore. For my home backups, I use portable drives with > copies=2 or 3 and compression enabled. I don't fool with > incrementals, but many people do. The failure mode I'm worried > about is decay, as the drives will be off most of the time. The > copies feature works well for this failure mode. > I am definitely and strongly interested in restoring! That's why I hate my previous backup solutions so much (NTI backup and then Acronis True Image); I verified backups and tested restores, and had *FAR* too much trouble to be at all comfortable. The photos and the ebooks are backed up eventually (but not always within the month) to good DVDs, and one copy is kept off-site, and that's the stuff I'd miss most if it went, but I want a good *overall* solution. The "copies" thing sounds familiar from discussion here...ah. Yes, that's exactly perfect; it lets me make up a batch of miscellaneous spare disks totaling enough space, each one a vdev, put them into one pool (no redundancy), but with copies=2 get nearly the redundancy of mirroring which would have required matching drives. At least, if I find a solution for connecting that bunch of disks conveniently. I really want one box with easily swappable disks, and one cable. (And then two of them, since of course I need two sets of backup media to alternate between.) And I could update the old full backup to become the new one using rsync locally, perhaps much faster than doing a full CP. So how do I get introduced to SAS, and how does that relate to SATA, and where does "infiniband" come in (I know of that one only in terms of huge expensive switches, does it actually apply to home disk setups at all?)? I'm going to start with Wikipedia tonight, and then see what people suggest for further information. -- David Dyer-Bennet, [EMAIL PROTECTED]; http://dd-b.net/ Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/ Photos: http://dd-b.net/photography/gallery/ Dragaera: http://dragaera.info ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Backup in general (was "Does ZFS handle a SATA II ' port multiplier' ?")
David Dyer-Bennet wrote: > > I'm interested in the same question. I'm looking at what to use for > backup from my Solaris file server. I've had rather bad experiences > with external Firewire and USB disks, especially in performance (can't > be absolutely sure the problem isn't with Windows there, though, or even > the specific backup software). So I'm wondering if using the eSATA port > to connect to an external enclosure with multiple drives in it might be > a winning strategy. Two external enclosures, alternate monthly for a > full backup, say. I'm tempted to use ZFS on a random selection of disks > with no redundancy, as a way to keep costs down. This does of course > multiply the chance of a drive going bad and invalidating a big chunk of > the backup just when it hurts most. > If you care enough to do backups, at least care enough to be able to restore. For my home backups, I use portable drives with copies=2 or 3 and compression enabled. I don't fool with incrementals, but many people do. The failure mode I'm worried about is decay, as the drives will be off most of the time. The copies feature works well for this failure mode. -- richard ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] Backup in general (was "Does ZFS handle a SATA II ' port multiplier' ?")
Lars Tunkrans wrote: > Anyone tried to use ZFS with this type of box ? . The new thing about this > one is that >it contains a1x eSATA to 4x SATA Port multipler > > > http://www.stardom.com.tw/sohotank%20st5610-4s-sb2.htm > There won't be a ZFS issue; ZFS talks to any kind of Solaris block device, right? The question is, will Solaris handle this concept, and this particular implementation. I'm interested in the same question. I'm looking at what to use for backup from my Solaris file server. I've had rather bad experiences with external Firewire and USB disks, especially in performance (can't be absolutely sure the problem isn't with Windows there, though, or even the specific backup software). So I'm wondering if using the eSATA port to connect to an external enclosure with multiple drives in it might be a winning strategy. Two external enclosures, alternate monthly for a full backup, say. I'm tempted to use ZFS on a random selection of disks with no redundancy, as a way to keep costs down. This does of course multiply the chance of a drive going bad and invalidating a big chunk of the backup just when it hurts most. I've also considered buying two Drobos for this, but as a USB device I think of it as painfully slow. But it would let me stick my spare drives into it in random combinations and give me redundant protection on my backups. If I were using a single drive, I'd accept the risk of it failing, but when I'm using three or four drives, I'm not so sanguine about it. I could buy two 750GB external drives and just back up to those, for a while longer (and then presumably move those drives into the server, and get something even bigger for the backup drives; but in the long run I don't think it's smart for me to count on always using a single drive for each backup). Tape drives and tapes seem to be just too expensive. Am I out of date here? What would I need to buy to back up a system that currently has about 600GB of data in it, growing a few GB a month on average? (Digital photos; not as bad as if I were recording HD video, but still pretty bad at about 9MB a shot for the camera originals). Also, what *software* does one use? For a full, and for an incremental? One obvious idea is to just cp -a to the drive for a full backup. This leaves each file easily findable and individually accessible, which is good. ZFS can give me a view equivalent to an incremental, can't it? Which I could then copy somewhere suitable? -- David Dyer-Bennet, [EMAIL PROTECTED]; http://dd-b.net/ Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/ Photos: http://dd-b.net/photography/gallery/ Dragaera: http://dragaera.info ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
