On Monday 26 August 2019 21:42:29 Olivier wrote: > ghe <[email protected]> writes: > > Stan and Debra have convinced me to bite the bullet and buy a new > > tape. I've never been in this situation before (the DLT drive used > > to fail every once in a while, but a couple hours with a jeweler's > > screwdriver got it going again). > > > > Looks like I'm going to have a spare, mildly flaky, tape around. > > You mean that all your backups were on a single tape? That is beyond > daring IMHO. > > Like Gene mentioned, I have moved to disk and vtapes, never had a > problem with the disks holding the vtape, I had problems with the disk > with the holding disk though, it started develop bad blocks in the > holding disk partition, but vtapes? They are hardly used, if you > unmount/stop them after the backups are written, they can last a long > time. > > And when you need more space, you just upgrade with newer disks with > more capacity and store the old disks, so you even have offline old > stuff. > > Your slots need to be numbered starting from 1, but the tapes number > can start from the next number in sequence in your tape naming scheme, > so keep the old disks. You will change them because you need more > backup storage, not because they fail (never had since I use disks, > while I had to replace the tapes a number of times). > > I started with 7x512GB disks, then 7x1.5TB and am now at 7x3TB > and never had the slightest problem. Admittedly, the size of the > vtapes chosen at first looks a bit tiny nowdays, but with vtapes, it > really adds very little overhead, largely compensated by avoiding half > full tapes. > > When we were hit by the great flood and we had to move the datacenter, > I took the disks, but not Amanda server, as I knew I could connect the > disk directly inside any server to do a restore. > > And no fiddling with mounting and dismounting tapes every day, I have > a system with all my vtapes available all the time. > > In a similar way to what Gene described, after the dump, I get a copy > of the indexes, etc. and rsync that to a database server and mail > myself a copy, I end up with 5 or 6 copies of that critical > information (because database and mail are backed up too). > > And remeber, tapes do rub on the R/W head of the tape drive so doing > an amcheckdump does double the wear and tear of the tape. That also doubles the head wear. Since disk heads fly on a film of air that might be under a micron thick, if the disc is well finished, the only contact is at a power fail, when it has no choice but to land on the still spinning disc. Then the successfull restart depends on how long it takes to get power back. Past a month or so sitting there, the head is likely stuck to the disc like a machinists set of joe's blocks and the disc is locked from spinning up again.
I have a pair of one GB scsi drives on a trs-80 color computer that haven't been shut down for more than a couple months since about 1989, and had to dismount them so the projected 1/2" from the front of the tower they are in, power restored, and an 8oz dead blow hammer applied to the front corner enough to bump it sideways 1/8", which is enough to rotate the housing about the disc, breaking the stiction. And once the disc has moved 1/4 turn its speed supplies the air cushion under the head. That was about 2 years ago. I have a 20 kw standby thats typically up and running before the disc's have stopped, so a tap on the reset button reboots it normally. Those old drives have had since around 1989, collecting spinning hours at 8766 a year, so have close to 166554 spinning hours. Still functioning at 100%. No bad sectors. I think thats pretty decent testimony to convince anyone into never shutting a drive off They will happily outlast me. I've just spent 2 weeks in the shop from a heart attack, and still look like your grandmothers pincushion from all the taps they put in to keep me going. Currrantly its pumping around 30%, so I'm not pushing myself too hard just yet as they are building a new aorta valve they will install as a cath-lab outpatient some time next month. > No physical > contact between the head and support on disk. > > Not to mention that disks are way faster... > Generally speaking, only because the disc is random access. Actual data rate to/from the head is rarely more than one magnitude faster for the disc. And that differential is more in the teenyness of the head allowing a higher frequency than in any other magic. > Best regards, > > Olivier Copyright 2019 by Maurice E. Heskett Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene>
