} -----Original Message----- } From: linux-raid-owner@xxxxxxxxxxxxxxx [mailto:linux-raid- } owner@xxxxxxxxxxxxxxx] On Behalf Of Thomas Fjellstrom } Sent: Sunday, October 25, 2009 1:26 AM } To: linux-raid@xxxxxxxxxxxxxxx } Subject: Re: Is My Data DESTROYED?! } } On Sat October 24 2009, Leslie Rhorer wrote: } > > On Sat, Oct 24, 2009 at 6:52 PM, Leslie Rhorer <lrhorer@xxxxxxxxxxx> } > > } > > wrote: } > > >> I'm going to go on a limb here and say for anyone (with data they } want } > > >> to preserve), no matter what, backups make sense and are cost } > > >> effective. I'm going to be crazy and say that there's no reason } that } > > >> someone who thinks they can afford a 8TB disk array and dual SLI } video } > > >> cards, etc, etc, can't also consider some sort of disk or tape } backup. } > > > } > > > I agree with the disk backup, but not the tape. } > > > } > > >> Cumbersome? Can be. But having worked with datasets and filesystems } > > > } > > > Cumberesome, slow, kludgy, and expensive. } > > } > > Well, like anything else, having a system helps. And by system I mean } > > a library, barcodes on all tapes, and a good tape storage system. Yes, } > > it involves Humans. } > } > Well, that wasn't quite my point, but it is another aspect of the } > issue. } > } > > >> that run into the hundreds of terabytes, and having backed them up } to } > > >> tape, it makes sense. If you have something on the order of tens of } > > >> disks, sure, go ahead, take that next step and back them up } somewhere } > > >> else to another set of disks. If you have more disks, seriously } > > >> consider tape--in terms of capacity and power consumption (and data } > > >> integrity), tape wins. } > > > } > > > Power consumption, yes. Capacity is a somewhat more complex } > > > problem, with a number of variables. For speed, tapes lose } > > } > > disastrously. } > > } > > > For cost, hard drives win unless the array is very large. For } > > } > > reliability } > > } > > > and availability, drives win hands down. I've had quite a bit of } data } > > } > > lost } > > } > > > with bad tape sets, and the most persistent problems on my systems } > > > which } > > } > > do } > > } > > > use tapes involve the tape drives, even sans data loss. Once } someone } > > } > > wiped } > > } > > > out a directory which someone up in corporate was backing up to } tape. } > > } > > It } > > } > > > took 3 days to recover the directory, no doubt because no one could } > > > find } > > } > > the } > > } > > > tape. } > > } > > I'm not so sure about the speed--you can stream 100MB/sec to a single } > > tape drive, and if you have multiple in a library, it just scales } > > horizontally. } > } > First of all, that assumes the tape is loaded and ready. It can } > take hours or even days to retrieve a tape and load it. Secondly, while } > the tape can stream 100MB/sec, it isn't random access. Finding a 200 } byte } > file in the middle of a 1T tape backup is going to take a while. } Getting } > it from an online backup server takes perhaps 10ms after the admin } > finishes typing the copy command. } } Wouldn't you use some 'tar' like format on the tape so there's a file } index } you can search without having to scan the entire tape? Then you can just } "ffwd" (seek) to the position. _should_ be lots faster than reading all of } the } data from the beginning to the files location trying to find it. Or maybe } there's something I'm missing about tapes? tar does not have an index. The file name comes just before the file. I use cpio and gzip. But I write to a USB disk. I have restored 1 file, and it had to scan through the data to find the file. But back to your point. I don't know of any open source software that can restore a file quickly from tape. And with a disk backup, if you use a file system you can restore quickly. But a file system wastes space. That is why I use cpio and gzip. I backup about 500GB to a file about 350GB. But it really depends on how well your data compresses. } } > > But, where I was working, we were also duplicating tape sets for } > > offsite, which means there was two copies per backup set. } > > } > > Is this expensive? You betcha! But...you know. The bad old days of DDS } > > are also gone, so there's some rejoicing there. } > } > They may be for you. I have to manage over 300 of the beasts on the } > same number of hosts. What's worse, not only are the backups themselves } > often incompatible, the drives often can't even use the same tapes. I } have } > to see to it a half dozen different tape types get stocked in 75 } different } > cities. Then I have to try to make sure the gopher in every city } remembers } > to replace the tape. } } :( } } > -- } > To unsubscribe from this list: send the line "unsubscribe linux-raid" in } > the body of a message to majordomo@xxxxxxxxxxxxxxx } > More majordomo info at http://vger.kernel.org/majordomo-info.html } > } } } -- } Thomas Fjellstrom } tfjellstrom@xxxxxxx } -- } To unsubscribe from this list: send the line "unsubscribe linux-raid" in } the body of a message to majordomo@xxxxxxxxxxxxxxx } More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
