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#21
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Daniel James wrote:
In article , GSV Three Minds in a Can wrote: Don't cross-post to so many groups (many people kill anything crossposted to 3 places, on the assumption that if the OP doesn't know which group it goes it, it won't be of much interest in any of them). aside .. and in doing so avoid a huge amount of junk and a few interesting discussions. I must say I'd find it "challenging" to dream up a post that could legitimately be posted to more than about five groups, but I don't think four is necessarily out of order. The OP selected four groups for a posting which seems to me to be reasonably on-topic for all of them ... except possibly uk.comp.homebuilt (which is where I'm reading it, as it happens) where it is a common enough subject fr discussion, if not strictly on-topic. /aside Back to the question .. cost per byte is not an interesting metric for backups, unless you include the cost of making the backup and the cost of securing it against whatever disaster you are backing up against. .. and, perhaps more importantly, the value of the data. People gaily make disk images of their whole system, but unless you can produce =identical= hardware this is of no use at all if your original system is stolen, ... That's a good point, and one that's not made often enough. If you have the original applications on CD, or you can buy new copies from MS, there isn't much point in wasting time and money making copies every day/week for the rest of your life. Also true. One might think -- especially give the time it takes to install some large applications -- that backing up once after an install would be a time-saver, but in general when software is installed (on Windows, that is) it sets a cartload of registry entries that aren't easily backed up in isolation. Backing up the whole registry isn't useful if disaster forces a change of hardware (which will mean the system-specific parts of the registry will no longer apply). Reinstallation is really the only safe choice. That registry is a pain in the proverbial, sometimes. For a large system a product such as Novell Zenworks can help deal with this--it takes a snapshot of the system before and after an application is installed, and after you clean up the excess baggage (something always seems to change that has nothing to do with the installation) you can quickly reinstall or install to other systems from the snapshot. It's also very nice for figuring out what actually _did_ happen during the installation when the installation hoses something. In a perfect world, RAID1 or RAID5 for continuous up-time even if a disk crashes (which they are increasingly prone to do), tape backups of anything that can't be reproduced easily .. daily ones, or weekly, or whatever turns out to be the best tradeoff between 'cost of prevention' and 'cost of recovering what you hadn't prevented being lost'. Good advice. Add to that that the daily/weekly backups (on whatever medium they're made) should be test-restored so that you can be sure that they *can* be restored, in the event of disaster (and that you've backed up everything you need). Keep a spare device that can read the backups, in case the original fails. Having a good tape backup regime is no good if, when you need to restore some old data, you find that the tape drive is knackered and that that type of drive is no longer available. You can spend a fortune on backup and still not get it right -- and you certainly can't get it all right without spending a fortune. How much you do spend must depend on the value of the data. Cheers, Daniel. -- --John Reply to jclarke at ae tee tee global dot net (was jclarke at eye bee em dot net) |
#22
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MOD/DVD-RAM (similar technology) is very good for smaller backups
with high reliability requirements. Also for long-term storage. Indeed - I use MO for just that reason, however now also use DVD-RAM: o MO media QC has blips - a few too many ---- Sony 540MB 3.5" -- block errors on new disks ---- Fujitsu own 3.5" -- block error on *same place* on every disk - factory format error o DVD-RAM has been ok - and is higher capacity ---- £ 10 will get a two-sided 9.4GB disk ---- LG-4082B will write to them once removed from the caddy Since I use DVD-RAM once-only for archive the removal from the caddy is minor. If bothered use cotton gloves - whatever - it's 15x MO capacity for the same price. MO is best for the most critical backups o It was designed for data reliability from the ground up like DLT o It is not a converted audio standard like helical scan DAT, or DVD However, the "real" MO systems are based around the 5.25" form-factor: o New blue-laser ones offer a migration path to very high data capacities o The 5.25" form factor is relatively well proven in medical/mil/industrial For the most part, DVD-RAM offers a good half-way house: o Reliability is good - it is Phase-Change unlike DVD+/-R & has better error correction o Drives are cheap - so having 2 different branded drives isn't impossible (or suppliers :-) o Disks are cheap - 9.4GB can be had for just £6.99, sealed, a bit more elsewhere MO is ~£200 drive & ~£10 media for 1.3GB v ~£60 drive & ~7 media for 9.4GB. Critical stuff is best on MO, but with those media errors I think it's forget about decades: o Yes, backup media can last a long time - DVD-RAM probably, MO most probably o However, it is perhaps more economic to keep changing technology every few yrs ---- because technology will offer more capacity, perhaps more reliability for less cost ---- that is particularly so with media cost as archives grow - eg, DVD-RAM v MO Agreed - many people backup to DVD-RAM or HDs "incorrectly" o They simply drag-n-drop files - directory is there, so it must be ok o Better to use a proper backup tool - that actually does a proper compare ---- altho even XCOPY can be forced to do a verification as I recall ---- on DVD-RAM that might be an exercise in s-l-o-w-n-e-s-s however If HDs are used, I prefer a "micro-PC" converted to NAS - with a few scripts to check the data integrity progressively to another identical machine working in parallel. That need not be particularly expensive - Mini-ITX snails don't cost much, recycle some of the older 1U PSUs, make/re-use a case, whatever. Match solution to data criticality. -- Dorothy Bradbury |
#23
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David X wrote:
What is the cost of DVD storage in the UK? I am in the UK so my figures reflect UK prices. I want to store data not music. I would welcome any comments on my posting. (1) I can buy a 160GB hard drive for approx £65 including delivery. (E.G. Maxtor Plus9 160GB 8MB 7200rpm from Dabs). The available formatted space on the HDD is about 150GB (in 4K block with NTFS), so this comes to 41p per GB. Sustained data transfer rates are fast (about 15 MB/s according to http://storagereview.com/map/lm.cgi/str and http://www.pcguide.com/ref/hdd/perf/extSpeed-c.html) so the process of getting data to or from the HDD is relatively quick. (2) For CDs (not DVD) I would say the usable storage space is approx 500MB (not 750 or 800 because it is rare to completely fill a CD and I believe there is approx 10 percent used for error correction). I don't know what block size is used. I want to have a protective case and not use the very cheapest product. 100 cased CD-Rs is approx £22 including delivery. I need 300 to match 150GB so the total cost is £66. This excludes costs for the CD-R burner. Data transfer rates when reading are not bad at about 3 MB/s (according to http://www.pcguide.com/ref/cd/perfTransfer-c.html). (3) DVDs. Now this is new to me. Are the following reasonable assumptions. Cased DVD+R or DVD-R 8x blanks are about £0.50 each (?). What does the nominal 4.7Gb actually hold when data is stored? Is the block size relatively large? What is the cost per GB assuming the disk is only 80% filled? Overall, I get the impression that HDDs are a far better and cheaper way of backing up data for the home user. The HDD can be re-used and if the HDD is plugged in (which can be harder than inserting a DVD) then the availability is almost instantaneous. Well, consider also backing up to an online server. You can get a Gigabyte of space for about $10 per month. What I'm going to do is write a script that encrypts my most important files, and then sends them by ftp to the online server. Then, I keep the secret key file on only on a CD. This way, I can keep the encrypted backup files in relatively non-secure locations, and keep only a minimal amount of data on physical CDs. The public key is stored anywhere I need to create encrypted files. Here's an article on how to use gnupg to do this: http://www.somacon.com/blog/page7.php |
#24
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In comp.sys.ibm.pc.hardware.storage Dorothy Bradbury wrote:
MOD/DVD-RAM (similar technology) is very good for smaller backups with high reliability requirements. Also for long-term storage. Indeed - I use MO for just that reason, however now also use DVD-RAM: o MO media QC has blips - a few too many ---- Sony 540MB 3.5" -- block errors on new disks ---- Fujitsu own 3.5" -- block error on *same place* on every disk - factory format error o DVD-RAM has been ok - and is higher capacity ---- £ 10 will get a two-sided 9.4GB disk ---- LG-4082B will write to them once removed from the caddy Since I use DVD-RAM once-only for archive the removal from the caddy is minor. If bothered use cotton gloves - whatever - it's 15x MO capacity for the same price. Well, not quite. The last time I bought 3.5" 640MB MOs, I paid 5 Euro for each. The cheapest DVD-RAM I find is the same price for 4.7GB. That is a factor of 7. Still signifficant if you do large backups. MO is best for the most critical backups o It was designed for data reliability from the ground up like DLT o It is not a converted audio standard like helical scan DAT, or DVD I agree. In 7 years regular MO usage I have still to see my first unrecoverable read error. (I had to clean cartridtges two times, but that resolved the problems with them completely.) However, the "real" MO systems are based around the 5.25" form-factor: o New blue-laser ones offer a migration path to very high data capacities o The 5.25" form factor is relatively well proven in medical/mil/industrial Actually many hostpitals in Europe use 3.5" MOD for computer images. They have to keep the info for 20years by law, e.g. in Germany or Switzerland and a few of these 640MODs are enough for a day. I would say 3.5" MOD is professional today. 5.25" MOD seems to have stalled development some time ago. For the most part, DVD-RAM offers a good half-way house: o Reliability is good - it is Phase-Change unlike DVD+/-R & has better error correction o Drives are cheap - so having 2 different branded drives isn't impossible (or suppliers :-) o Disks are cheap - 9.4GB can be had for just £6.99, sealed, a bit more elsewhere However there is the cartridge issue. Drop a DVD-RAM and it may be gone. A MOD does not care. Also remember that MOD has 30 Million certified overwrites while DVD-RAM without cartridge only has 10.000. If you only do backups, that does not matter much. I also use my MODs in "HDD mode", i.e. move around files, do small changes, etc.. MO is ~£200 drive & ~£10 media for 1.3GB v ~£60 drive & ~7 media for 9.4GB. Critical stuff is best on MO, but with those media errors I think it's forget about decades: o Yes, backup media can last a long time - DVD-RAM probably, MO most probably o However, it is perhaps more economic to keep changing technology every few yrs ---- because technology will offer more capacity, perhaps more reliability for less cost ---- that is particularly so with media cost as archives grow - eg, DVD-RAM v MO Depends. I have still about the same needs for high-reliability backups. After I nearly lost some important stuff 7 years ago, I got a 640MB MO drive. I still get my system and home backups on just two of these disks and I still have all the original disks and the original drive in use without problems. The last time I bought disks is 3 years ago, the ~30 GB ultra-reliable storage I have is more than enough. For the less critical stuff I keep copies on other computers. MOD is fit to keep you Master's thesis, family photos, tax data you need to store for decades (in some countries), scans of your degree, in short all the things you absolutely do not want to loose. Also most data recovery companies will convert MOD to some other format for you for a modest fee and that type of offer should be around really long. So even if you do not have a drive anymore in 30 years, that data should still be accessible. If your storage needs grow fast (my orgiginal complete systems backup fit on just one 640MB MOD), then MOD is not the right solution today. (It was by far the cheapest 7 years ago. And it is still around. That should tell you something.) Agreed - many people backup to DVD-RAM or HDs "incorrectly" o They simply drag-n-drop files - directory is there, so it must be ok o Better to use a proper backup tool - that actually does a proper compare ---- altho even XCOPY can be forced to do a verification as I recall ---- on DVD-RAM that might be an exercise in s-l-o-w-n-e-s-s however Actually you should script this stuff. I am still surprised that MS does not deliver a proper and easy to use backup tool with thir OS. It is not that difficult. I use unix tar, perhaps one of the oldest UNIX tools with good success. If HDs are used, I prefer a "micro-PC" converted to NAS - with a few Yes, that is what I use at home for the less critical stuff. A Mini-ITX box with a 120GB HDD is just fine for this. scripts to check the data integrity progressively to another identical machine working in parallel. That need not be particularly expensive - Mini-ITX snails don't cost much, recycle some of the older 1U PSUs, make/re-use a case, whatever. Match solution to data criticality. .... and to data amounth and actuallity. Only then will you get something satisfactory. Arno -- For email address: lastname AT tik DOT ee DOT ethz DOT ch GnuPG: ID:1E25338F FP:0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F "The more corrupt the state, the more numerous the laws" - Tacitus |
#25
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phorbin wrote:
In article , lid says... "Sideshow" wrote: A raid0 or raid5 array is the most suitable option for long term backup, as if one drive fizzucks you can just replace it with a new one without any data loss. Sure, a small company I know decided a raid array on their server meant they didn't need to backup. The sever fell over one day and trashed the whole array, they lost everything. Hard drives inside an active machine are a very bad idea for long term backup. Fell over??? As in dropped to the floor? Fell over as in stopped working properly - I don't know the details Personally I have seen Win2k trash a (cheap) stripped array because one of the drives was a bit sticky on power up. The RAID BIOS didn't recognise the set and w2k thought the remaining drive was corrupt and attempted to 'fix' it on boot without any operator intervention. A RAID 0/5 protects you against drive failure, it offers no protection against all the other ways data can be lost. |
#26
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nospam wrote:
"Sideshow" wrote: A raid0 or raid5 array is the most suitable option for long term backup, as if one drive fizzucks you can just replace it with a new one without any data loss. Sure, a small company I know decided a raid array on their server meant they didn't need to backup. The sever fell over one day and trashed the whole array, they lost everything. Hard drives inside an active machine are a very bad idea for long term backup. Also, FILES get corrupted or otherwise damaged without affecting the hard disc. It's very nice to have a week's daily backups and a month's weekly backups on tape (9 tapes). Best wishes, -- Michael Salem |
#27
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#28
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#29
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In message , Michael
Salem writes nospam wrote: "Sideshow" wrote: A raid0 or raid5 array is the most suitable option for long term backup, as if one drive fizzucks you can just replace it with a new one without any data loss. Sure, a small company I know decided a raid array on their server meant they didn't need to backup. The sever fell over one day and trashed the whole array, they lost everything. Hard drives inside an active machine are a very bad idea for long term backup. Also, FILES get corrupted or otherwise damaged without affecting the hard disc. It's very nice to have a week's daily backups and a month's weekly backups on tape (9 tapes). Pretty much essential. In my experience the main use for backup tapes is to restore files that users have deleted. A RAID array doesn't protect against that. In fact I haven't ever needed to use a backup tape for any other purpose, and I've been working with computers for 25 years. -- Bernard Peek London, UK. DBA, Manager, Trainer & Author. Will work for money. |
#30
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In message , Arno Wagner
writes Agreed - many people backup to DVD-RAM or HDs "incorrectly" o They simply drag-n-drop files - directory is there, so it must be ok o Better to use a proper backup tool - that actually does a proper compare ---- altho even XCOPY can be forced to do a verification as I recall ---- on DVD-RAM that might be an exercise in s-l-o-w-n-e-s-s however Actually you should script this stuff. I am still surprised that MS does not deliver a proper and easy to use backup tool with thir OS. They do. If you understand how to write batch files you can use ntbackup to do complex scripted backups. It's a very powerful tool but almost completely undocumented. -- Bernard Peek London, UK. DBA, Manager, Trainer & Author. Will work for money. |
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