Big -- Cheap -- Reliable.. pick any two.
Best regards, Spehro Pefhany
-- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
Indeed, dead drives don't leave out facilities in one piece, they get shredded first. Drives that are good but retired used to get wiped, I'm not sure if they still do that or just shred them as well.
If your usage is read-intensive RAID 5 can be attractive. On writes there's a performance hit unless you have a controller with dedicated hardware to do the parity calculations and parity writes. For general use a mirror is generally a better option unless you need a huge amount of storage.
Yeah, grumble, grumble, having two copies sure cuts into the cost advantage of recording TV shows vs buying the DVDs. I'm gambling that rarely used backup drives will have a looong lifetime if they survive a few days of burn-in testing. jsw
One of my three external drives hickup'ed and I lost a bunch of movies.
It's going to happen.
So backing up to DVD is necessary...
Drives are cheap, mirror them. There are some nice little external USB/FW two drive enclosures available that do mirroring.
Problem is that DVDs only hold 4.7G. It takes 7 of them to back up a medium sized USB drive, and over 400 of them to back up a full 2T drive. Not practical.
I grew up on A and B drives at 525k, so it seems odd that people say "only 4.7 GB".
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Problem is that DVDs only hold 4.7G. It takes 7 of them to back up a medium sized USB drive, and over 400 of them to back up a full 2T drive. Not practical.
8" drives for me, youngster. Incredible to think that the old IBM 360K 5.25" disks would fit 13,000 to a DVD, but almost 100,000 to the card in my inexpensive digital camera. And 8 million to a 3T HDD you can buy for a mere $150.00. Drives cost more than that in mid-70s dollars, so the improvement is probably close to 8 orders of magnitude.
And here I am struggling to get one measly order of magnitude improvement in things..
The problem is that an hour of 1080i is larger than a single layer DVD can hold, and good DLs are rare and expensive.
The shows I recorded will hopefully be trimmed someday by cutting commercials and extracting the few good performances from 3-hour music awards shows and DWTS. The first step was setting up a widescreen laptop as a TV + DVR + video editor next to my comfortable reclining chair. My big living room TV is an old analog one on a converter box. It's much better than the LCD ones for aiming the antenna at the strongest signal and has nicer colors but is not so good with the computer.
jsw
What do you do when one of the two drives fails?
I confirm that my two individually written backups are identical by comparing their folder sizes, and sometimes lining up the directory listings side by side to check that the top or bottom file names in each column in both windows match. That will catch one file missing from a folder of hundreds and quickly lead to its name. Sorting by size or date can help too. Delete thumbnails which throw the folder sizes off.
FWIW, I've settled on pairs of 2TB external drives for backups as a compromise between cost per terabyte and time to read or write them, especially when racing a drive that's started to cough. Now that I have a USB3 card that can copy a 2TB drive in less than a day larger drives may make more sense than they did with USB2.
jsw
I started with 512 -bytes- of memory and Teletype paper tape for mass storage. The first hard drive I was asked to check out held 5 whole MegaBytes and had only rudimentary step and direction inputs and no r/w electronics, just wires to the head coil. How far we have come! jsw
Avoid WD Green drives like the plague. Avoid other WD drives like the flu.
That only leaves Seagate because the two of them bought everyone else.
Enterprise drives are better of course, but with Linux you can do software RAID on your boot drive (Windows only does software RAID for data drives), and two regular drives are better than one enterprise drive, are faster, and may cost less.
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Er, did you read what I said? Mirror the HDDs, forget DVD backups, even Blu-Ray doesn't cut it for capacity. Enterprise class backups are all going disk based with data de-duplication.
That's 4.7GB per layer for ordinary DVD. With Bluray, it goes up to about 25GB per layer. Add more layers, and the current science fiction drives will deliver 1TB per platter:
In the bad olde daze, I used QIC tape drives with capacities from 20MB up to about 1GB (with compression). Then came DAT to 8GB. DAT gets my award for maximum complexity delivering the least reliability. Then came various DLT/DLT-V/SDLT/DLT-S mutations up to about 110GB which was an improvement. A clue is that about 25%(?) of what's written to the tape is error correction data. Anyway, if you don't like layer cake platters, you can always try tape.
My solution is a combination of partition imaging software and rsync type copy programs to a live replicating server. If one goes down, the other one can be kick started with minimal loss of time and data. Typically, I can backup to a USB 2.0 plug in drive at 1-2 GB/minute. A typical 50GB of live data on a workstation takes 30-45 minutes to backup literally everything on the drive. After several disasters, I've settled on Acronis True Image Home 2012.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
RAID 0+1 with parity partly takes care of that. There are two pairs of drives that are both striped (for speed) and mirrored (for reliability). The 5th drive handles the parity. I maintained several of these mission critical servers during the mid 1990's.
However, there's a problem. The drives from the 1990's were not very reliable. Certain that a drive failure would be inevitable, I elected to put some spare drives on the shelf just to have them when needed. This was possible because the customer had about 40 spinning drives and the added cost of putting 2-4 on the shelf was not too horrible.
Sure enough, one drive indicated that there was a problem, so I used one of the replacements to fix it. Then another in the same machine which was also replaced. When the third drive died, I knew I was in trouble. It wasn't one of the remaining two operating drives, it was the one I had just replaced. I rebuilt the filesystems with two new drives (from a different vendor) using just RAID 1 (mirroring) and held my breath.
Meanwhile I tested the old drives. All 4 spare drives showed indications of failing. Had I not known the history, I would have called them identical in failure mode compared to the drives that had been running for about a year in the machine. Even the two drives that had never been in any machine were failing. Is there a self-destruct timer built into the drives that blows just after the warranty expires?
My conclusion was that the life of the drive was the same whether the drive was running or just sitting on the shelf. I took up the issue initially with Compaq, who supplied the drives, and later with Seagate, who manufactured the drives. Neither was particularly interested or helpful.
So, with RAID, the chances are that:
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Will it clone a Windows 7 boot drive?
jsw
Green sucks, but I've done OK with Blue and Black. See my other postings in this thread.
It was more of a bailout than a buyout. Most of them didn't have a clue how to make cheap and reliable drives.
I have a customer that doesn't want to deal with any drive failures. So, in about 2009, when it was time to replace all the old junk with new junk, I ordered three Dell Optiplex 755 machines with "premium high reliability" disk drives. These turned out to be made by Samsung. Within a year, two of them had failed and I had to do a pre-emptive replacement on the other one because S.M.A.R.T. was announcing potential problems. So much for premium drives.
My favorite drive manufacturers name: True to its name, it died young.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Sure: It also gets the disk signature. I think (not sure) that 2012 will do Windoze 7 but not Windoze 8. For Windoze 8, I think (not sure) you need the latest 2013 version. I just downloaded the upgrade, but haven't had time to try it on any Windoze 8 machines. I did have some weirdness with the hidden (reserved) partition but that was fixed with an update.
UEFI Secure Boot under Windoze 8 will be the big mystery. I won't be able to try it until someone actually buys a machine with a UEFI BIOS for me to play with. I can wait and let someone else do the testing.
Note: I do all my backups from the bootable backup/restore CD produced by Acronis. I do not try to backup a partition while Windoze is running.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
What indications; seek errors, retries, ECC, a rising pending or reallocated count?
jsw
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