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WD10EARS (wd green drive) in raid 1 (mirroring)?

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March 20, 2010 11:47:25 PM

Hi, I'm thinking about backup, and RAID 1 seems to be good idea; not only is my data safe (two disk failing at once is kind of impropable; atleast, that's the acceptable risk), also I will get ~2xread performance.
However, I heard that these drives don't have TLER function enabled, and there's no way around it. Will raid 1 work? Does anyone here have WD10EARS in RAID?

This drive has 4kb sector's, I don't know if that's an issue with raid controller or not. My motherboard is http://www.gigabyte.eu/Products/Motherboard/Products_Sp...

I was unable to find good answers in google, other than this isn't the perfect hd for raid.
a c 415 G Storage
March 21, 2010 12:02:38 AM

alamakota said:
Hi, I'm thinking about backup, and RAID 1 seems to be good idea


WRONG. For backup, RAID 1 is a BAD IDEA.

If you're really worried about your data, take that second disk and use it in an external enclosure for backup. Even better, get a third disk and use it to alternate backups and keep the most recent backup offsite. That way you'll be able to recover your data no matter WHAT happens.
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March 21, 2010 1:25:09 AM

sminlal said:
WRONG. For backup, RAID 1 is a BAD IDEA.

Why? I know that this doesn't protect me from fire/psu frying whole pc/etc. However, (single) hd failures are the most common reason for data loss (anegdotal evidence, but I don't think this isn't the truth).
I don't need perfect backup; raid 1 is a sufficiently good one, considering faster read speeds and always up-to-date backup.
I just want to know if this particular drive will work in raid 1, as I heard that it has important function artifically blocked (product segmentation).

I don't want protection against human error (wrong file deleted etc) or software's. Just physical failures.
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a c 415 G Storage
March 21, 2010 1:50:25 AM

Then what your asking for isn't backup - just as long as you're clear on that.

Although I'm a little confused as to why you'd be concerned with drive failure if you're not concerned about all those other risks. I've personally never had a drive failure, but I have had to restore data from backups for other reasons. I mean no malice when I say that someone who thinks all those other risks won't happen to him is very naive.

The EARS drives should work just fine in RAID 1, although without TLER they may be a little more prone to dropping out of the array when doing bad block error recovery. Just be careful about partitioning them so that the sectors end up aligned properly so as to avoid performance issues.

Don't expect miracles in terms of read performance. Access times with RAID 1 are really not a whole lot better than with an ordinary disk, and you may or may not get better transfer rates depending on how smart the controller is.
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March 21, 2010 1:14:54 PM

I had 5 drive failures during the years, the last one being a notebook's hd making weird noises (trying to spin and failing) during startup; the last time I used it I had to physically punch it (after fourth restart) and it finally ran.
(weird noises were a early warning so i already had important data backed up).
However, I never had any data loss because of non-physical failure; I never had a non-physical failure of any kind. Suddenly expecting one would be just paranoid.

Thank you for your answer about TLER.
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a c 415 G Storage
March 21, 2010 3:29:55 PM

alamakota said:
I had 5 drive failures during the years...

I never had a non-physical failure of any kind. Suddenly expecting one would be just paranoid.


I've you've had 5 drive failures then I think you have good reason to be paranoid... :( 
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April 2, 2010 1:47:41 PM

alamakota said:
Will raid 1 work? Does anyone here have WD10EARS in RAID?




I do. So far, I have not had issues but I'm worried after reading on the WD website that these drives are not RAID compatible (Whatever that means. Maybe the TLER thing).

The thing for me is though, the Advanced Formatting Tool would not see my RAID array and the drives speeds are slow if I don't use that Advanced Formatting Tool(normal). So, I had to install the drives as single devices > run the Advanced Formatting Tool on one drive at a time > copy my data to one of the two drives > and then use the Intel utility to 'create an array from an existing hard drive' on the Intel RAID software utility. Then, my drive speeds where normal. The thing is though, when a drive goes bad, I don't think I can simply put in my spare drive and have it rebuild and I'll have to turn off the auto rebuild feature. Because, I wouldn't want one drive to be formatted correctly and the other not formatted correctly. I can't imagine the errors I would get. I'll have to run the Advanced Formatting Tool and then use the 'create an array from an existing array' feature of the Intel RAID software to rebuild my array.

I'm not new to RAID but I'm not a vet either. I have six years of real world experience with hardware and software. However, if I could do it again, I would not of purchased these drives for RAID array. I'm currently running two RAID5 and two RAID1 arrays in one server of mine and two RAID1 arrays on a second server of mine.

Oh, and you can still have a back up and not have it off site. It's still called a backup. That's going above and beyond the normal scope of things. The chances of you have a fire in your home is very very rare when compared to the failure rate of a hard drive.
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a c 415 G Storage
April 2, 2010 5:46:59 PM

thearm said:
Oh, and you can still have a back up and not have it off site. It's still called a backup. That's going above and beyond the normal scope of things. The chances of you have a fire in your home is very very rare when compared to the failure rate of a hard drive.


Fires are rare but burglaries aren't. If you keep all your backups in your home then make sure they're well hidden - external drives are a high-value and easily snatched target.
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April 8, 2010 1:53:48 AM

sminlal said:
Then what your asking for isn't backup - just as long as you're clear on that.

Although I'm a little confused as to why you'd be concerned with drive failure if you're not concerned about all those other risks. I've personally never had a drive failure, but I have had to restore data from backups for other reasons. I mean no malice when I say that someone who thinks all those other risks won't happen to him is very naive.



So I stumbled across this thread looking up info on TLER and the RS line of Western Digital Drivers and your ignorant assertions and hostile attitude compelled me to respond.

Offline backups are part of a proper backup solution but like RAID they are not a complete solution. In other words, with either solution you're exposed to data loss and by themselves, offline backups and RAID only mitigate potential damage under certain situations.

The primary purpose of RAID 1 is redundancy, in other words a fail-safe or live back-up usually implemented in situations where redundancy is imperative but cost out weights performance. RAID 1 offers the cheapest means for data protection and fault tolerance in a system however it leaves you vulnerable in the event of disasters that render the entire system inoperable.

Offline backup solutions can protected you from some disasters but unless they're off-site then their effectiveness is greatly reduced. Even if you have off-site backups, you're still vulnerable to latent data corrupt from the source and on the archive media and in the case of home users without multiple media sets to rotate out, the protection offered from this solution is almost none. Offline backup systems offer no redundancy and are only as good as the last backup, on other words you loose everything since the last backup in the event of a failure. As we know, hard drives are prone to shock related failures so the need to constantly transport off-site media sets back and forth only increases the likelihood of failure.

Mac and Windows operating systems do not actively notify or report hard drive errors. In OS X you have to monitor the SMART status in the Disk Utility and under Windows you have to sift through the System Event Log. Given that, if your primary or backup drive has problems you won't know about it. Nothing hurts more than diligently backing up a system only to find the backup media silently failed and you have no recovery options.

Given the likelihood of your house burning down vs a hard drive failing, I would go with RAID 1 over offline backups any day. According to Google's 2007 report on failure trends (http://static.googleusercontent.com/external_content/un...), drive failure rates were anywhere from 2-5% with 36% of those failing never reporting SMART errors. In that same year the American Housing Survey (http://www.census.gov/prod/2008pubs/h150-07.pdf) reported 110,692,000 regularly occupied homes and 414,000 home fires or a .374% failure rate.
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April 8, 2010 2:00:11 AM

RAID 1 array is an easy and effective data protection option and much less prone to user error than offline backups. Better still is enabling Volume Shadow Copy in Windows or Time Machine in OS X and having those archives stored on a Windows Home Server or Time Machine that implements RAID 1.
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a c 415 G Storage
April 8, 2010 3:03:24 AM

> So I stumbled across this thread ... and your ignorant assertions and hostile attitude compelled me to respond.

I don't mean to be hostile. But on this forum I see thread after thread where people are asking about RAID with apparently no thought having been given to backup. A lot of people seem to think that redundant RAID eliminates the need for backup. It doesn't. If you're going to spend money on extra drives then IMHO you need to use them for backups first, before thinking about RAID, because backups can protect your data from everything that RAID does and then some. In fact, it can protect against virtually all other risks.

I'm not saying that you shouldn't use RAID, I'm just saying that your priorities are misplaced if you're thinking about RAID without having implemented a sound backup strategy.


> The primary purpose of RAID 1 is redundancy, in other words a fail-safe or live back-up usually implemented in situations where redundancy is imperative but cost out weights performance.

I managed a data center many years and we found that the most useful benefit of redundant RAID was in the elimination of downtime due to drive failure. Without it, if a drive fails then you're down for the time it takes to replace the drive, restore the latest backup, and re-enter the transactions that occurred since the latest backup. That costs a business big bucks.

It never stopped us from doing backups, and in fact we had to perform restores on the behalf of negligent users and errant programs more often than we had to replace dead drives. And with hundreds of drives to deal with, that's saying something.

But from what I've seen for most of the people on this forum asking questions about RAID, downtime is less of an issue than the preservation of data. I don't know how many posts I've seen where people are desperate to get back data that they've lost, with or without RAID. A sound backup strategy would have saved pretty much all of them. That's where I'm coming from - trying to help people avoid that kind of grief.


Offline backup solutions can protected you from some disasters but unless they're off-site then their effectiveness is greatly reduced.

...as I suggested in the 2nd post of this thread. And with a modicum of care drives are more robust than you seem to think - since I switched from tape backups I've been schlepping the same set of external drives back and forth to my offsite location for over 6 years now and they're showing no signs of stress.


> Offline backup systems offer no redundancy and are only as good as the last backup...

Having multiple backup sets reduces the risk (as I also suggested in the 2nd post). And I can tell you that some of the folks who have posted here would be overjoyed even if they could recover to a backup taken last month.

But a strategy of incremental and full backups performed on rotating daily, weekly and monthly cycles and give you very complete coverage that allows you to not only recover all but the current day's work, but can also recover from undiscovered data corruption that occurred quite a while ago, depending on how much capacity you have on the media in your backup pool.


Given the likelihood of your house burning down vs a hard drive failing, I would go with RAID 1 over offline backups any day.

...then I truly believe your data is at greater risk than it should to be. Surely you don't think that a fire is the only other risk to your data! As I said above, burglaries are a lot more common than fires, and there are plenty of other risks to your data that RAID is powerless against (such as the data corruption that you yourself mentioned).

I'm not trying to be arrogant, but if your data is precious then I truly believe that your strategy is short-sighted.
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a c 415 G Storage
April 8, 2010 3:12:16 AM

> RAID 1 array is an easy and effective data protection option and much less prone to user error than offline backups.

And totally useless when somebody accidentally deletes a file.


> Better still is enabling Volume Shadow Copy in Windows or Time Machine in OS X and having those archives stored on a Windows Home Server or Time Machine that implements RAID 1.

i.e., "you should do backups". And if you're smart you'll squirrel the server away someplace so that it's less likely to be stolen along with your primary system, and connect it to a power-isolated UPS so that it doesn't get zapped by the same power surge that takes out the primary system.

The key point is that if you value your data you should make backups whether you use RAID or not.
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a c 342 G Storage
April 8, 2010 4:17:10 AM

I agree with sminlal. The huge advantage of RAID1 is immediate continued operation when a disk fails, keeping your computer running until some more convenient time to fix it properly. But I also recognize that a poorly-managed backup system provides much less security than a good one. For example, having only one backup drive unit and simply wiping it out and writing a new backup set to it does pretty much eliminate any ability to recover a file that has been corrupt for a month and nobody knew!

The core thing here is that people need to read up on these things and understand how they operate and why they should be used in particular ways. Too many people in these forums have "heard" that RAID1 gives you automatic backups. And too many who try to use backups do it badly and fail to achieve the protection they seek.

I have two scary stories. In one from many years ago on a "mainframe" machine, the attempt to restore from backup tapes failed because the tapes had been written incorrectly by the backup system - it had a programming "glitch". AND no operator had ever tried to VERIFY the backup tapes when they were written! In fact, the system had been deployed in many datacenters for many months, and nobody had reported the problem!

The other just proves no system can be completely guaranteed. One company in a World Trade Center tower did it all right, including storing their backups in a separate location - in the OTHER World Trade Center tower!

Oh, and one good news story. In one company where I worked the professionally-managed data center had a RAID5 array drive failure. Before they could replace it and rebuild the data, a second drive unit failed also, so the RAID5 system could not do its own rebuild. They had backup tapes stored locally AND on a remote website server, so the restoration got done - it just took about 3 LOOONNGGG days for IT staff while the business just kept running.
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April 8, 2010 8:40:56 AM

sminlal said:
...A lot of people seem to think that redundant RAID eliminates the need for backup.


That was never my assertion.


sminlal said:
..If you're going to spend money on extra drives then IMHO you need to use them for backups first, before thinking about RAID, because backups can protect your data from everything that RAID does and then some. In fact, it can protect against virtually all other risks.


No it doesn't actually. RAID and offline backups overlap in coverage however most backup software performs no consistency or integrity checks on the data being backed up, only on the backup itself so any corruption of your data can creep into your backups very easily.


sminlal said:
I'm not saying that you shouldn't use RAID, I'm just saying that your priorities are misplaced if you're thinking about RAID without having implemented a sound backup strategy.


You seem to be implying that offline backups in and of themselves are a sound backup strategy but they are not. They need to be combined with integrity and consistency checks of the source data, something that is very often overlooked.


sminlal said:
I managed a data center many years and we found...


I don't disagree with any of that but the enterprise is not comparable to a home user's PC. Most enterprise backup solutions involve RAID solutions, revolving backup media sets, and regular consistency and integrity checks of servers.


sminlal said:
But from what I've seen for most of the people on this forum asking questions about RAID, downtime is less of an issue than the preservation of data. I don't know how many posts I've seen where people are desperate to get back data that they've lost, with or without RAID. A sound backup strategy would have saved pretty much all of them. That's where I'm coming from - trying to help people avoid that kind of grief.


Offline backups alone are not a sound backup strategy and assuming that they are is just as bad as assuming RAID will always save the day.

sminlal said:
Having multiple backup sets reduces the risk (as I also suggested in the 2nd post). And I can tell you that some of the folks who have posted here would be overjoyed even if they could recover to a backup taken last month.

But a strategy of incremental and full backups performed on rotating daily, weekly and monthly cycles and give you very complete coverage that allows you to not only recover all but the current day's work, but can also recover from undiscovered data corruption that occurred quite a while ago, depending on how much capacity you have on the media in your backup pool.


Of course but that backup strategy is a bit unrealistic for your average user. Even in most businesses this process fails quite often despite the fact that someone is actually paid to maintain it. Do you honestly expect the average user to maintain this strategy?


sminlal said:
...then I truly believe your data is at greater risk than it should to be. Surely you don't think that a fire is the only other risk to your data! As I said above, burglaries are a lot more common than fires


I personally think that the risk to corruption of data is far more likely than a robbery, flood, fire or other disaster taking out your data and the numbers seem to support it. According to FBI unified crime reports, the burglary rates since the 60s have been less than 2% and in recent years less than 1%. Federal Census data on Fire and flood statistics indicate that your risk is less than .5%. Google's hard drive study, the most extensive ever performed, indicates that drive failure raters are higher than those other rates combined. Frankly those rates are inflated since they assume total loss but fires and floods often do not always result in total loss of property and burglaries do not always result in a stolen PC.


sminlal said:
there are plenty of other risks to your data that RAID is powerless against (such as the data corruption that you yourself mentioned).


There are many different types of data corruption, RAID can introduce many more however I was referring to latent data corruption which is one that RAID happens to virtually eliminate by introducing recovery from checksum mismatches.

NetApp put out a study about data corruption on disks that showed that latent data corruption was an order of magnitude greater than all other forms of corruption. They also identified that nearline storage like consumer SATA drives are considerably less reliable than enterprise storage like fiber channel.
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April 8, 2010 8:45:16 AM

I'm not saying RAID is complete backup solution but if you think offline backups are or that they protect you from everything that RAID covers then you're sorely mistaken. Ideally RAID and offline backups of some form should be used in conjunction with consistency and integrity checks to effectively protect your data however your average user isn't going to do this. They're going to run the software that comes with their external hard drive or use the backup utility that ships with the OS and assume that everything is fine while there is still considerable exposure to data loss.

With the usage pattern of an average user being to storage large data sets that are accessed infrequently if at all, maintaining the integrity of the data is paramount. Incremental, Differential and Continuous backups do not maintain the integrity of the data in anyway and Full backups just make sure a copy of the data in whatever state it is in is maintained. Because most operating systems do no alert the end user to sector failures on hard drives, data loss is very likely to go unnoticed to users long enough for it to spread into their backup media.

If sectors on your hard drive holding your mp3s, photos or movies start going bad are you going to notice? Hard drives automatically relocate data and flag sectors as bad when they have difficulty reading the data so frequently accessed data will unlikely be lost but most of the data people store isn't accessed frequently at all and so by the time you come around to accessing it, it may already be lost. Taking a backup of this bad data isn't going to help because the average user's operating system or backup software doesn't alert you to these types of failures or halt backup operations. In these situations your data would be lost completely.

I recently upgraded my home server's RAID 1 array from 300GB to 1TB drives. For various reasons I decided to do this by breaking the mirror and replacing one of the drives with a new 1TB drive. The resyncing process was progressing but it was taking too long which raised concerns so I checked the system log and saw a stream of read errors, sectors flagged as bad and data loss indicators. Going back through the logs it showed that the only other time the errors cropped up was during full backups where the entire disk was read. They weren't in incrementals because the data on the corrupt portion of the disk never changed. I halted the resync and swapped the 300GB disks out and restarted the resync process. It completed relatively quickly and afterward I compared the data on the new drive array to the bad disk and my last offline backup. The data matched the backup but 30% of what was on the bad disk differed from the backup and was unrecoverable. Had I not had a RAID solution in place then this corruption would have made it to my backups because it was never reported.

For your typical user a RAID 1 array is going to offer a great deal of protection and redundancy with a minimum of effort to setup and maintain on their part. Combined with something like Volume Shadow Copy or Time Machine, they have a very effective recovery solution from failure, corruption or accidental loss.
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a c 415 G Storage
April 8, 2010 10:02:55 AM

I could write a lengthy reply here (by which I mean one even longer than this!) but I suspect that to some degree we're arguing at cross purposes.

I have a hunch that you favour RAID because you're more concerned about recovery from short-term problems. For example, the idea of loosing a day's or a week's worth of data due to having to restore from a backup seems abhorrent to you.

I favour backup because I'm more concerned about long-term data security. I have literally 40 years' worth of data - if I have to re-create the last day's or week's worth it's a bit of short-term pain, but nothing compared to loosing precious files that are irreplaceable.

The thing with long-term data security is that over the years those 1% and 2% risks start to add up. Sure, you're not very likely to be burgled this year, but I *have* been burgled and over the last 40 years so have nearly half the people I know (and please don't get fixated on burglary - it's just one example out of many that RAID is powerless to protect against).

The most plaintive cries I see here are from those who have lost many year's worth of important memories. They'd do anything to get them back, but it's too late. In almost all those cases a backup would have saved them, but in many cases RAID wouldn't have. That's where I'm coming from.

Backup doesn't have to be hard to set up. Windows 7 includes a decent backup utility which performs versioning and automatically schedules runs. Attaching one of a pair of external drives overnight while the backup runs isn't rocket science. Even offsite backup is pretty trivial - a lot of people can just keep their latest backup at work.

I'm sorry, but I'm afraid you're just not going to convince me that on a long-term basis my data is safer on redundant RAID than on external, offline backups.
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