External Hard Drives

[Richb2004v2]

I bought an external hard drive a few months ago and now have everything on it. I don't really bother saving stuff on my machines unless I particularly need to. I am wondering if people ever have problems with them in terms of them going down. Obviously if it did I would be very inconvenienced.

[sbk]

Depends on the hard drive.... what brand are you using? Some are more reliable than others.

[KhunDave]

I've had a Western Digital Passport 250Gb for about a year. Used pretty much every day. No problems so far.

[webfact]

Depends on the hard drive.... what brand are you using? Some are more reliable than others.

EVERY HDD can fail! Even the most expensive... I trust the 'can never fail HDD' does not exist in this world.

I know some guys they back up the backup to another drive. Yes, it (can) also depend on the brand

I use 2 Maxtor 750GB USB drives for backup. No problems so far.

[sbk]

Well, yes, obviously anything can fail, hard drive, modem, computer, car, whatever. But, some drives are notorious for failure and are best avoided.

[angiud]

Western Digital have a higher grade of failure.

[monty]

Which is one of the reasons they have developed the different RAID systems.

If you have a very high need of not losing your data, there are external enclosures allowing RAID.

Most likely will be raid1 where there are 2 drives inside which will always be mirrored. Total capacity is the same as the smallest drive, loss of any of the drives will not lose any of your data.

Advantage, at all times, data on both discs are synchronized. So basically you always have a 100% up to date back up.

Disadvantage, expensive. The external cases offering this are more expensive and obviously you need to pay for two hard disks while having the capacity of only one.

Practically, I would put a RAID 1 in my PC. Most modern mainboards support RAID, so for the price of 1 extra drive you have almost 100% peace of mind, without having to bother about back ups etc...

Raid 5 is also a posibility, here you use 3 drives, you have the capacity of only 2 drives but still 100% of your data if one goes down. more cost effective as you only lose 33% of capacity as opposed to the 50% in RAID 1.

However, if 1 drive fails, you'll lose a lot of speed until you replace the broken drive and let the system rebuild the data. Which can take a long time if you have a lot of data on there!

[nikster]

If you are looking for a cheap 2.5" external - advantage is it's powered over USB so it doesn't die on power cuts and there are a lot fewer cables- go for one of the brand name all-in-ones. WD is easiest to get in thailand but I have also seen Buffalo and Toshiba.

Anyway, that's what I use. I would not really trust a RAID 1 - it protects you against a HD failure, but not against data corruption, a virus, a fire, a stolen laptop (OK unlikely for a desktop )...

I have to say I love OS X TimeMachine, it's really an amazing backup solution. It's so fast and easy to recover things, and to find stuff...

[monty]

Anyway, that's what I use. I would not really trust a RAID 1 - it protects you against a HD failure, but not against data corruption, a virus, a fire, a stolen laptop (OK unlikely for a desktop wink.gif )...

Very true, however the OP inquired on HD failure rates/risks, against which RAID 1 protects perfectly fine

[namoo]

HP Mediasmart Server with 4 x 2TB drives and file duplication so every file on it is also duplicated on one of the other 3 drives.

Really great product and works with Time Machine also.

I guess I am paranoid as have a Time Capsule running alongside the above....

[Johnxxx]

I bought an external hard drive a few months ago and now have everything on it. I don't really bother saving stuff on my machines unless I particularly need to. I am wondering if people ever have problems with them in terms of them going down. Obviously if it did I would be very inconvenienced.

I have 4 external HDs and no problem. Just normal HDs BUT in a metal box with fan!!! Of course not the 2 notebook drives.

One thing I encountered and just found out by accident. The interface of one box had a problem. So it created sometimes a writing error without ANY error message. The file was not damaged so could be read - but was not the same anymore. This happened mostly with very big files. Since that time I check every new interface with Total Copy (free) where you can check if the write was correct.

[hhgz]

"Which is one of the reasons they have developed the different RAID systems."

A properly configured RAID system will save 100% of your data, and have a failure rate (that would be when you lost data) of one per several hundred million operating hours.

[Johnxxx]

"Which is one of the reasons they have developed the different RAID systems."

A properly configured RAID system will save 100% of your data, and have a failure rate (that would be when you lost data) of one per several hundred million operating hours.

You are right - but this Raid does not protect against any virus - or ???

[monty]

"Which is one of the reasons they have developed the different RAID systems."

A properly configured RAID system will save 100% of your data, and have a failure rate (that would be when you lost data) of one per several hundred million operating hours.

You are right - but this Raid does not protect against any virus - or ???

No it doesn't.

It just protects data. It's not a back up per se, it's just that all your data is always simultaneously written onto two different drives.

Then again, do a normal backup onto an external drive at the wrong time, and you'll be backing your virus infection as well...

[Johnxxx]

"Which is one of the reasons they have developed the different RAID systems."

A properly configured RAID system will save 100% of your data, and have a failure rate (that would be when you lost data) of one per several hundred million operating hours.

You are right - but this Raid does not protect against any virus - or ???

No it doesn't.

It just protects data. It's not a back up per se, it's just that all your data is always simultaneously written onto two different drives.

Then again, do a normal backup onto an external drive at the wrong time, and you'll be backing your virus infection as well...

My next computer should have Raid 0 - so use 2 drives at the same time. Do you have any expierence with the performance increase with Raid 0 ?

[Crushdepth]

I found raid 0 significantly faster (at least for read, not sure about write) but at the expense of reliability. You are at least doubling your chances of disk failure, and sudden power cuts will often break the raid if your UPS fails or you don't have one.

You *need* a separate physical backup if you are going to use RAID 0. External hard drive and a bit of "backup discipline" should see you right.

[Richb2004v2]

I have a seagate freeagent. I guess that as one poster says anything can break.

[jfchandler]

I think the key considerations are keeping more than one backup (preferably two or more duplicates) and keeping them on physically separate drives, with one preferably off-site.

My approach:

1. I keep my data files on a separate logical drive/partition on my C: drive, which thus becomes a D: drive. That way, I can install and reinstall Windows, and pretty much not have to worry about affecting my data, even if I have to wipe my C: drive.

2. I keep a separate USB external drive attached to my PC that mirrors all my data files on my D: drive, using Microsoft SyncToy.

3. I pay and subscribe for an online backup service, in my case Mozy, which is configured to automatically throughout the day and night backup my data files to their remote server via my Internet connection.

That way, if my main hard drive fails, I'm OK.

If my external hard drive fails, I'm OK

If my house burns down or floods or my PC is stolen, I'm OK.

Of course, if I die, I don't have any backup for that...

[think_too_mut]

Practically, I would put a RAID 1 in my PC. Most modern mainboards support RAID, so for the price of 1 extra drive you have almost 100% peace of mind, without having to bother about back ups etc...

Normal home PC would choke without SCSI controller that uses different channels to access different disks.

Raid 5 is also a posibility, here you use 3 drives, you have the capacity of only 2 drives but still 100% of your data if one goes down. more cost effective as you only lose 33% of capacity as opposed to the 50% in RAID 1.

However, if 1 drive fails, you'll lose a lot of speed until you replace the broken drive and let the system rebuild the data. Which can take a long time if you have a lot of data on there!

I still have to see RAID-5 with number of disks different than 4. Gain over RAID-1 is 25% (space worth 1 drive is lost to parity) but performance is inferior far more than that.

Real heavy duty places use external RAID-1 for production and external RAID-5 for development and testing.

[monty]

Normal home PC would choke without SCSI controller that uses different channels to access different disks.

IMO not true, not since the faster SATA standard has been used.

Several PC magazines/websites have tested on mid class motherboards, and none found any performance hit using raid1 versus a simple single drive.

Raid 0 obviously is a fair bit faster, but a bit risky, as when 1 drive has an error, you loose the lot...

[think_too_mut]

.... however the OP inquired on HD failure rates/risks, against which RAID 1 protects perfectly fine

High end drives (4,000US$ a piece) fail at 0.17% to 0.22% rate a year. Large places, like American Express for example, would have tens of thousans of them. Replacing 2 disks per 1,000 installed a year due to h/w failure is acceptable.

[think_too_mut]

Normal home PC would choke without SCSI controller that uses different channels to access different disks.

IMO not true, not since the faster SATA standard has been used.

Several PC magazines/websites have tested on mid class motherboards, and none found any performance hit using raid1 versus a simple single drive.

Raid 0 obviously is a fair bit faster, but a bit risky, as when 1 drive has an error, you loose the lot...

You could be right albeit for the wrong reason. In a hobby environment it is usually sufficient unless you are a CAD designer who works with large files.

Where is the parity calculated?

1. The cheapest is - software based. Windows or other OS would have that.

PC Magazines did not see any performance degradation (with disks) because of that - the parity calculation time is consumed at the OS level so the disks will get the data already chewed and all the same to them. PC Magazines most likely don't realize that. Possibly, they don't have to bother.

2. Hardware calculated - at HBA (the card that links the server with the external storage). OS does not do any calculation.

3. External array calculates parity, OS and HBA have no idea what is happening, just send the data through the shute. External disks have a special firmware (their own OS) that recognizes that and they do the work.

Raid 0 is for performance (striping the data across multiple disks, no parity, no protection) .

[sbk]

CNET just had an article on this: forums.cnet.com/5208-7588_102-0.html?messageID=3048455&tag=nl.e400

[CosmicSurfer]

The HDD is not the only thing you need to worry about in an External situation....

I almost lost all my Data when the BOX went bad during a power failure/surge.... (Pre UPS... now I have 2)

The HDD was fine, but the bad box/case caused lots of damage.. after revovery (about 60-70% of my data) I bought a new box, and the drive worked fine again.

That was on my old laptop with external.

Now in my new Desktop setup, I have 4x Internal (O/S, Apps, 2x data), plus an e-Sata external RAID 1 doing Data & Settings Back-Ups, plus the periopdic Image..., Plus a Firewire external single box holding data that I don't need to access frequently, and a USB external (Which I only turn on for High Priority back-ups)... All Boxes are Aluminum, but only the Double RAID Box also has a fan. (The Raid Box is also Hot-Swappable) My mistake was only buying a box for 2 drives.. should have bought a 4-drive box... But EXPENSIVE.

Now, as I'm using all Internal Sata ports, I'm thinking of adding a new Sata card so I can add another Internal (I have a drive hanging around doing nothing and room for another 2 drives in my Desktop, but no ports.), and then I'll have an extra e-Sata external port if I need it in the future .. I have a BIG box with 7 fans for cooling.

Never too much memory... and can never be too careful about backups....

CS

[monty]

Normal home PC would choke without SCSI controller that uses different channels to access different disks.

IMO not true, not since the faster SATA standard has been used.

Several PC magazines/websites have tested on mid class motherboards, and none found any performance hit using raid1 versus a simple single drive.

Raid 0 obviously is a fair bit faster, but a bit risky, as when 1 drive has an error, you loose the lot...

You could be right albeit for the wrong reason. In a hobby environment it is usually sufficient unless you are a CAD designer who works with large files.

Where is the parity calculated?

1. The cheapest is - software based. Windows or other OS would have that.

PC Magazines did not see any performance degradation (with disks) because of that - the parity calculation time is consumed at the OS level so the disks will get the data already chewed and all the same to them. PC Magazines most likely don't realize that. Possibly, they don't have to bother.

2. Hardware calculated - at HBA (the card that links the server with the external storage). OS does not do any calculation.

3. External array calculates parity, OS and HBA have no idea what is happening, just send the data through the shute. External disks have a special firmware (their own OS) that recognizes that and they do the work.

Raid 0 is for performance (striping the data across multiple disks, no parity, no protection) .

There is no parity calculation in raid 1. Exactly the same is written on two disks, called mirroring.

Raid 5 uses striping with parity, which needs calculation done.

[think_too_mut]

There is no parity calculation in raid 1. Exactly the same is written on two disks, called mirroring.

Oh, is it what it is called?

Like you put a mirror in front of your face and it is there, no effort?

There is more to it that also requires processing time.

To write a block of data (usually 32KB) to 2 disks, something has to:

Queue the block for writing.

Then send it to one disk.

The disk sends acknowledgement.

Then the block is sent to the second disk.

The second disk sends acknowledgement.

The block in cache is then marked as reusable space for another i/o operation.

Just for fun, something else may require a block of data to come back from the disk (mirrored disks are seen as 1 disk).

While above is in progress, something has to get that data from the mirrored pair. It will take it from the disk currently idle. Something has to control all that.

For even more fun, current write and read operation from the mirrored pair of disks gets another write request. It will go to the currently idle disk (say, one that is just supplying data to read operation) and data gets written to it, waiting on previous write operation to complete before sending it to the first disk.

For microseconds, your mirrors are different. And that happens all day long, for the life of the mirrored pair.

That is where external storage arrays differ in capabilities and price - how they ensure "user view" is exactly what naive assumtion they are mirrors, like you standing in front of one in your bathroom.

Your bank accounts, airline reservations, air traffic control, much of real life things, live like that.

[britmaveric]

Dumb question since you save everything on the usb hard - do you have a backup of it? If not you need to do so or risk losing everything.