Need advice on RAID1

S

Stuh505

Limp Gawd
Joined
Feb 15, 2004
Messages
488
I have been becoming increasingly conscious lately of my dependency on my hard drive. If anything were to fail the data would be irreplacable. This morning I woke up and was convinced that some files had disappeared...and decided it was time to get a raid system. It turns out that I had just misplaced the files, thank god, but the panic did it's job at getting the message through: it's worth it

I want a RAID1 system (mirror) for 200-400 GB. However this is one area in which I am pretty ignorant. I've been using the same 7200rpm 80GB WD HD for the last 5-6 years! I've been using a 120GB USB Seagate hard drive as well. It is nice having an external because it makes reformats simple...but it looks as though going external USB with a raid setup is going to be a lot less cost effective, so I was thinking I would just get a raid card + 2x hard drives.

My motherboard is a Abit KN8 (http://www.abit-usa.com/products/mb/products.php?categories=1&model=284) mobo.

I'm not sure about compatability, or the difficulties that I may encounter in setting this up, or what are good reliable brand names. I was thinking about getting these:

2x Seagate Barracuda 7200.9 ST3400833AS 400GB 7200 RPM 8MB Cache SATA 3.0Gb/s Hard Drive
(http://www.newegg.com/Product/Product.aspx?Item=N82E16822148246)

For the raid card, I just have NO idea what a good compatible deal is...there is such a large variation in price, suggestions welcome
 
Skip the RAID1 for backup as it's intended purpose is to maximize uptime, not protect files. I'd stick with an external backup drive solution and do incremental backups of important files.
 
Stuh505 said:
I have been becoming increasingly conscious lately of my dependency on my hard drive. If anything were to fail the data would be irreplaceable.
Click to expand...
Which ought to make you want to think about how you will back up that data. RAID is not backup.
 
drizzt81 said:
Which ought to make you want to think about how you will back up that data. RAID is not backup.
Click to expand...
So what is raid 1? If one disk goes, the other disk still holds all the data right? That sounds like backup to me, or better said, protection in the event that one of your two hdd fails. True backup is external hdd that are not connected to your system, but raid 1 seems to be the next best thing.

So what am I missing here?
 
RAID 1 is good enough for most data protection. This is IMHO, of course.
 
Juardis said:
So what is raid 1? If one disk goes, the other disk still holds all the data right? That sounds like backup to me, or better said, protection in the event that one of your two hdd fails. True backup is external hdd that are not connected to your system, but raid 1 seems to be the next best thing.

So what am I missing here?
Click to expand...

It only protects if one hard drive fails. The problem is that I have seen plenty of cases where another component failed (like a PSU) and took out both drives at the same time.

The problem with RAID1 is that everything is copied to both drives at the same time. Accidentally delete some files, they are gone off both. What happens if there is a fire or someone breaks in and steals your computer? Both drives are in the same computer hooked up to the same components and subject to everything the other drive is. The ONLY thing RAID1 protects against is if a single drive dies on its own. Any outside force that cause damage to 1 drive, will damage the other drive.
 
brom42 said:
It only protects if one hard drive fails. The problem is that I have seen plenty of cases where another component failed (like a PSU) and took out both drives at the same time.

The problem with RAID1 is that everything is copied to both drives at the same time. Accidentally delete some files, they are gone off both. What happens if there is a fire or someone breaks in and steals your computer? Both drives are in the same computer hooked up to the same components and subject to everything the other drive is. The ONLY thing RAID1 protects against is if a single drive dies on its own. Any outside force that cause damage to 1 drive, will damage the other drive.
Click to expand...
Ok, that's what I thought you were trying to say. I agree with that. But I've had one out of two disks go bad on me in the past, so raid 1 seems like a better alternative. But yes, for all my photographs and home vids, I have 2 external hdd to back up to. Can never be too safe with memories :)
 
Juardis said:
Ok, that's what I thought you were trying to say. I agree with that. But I've had one out of two disks go bad on me in the past, so raid 1 seems like a better alternative. But yes, for all my photographs and home vids, I have 2 external hdd to back up to. Can never be too safe with memories :)
Click to expand...

With the price of hard drives these days there isn't a good reason to not run RAID1. Note (see sig) that I run RAID1 configs in all my systems. Nothing farks up your day like a random hard crash. :(
 
I've decided to just make incremental backups...and I've decided that the most practical way to do this is just to buy internal HD's. I can't do tape, because it's too expensive. I checked out the 70mb SATA disks...but its like $70 for a 70GB disk, which is pretty stupid, because I can buy a 400 GB HD for $99. So thats what I'm going to do.
 
brom42 said:
With the price of hard drives these days there isn't a good reason to not run RAID1. Note (see sig) that I run RAID1 configs in all my systems. Nothing farks up your day like a random hard crash. :(
Click to expand...

I recently saw some benchmarks of onboard RAID controllers showing that RAID-1 degraded the access time when compared to a single drive.
If you are willing to lose that (bit of?) performance, then RAID-1 is certainly nice to have.
I run my mother's computer with RAID-1 across two old HDDs. I feel that this increases the durability of her PC, since I won't have to replace a failed HDD right away.

Stuh505 said:
I've decided to just make incremental backups...and I've decided that the most practical way to do this is just to buy internal HD's. I can't do tape, because it's too expensive. I checked out the 70mb SATA disks...but its like $70 for a 70GB disk, which is pretty stupid, because I can buy a 400 GB HD for $99. So thats what I'm going to do.
Click to expand...

Excellent plan. Make sure that you handle the disk(s) carefully. I'd also recommend to test your backup at least once, so that you know it works if you ever needed to restore it.
 
Juardis said:
So what is raid 1? If one disk goes, the other disk still holds all the data right? That sounds like backup to me, or better said, protection in the event that one of your two hdd fails. True backup is external hdd that are not connected to your system, but raid 1 seems to be the next best thing.

So what am I missing here?
Click to expand...

No it isn't a form of backup. RAID was designed to maximize uptime and create large volumes out of smaller drives. RAID is redundancy, not backup. The concepts are fundamentally different. Think about this: A RAID array does not protect you from viruses or spyware/malware. It also doesn't protect your data from corruption either. Any problems encountered on the primary drive are replicated instantly to the mirrored drive. Also consider that RAID doesn't protect you from power surges, fires or anything else that could happen to the physical machine.

RAID is fine when used properly and it can provide maximum uptime, and in some instances performance boosts. In no way has it ever been meant to be used as a form of backup. You need a good backup regiment in the event of fire, flooding or data corruption/viruses and more if your data is really that important to you. I use RAID heavily in all my systems and I've spent a great deal of money on RAID controllers and drives in the past. However, for data that is really important, I back the data up on DVD and place it in my safe. Some data that is important to me but isn't overly sensitive I've given to a friend to keep at their house as an offsite backup. RAID volumes also impose a performance hit to a small degree as well as increased risk of failure in the case of a RAID 0 volume. Additionally, your power requirements and hardware costs go up. Think very carefully before putting a RAID array in place on your machine.

I usually advocate a RAID 1 or RAID 5 array (or RAID 1+0) in conjunction with a solid backup plan for anyone who claims to have important data. There is simply no substitute for a real backup strategy.
 
drizzt81 said:
I recently saw some benchmarks of onboard RAID controllers showing that RAID-1 degraded the access time when compared to a single drive.
If you are willing to lose that (bit of?) performance, then RAID-1 is certainly nice to have.
I run my mother's computer with RAID-1 across two old HDDs. I feel that this increases the durability of her PC, since I won't have to replace a failed HDD right away.



Excellent plan. Make sure that you handle the disk(s) carefully. I'd also recommend to test your backup at least once, so that you know it works if you ever needed to restore it.
Click to expand...

True, but it really depends on the onboard RAID that you are using. Most of my older PCI based SI RAID controllers do degrade access time, but on my current system I increased both write and read times due to the performance bump from using write-back caching and some of the other added features.
 
drizzt81 said:
I recently saw some benchmarks of onboard RAID controllers showing that RAID-1 degraded the access time when compared to a single drive.
Click to expand...

If done well, read service times can decrease, and write service times increase a bit. Reads can be done faster, because the controller can seek whichever disk is closer. But the penalty is paid on writes; then both disks have to seek before the write is complete.

I haven't done the math on this, but for really read-heavy loads, it might be better to have the disks store the data with an offset:
Disk 1: ABCDEFGHIJK
Disk 2: FGHIJKABCDE
Then the average distance to a given block would be decreased, I think. I don't know of any controllers that do this, but it'd be interesting to implement it and see what it does. Choosing the offset (and the effect of more-than-two-way striping) would be an interesting problem.
 
brom42 said:
True, but it really depends on the onboard RAID that you are using. Most of my older PCI based SI RAID controllers do degrade access time, but on my current system I increased both write and read times due to the performance bump from using write-back caching and some of the other added features.
Click to expand...

Onboard RAID typically does well with RAID 0, but in other RAID modes I've noticed they tend to suffer a bit.
 
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