Using Raid 0 + Time Machine

[dhrlee]

Hello all, I am new to this forum.

I have early 2008 mac pro and recently purchased 2x 640GB HDD to make a raid 0 for my boot disk. My question is if I use time machine to backup raid 0 disks, would I be able to full restore HDD if one of raid 0 HDDs fails? I heard some horrible stories and I just want to make sure I can somehow restore my data if one of the drives fail. I am also thinking of doing this on a single 1.5TB disk. Would this work?

If not, could I setup raid 1 using a single drive, which is 1.5TB, to 2x raid 0 drives (640GB x2)?

 

[Badger^2]

do you need the kind of backup TM offers?

A minute by minute backup?

Or would you rather have a bootable backup?

In that case, Carbon Copy Cloner or SuperDuper would be a better choice for backup.

Regardless if you have a RAID 0 or not.

I personally have never been a fan of RAID 0. 2 drives = 2x the rate of failure.

What are you doing that makes you really want a RAID 0?

 

[dhrlee]

I just need a backup in case of HDD fail

I have been using TM since the day 1 I bought mac pro back in early 2008, but never used it once. So I guess I would be more interested in a monthly backup than minute by minute backup. I opted out for TM since its part of OSX feature. I just wanna have a backup in case of HDD failure.

I just never used raid 0 before and I thought it could boost some performance in general. My computer runs very slow when I launch apps, especially with VMs running. I have plenty of RAM (10GB) and CPU (8x 2.8ghz), so the only thing that slowing down the system is HDD I thought. I look at system monitor and almost every time its slow because of data read and write. Is this bad decision?

 

[KG2002]

I personally have never been a fan of RAID 0. 2 drives = 2x the rate of failure.

What are you doing that makes you really want a RAID 0?

It depends. I was also concerned but went with RAID 0 for the sake of performance.

Think about the risk for a minute. The risk we are all concerned about is not a drive failure but a data loss. With a full TM backup (or any other backup tool) the risk is well mitigated, don't you think?

If you worry about disk failure as a physical drive failure (meaning lost $$$ to replace the HDD), with RAID 0 the risk does not change much.

 

[lemonade-maker]

It depends. I was also concerned but went with RAID 0 for the sake of performance.

Think about the risk for a minute. The risk we are all concerned about is not a drive failure but a data loss. With a full TM backup (or any other backup tool) the risk is well mitigated, don't you think?

If you worry about disk failure as a physical drive failure (meaning lost $$$ to replace the HDD), with RAID 0 the risk does not change much.

You are right. Raid 0 is ideal with proper backup. Timemachine and clone does just that. Drives are cheap.

 

[dhrlee]

So lets say..

You are right. Raid 0 is ideal with proper backup. Timemachine and clone does just that. Drives are cheap.

So let's say I backed up with TM. If one drive fails in raid 0 and I can't no longer boot from raid 0 drive, how do I restore my raid 0 boot drive setup?? Can I just boot from DVD and restore?

 

[lemonade-maker]

So let's say I backed up with TM. If one drive fails in raid 0 and I can't no longer boot from raid 0 drive, how do I restore my raid 0 boot drive setup?? Can I just boot from DVD and restore?

You have options. My system is cloned every night with carbon copy cloner and timemachine is set to do it's thing every four hours. I would boot the clone then recreate the raid and restore from the clone. Then restore missed files from timemachine if needed. Your idea of boot from DVD and restore from timemachine works too. Takes a little longer.

I get read/writes in the 400-450 MB/s range using 4x1.5tb disks

 

[justit]

I've got the same set-up:
2x 640GB Black Caviars as RAID0, and a 1.5TB Green and that Apple stock 350GB as a slap-it-in clone stored outside.

I've placed all data, all user folders, media like iTunes library, onto the 1.5TB to separate OS from data and keep the RAID0 at no more than 5% capacity for optimal performance.

Using time machine for constant incremental backing up for just the OS boot and apps is complete overkill and degrades your experience/speed during the day. All you need is a recent clone on either your 1.5TB or an external HD to boot from in case your RAID0 fails. Installed a new app lately? Then create that new clone.

To understand RAID drive failure, you have to take into account usage.
Desktop use– using your MP during the day as a single user, is different than server use– multiple hard drive requests occurring 24 hours a day, with very little idle time. Servers should always be run as a RAID5 or RAID10.

Use TM to run backups of your data– that which changes constantly. Keep data separate from OS/Apps.

 

[lemonade-maker]

One persons overkill is anothers piece of mind. TimeMachine only backs changed files. No real reason to separate your data except to have a more complex system. Drives are cheap, the content you create is not. If your data and system have any value at all, you can't have enough backups - including the OS.

 

[justit]

No real reason to separate your data except to have a more complex system.

Just one, performance in boot RAID0

 

[lemonade-maker]

Just one, performance in boot RAID0

If you are saying it boots faster, it's really not important. If you are saying it's faster after boot to keep your data separate, it's marginal.

 

[justit]

If you are saying it boots faster, it's really not important. If you are saying it's faster after boot to keep your data separate, it's marginal.

Read/Write speeds are important to us RAID (and soon to be SSD) enthusiasts. No worries if that's not what you're into.

 

[madwolf]

I've got the same set-up:
2x 640GB Black Caviars as RAID0 (...)

I've placed all data, all user folders, media like iTunes library, onto the 1.5TB to separate OS from data and keep the RAID0 at no more than 5% capacity for optimal performance.
(...)

You use no more than 5% of capacity of those caviars? That would be 64GBs. For the price of 2 Caviar Blacks you would get a very nice 64GB SSD, wouldn't that be much better for system disk (lots of small files) thanks to 100x faster access times?

 

[justit]

You use no more than 5% of capacity of those caviars? That would be 64GBs. For the price of 2 Caviar Blacks you would get a very nice 64GB SSD, wouldn't that be much better for system disk (lots of small files) thanks to 100x faster access times?

Active project files I place on the RAID0. My point was to illustrate that there are different backup types for different drive uses. But, I'm discovering that my VMs are slower on the green caviar and I may have to put them on the RAID0 as well. The space that I have to experiment is just not there using SSD pricing.

 

[nanofrog]

You are right. Raid 0 is ideal with proper backup. Timemachine and clone does just that. Drives are cheap.

It depends on what the system is needed for. A stripe set is fine, if you have the time to fix it when it fails. Otherwise, another array type would be better suited, as each system's priority list isn't the same.

Always the usage pattern...

But no matter the array type used, or if it's a single disk, you need a proper backup.

But, I'm discovering that my VMs are slower on the green caviar and I may have to put them on the RAID0 as well.

How much memory is installed in the system, and how is it allocated?

 

[justit]

How much memory is installed in the system, and how is it allocated?

MP has 8G, The VMs itself either 1 or 2Gbs keeping it as low as possible, but since I use restore instead of restarting the VMs, it's more a Fusion issue running better on the RAID0.

 

[Tesselator]

My question is if I use time machine to backup raid 0 disks, would I be able to full restore HDD if one of raid 0 HDDs fails?

Yes.

I am also thinking of doing this on a single 1.5TB disk. Would this work?

Yes.

I guess I would be more interested in a monthly backup than minute by minute backup.

Monthly is not often enough unless you only use your mac 2 hours a week.

I opted out for TM since its part of OSX feature. I just wanna have a backup in case of HDD failure.

I personally have not used TM but there's a very good poster/user here who does and he says he can restore the total system from a TM backup - and that it's safe and easy. I trust him so that's that for me.

I just never used raid 0 before and I thought it could boost some performance in general. My computer runs very slow when I launch apps, especially with VMs running. I have plenty of RAM (10GB) and CPU (8x 2.8ghz), so the only thing that slowing down the system is HDD I thought. I look at system monitor and almost every time its slow because of data read and write. Is this bad decision?

No. It's the best decision you can make. You just MUST keep a backup is all. And you should backup once a day or so. I guess you can set TM up like that.

So let's say I backed up with TM. If one drive fails in raid 0 and I can't no longer boot from raid 0 drive, how do I restore my raid 0 boot drive setup?? Can I just boot from DVD and restore?

Yes. Replace the failed drive, recreate the RAID0 and restore from TM.

 

[nanofrog]

MP has 8G, The VMs itself either 1 or 2Gbs keeping it as low as possible, but since I use restore instead of restarting the VMs, it's more a Fusion issue running better on the RAID0.

Worth a shot, as you already have the array.

 

[justit]

I personally have not used TM but there's a very good poster/user here who does and he says he can restore the total system from a TM backup - and that it's safe and easy. I trust him so that's that for me.

I'd like to read that thread. Not sure how TM works at restoring the OS on a new drive. Wouldn't one have to install OS and then recover from backup TM restore?

From a clone you can copy and recover to a new drive in a few minutes.

 

[Tesselator]

I'd like to read that thread. Not sure how TM works at restoring the OS on a new drive. Wouldn't one have to install OS and then recover from backup TM restore?

From a clone you can copy and recover to a new drive in a few minutes.

A few minutes? I guess if the drive were small enough you could.

But if you'd like to search for the post/thread in question the user's name is bozz2006.

 

[nanofrog]

A few minutes? I guess if the drive were small enough you could.

But if you'd like to search for the post/thread in question the user's name is bozz2006.

You can if there's not much on the drive. Even a 2TB disk can be cloned in a couple of minutes if the data is say under 10GB total (OS, apps and data). Full backup too.

But even 100GB will take ~17 - 20 min to run on a mechanical drive capable of sustaining 100MB/s. Not a speedy demon at all.

 

[Tesselator]

You can if there's not much on the drive. Even a 2TB disk can be cloned in a couple of minutes if the data is say under 10GB total (OS, apps and data). Full backup too.

But even 100GB will take ~17 - 20 min to run on a mechanical drive capable of sustaining 100MB/s. Not a speedy demon at all.

For Mac that actually sounds very fast. I've "copied" a terabyte or two by drag & drop probably 5 times in the past 6 months and each time I get an average of about 45 MB/s. Doing so from one 3-drive RAID0 to another 3 Drive RAID0 I can average almost 65 MB/s. So, 100 MB/s sounds great for full drive cloning!

 

[nanofrog]

For Mac that actually sounds very fast. I've "copied" a terabyte or two by drag & drop probably 5 times in the past 6 months and each time I get an average of about 45 MB/s. Doing so from one 3-drive RAID0 to another 3 Drive RAID0 I can average almost 65 MB/s. So, 100 MB/s sounds great for full drive cloning!

I haven't done it with a Mac (in OS X), and presumed the sofware was approximately the same as that on the PC side (I'm using TrueImage 2009 on the PC side). So I figured on a relatively recent drive make being capable of holding 100MB/s on the outer tracks.

I hadn't realized it's that slow under OS X, and the processors can certainly handle the application quick enough. There's plenty of bandwidth for a pair of drives in Mac systems as well.

 

[Tesselator]

I haven't done it with a Mac (in OS X), and presumed the sofware was approximately the same as that on the PC side (I'm using TrueImage 2009 on the PC side). So I figured on a relatively recent drive make being capable of holding 100MB/s on the outer tracks.

I hadn't realized it's that slow under OS X, and the processors can certainly handle the application quick enough. There's plenty of bandwidth for a pair of drives in Mac systems as well.

Yeah, I'm not sure why it's so slow. Asynchronous/synchronous I/O state, the extra time taken to build the tree structures for 600,000 "items", the hamsters are not being fed well enough and are weak, the types/sizes of files being copied? But just today 880 GB took very close to exactly 4 hours - which is like 62 MB/s. If I copy just a single 1 GB avi file it goes at about 160 MB/s though - if that's any clue. <shrug>

 

[nanofrog]

Yeah, I'm not sure why it's so slow. Asynchronous/synchronous I/O state, the extra time taken to build the tree structures for 600,000 "items", the hamsters are not being fed well enough and are weak, the types/sizes of files being copied? But just today 880 GB took very close to exactly 4 hours - which is like 62 MB/s. If I copy just a single 1 GB avi file it goes at about 160 MB/s though - if that's any clue. <shrug>

In a clone, it's 1:1 (no compression or calculations, as its a direct copy of the drive), and the only thing I can think of is random access of small files. If there's enough of them, it could get to the 60's MB/s range.

For TM or other backup software, the compression employed could slow you down as well.