[Rant] Why is RAID creation so damn sucky?

[Loa]

Hello,

It took me an hour to create two RAID0s from two partitioned drives. An hour. WTF???

In theory the process takes 1 minute: create 4 partitions and bind them in 2 distinct RAID0. 1 minute at most.

Yet creating this tonight (and those few last times I've had to make them) took a lot more time. Disk Utility kept crashing about 1 attempt out of every 3; the process would halt at creating that damn POSIX resource busy about 3 out of 5 times; or DU would simply freeze once every 5 or 6 attempts; or the first RAID would fail just as I try to create the second about 1 out of 3 attempts; or DU would create volumes that were unmountable (but without any explanations) just about 1 out of 2 attempts.

WTF is wrong with this? Now I know most Mac users don't create RAIDs, but still. Damn!

I succeeded by doing exactly what I'd been trying to do. For some reason all those possible failures didn't happen on that last try. Feels like my Mac just turned into a Windows 3.0 machine...

Loa

 

[derbothaus]

You are having a special experience. 1 min tops for me.

 

[solaris8x86]

Mine just needs 4 seconds to create 2TB x 4 RAID-0.

 

[thedarkhorse]

RAID0 from drive partitions? Why?

 

[wonderspark]

I've never created RAIDs out of multi-partitioned drives, just single partition (whole) drives. Having said that, the only RAID creation that took a long time was RAID 5 with three 2TB drives; it took hours to complete. RAID 0 takes seconds with all else being exactly the same.

 

[flatfoot]

Hello,

It took me an hour to create two RAID0s from two partitioned drives. An hour. WTF???

In theory the process takes 1 minute: create 4 partitions and bind them in 2 distinct RAID0. 1 minute at most.

Yet creating this tonight (and those few last times I've had to make them) took a lot more time. Disk Utility kept crashing about 1 attempt out of every 3; the process would halt at creating that damn POSIX resource busy about 3 out of 5 times; or DU would simply freeze once every 5 or 6 attempts; or the first RAID would fail just as I try to create the second about 1 out of 3 attempts; or DU would create volumes that were unmountable (but without any explanations) just about 1 out of 2 attempts.

WTF is wrong with this? Now I know most Mac users don't create RAIDs, but still. Damn!

I succeeded by doing exactly what I'd been trying to do. For some reason all those possible failures didn't happen on that last try. Feels like my Mac just turned into a Windows 3.0 machine...

Loa

I'm feeling with you. Have had that experience, too, even with non-partitioned drives.

 

[GlynJones]

Hello,

It took me an hour to create two RAID0s from two partitioned drives. An hour. WTF???

In theory the process takes 1 minute: create 4 partitions and bind them in 2 distinct RAID0. 1 minute at most.

Yet creating this tonight (and those few last times I've had to make them) took a lot more time. Disk Utility kept crashing about 1 attempt out of every 3; the process would halt at creating that damn POSIX resource busy about 3 out of 5 times; or DU would simply freeze once every 5 or 6 attempts; or the first RAID would fail just as I try to create the second about 1 out of 3 attempts; or DU would create volumes that were unmountable (but without any explanations) just about 1 out of 2 attempts.

WTF is wrong with this? Now I know most Mac users don't create RAIDs, but still. Damn!

I succeeded by doing exactly what I'd been trying to do. For some reason all those possible failures didn't happen on that last try. Feels like my Mac just turned into a Windows 3.0 machine...

Loa

It was scarey reading this as I had the same problems last night. I too got th e POSIX resource busy after creating the first RAID 0. I had 3 drives with 4 partitions each therefore 4 RAID 0's.

I eventually got around the problem by booting using the Snow Leopard installer disk and running Disk Utility from that. Even so, this had to be rebooted after each RAID creation as you could not create any further ones until a rebooted.

All in all it took 2 hours. Worth it though as the speeds are incredable now.

To the other posters who commented on why have partitions? In my case, I needed 3 (set up an extra one for scratch) 1 for the OS, 1 for my data (itunes etc) and one for my EyeTV recordings. Again, why you may ask? Well i have a Macbook which has a 320gig HD and i can easily clone the OS and Data partitions to these at will. If I want a full refresh the OS & Data partitions, If i want just the data then i clone the Data partition. Simple.

 

[cutterman]

Usually the partitions are created after the RAID volume is prepared. This is the procedure Apple recommends if you search their online support, and the method I have used many times without any problems.

Given the serious errors and difficulties described in trying to stripe existing partitions, it would be reasonable to assume that the soft raid system was not designed with that approach in mind. I would bet there is also more system overhead involved with that method, potentially reducing performance.

 

[dknightd]

WTF is wrong with this? Now I know most Mac users don't create RAIDs, but still. Damn!

If you are having all these problems there might be some problem with your machine. That does not sound normal to me.

Were these internal disks or firewire? I've occasionally had strange problems
with DU and firewire drives - DU does not like to see them dismounted

 

[WardC]

I wouldn't create RAIDs from partitioned drives, I would create my RAID from freshly formatted single partition disks only...that is basic rule of thumb. Using Disk Utility, I have never had trouble creating my Striped RAID0 arrays this way, ever. Only takes a couple of seconds!

 

[Loa]

Hello,

I was not looking for answers of explanations. It's just that I'm not used to things being clumsy and crashing on my Mac...

Loa

P.S. If you've never partitioned your drives before RAIDing them, you're losing a lot of performance and should read up on your RAIDs.

 

[nanofrog]

It took me an hour to create two RAID0s from two partitioned drives. An hour. WTF??? ..{snip}..

I'm feeling with you. Have had that experience, too, even with non-partitioned drives.

It was scarey reading this as I had the same problems last night. I too got th e POSIX resource busy after creating the first RAID 0. I had 3 drives with 4 partitions each therefore 4 RAID 0's.

Guys, what version of OS X are you running?

I ask, as I'm wondering if the 10.6.8 update might be the issue (there's another member having an issue with eSATA devices).

Usually the partitions are created after the RAID volume is prepared. This is the procedure Apple recommends if you search their online support, and the method I have used many times without any problems.

Given the serious errors and difficulties described in trying to stripe existing partitions, it would be reasonable to assume that the soft raid system was not designed with that approach in mind. I would bet there is also more system overhead involved with that method, potentially reducing performance.

If you notice, flatfoot isn't running partitioned RAID at all (single partitions on each member in the set). So it's not just in improper methodology/procedure at work here.

We may be seeing another update that messes with storage again... (10.6.3 anyone?). I hope I'm wrong on this, but it needs to be investigated IMO.

 

[Loa]

Hello,

Nano, I'm running 10.6.8 on my 2009 MP. Yet I remember creating a very similar soft RAID0 using 4 drives back in July 2009, with 10.6.4, and having the same kinds of difficulties.

Loa

 

[dknightd]

Hello,

I was not looking for answers of explanations.

With all due respect - THEN WHY DID YOU POST???

 

[derbothaus]

Ha ha.

 

[Loa]

Hello,

Threads that start like this [Rant] mean that you'll get a rant inside.

If the mods want to delete it, fine. Unless Nano can track down an explanation.

Loa

 

[flatfoot]

​

Guys, what version of OS X are you running?

I ask, as I'm wondering if the 10.6.8 update might be the issue (there's another member having an issue with eSATA devices).


If you notice, flatfoot isn't running partitioned RAID at all (single partitions on each member in the set). So it's not just in improper methodology/procedure at work here.

We may be seeing another update that messes with storage again... (10.6.3 anyone?). I hope I'm wrong on this, but it needs to be investigated IMO.

I created my RAID sets "back in the day" under 10.6.3, so for me it had nothing to do with the 10.6.8 update.