Help setting up Raid 0 with two SSD's

[clank72]

Raid is all new to me but I would like to upgrade my velociraptors. I herd striping with two SSD'S is super fast.

I currently have 3 velociraptors installed. Slot 1 is just for Apps (boot disk), Slot 2 are my files, Slot 3 is a backup of slot 2 (time machine). I would like to replace my boot drive (slot 1) with two SSD's under Raid 0. I still have one more slot left (slot 4) so I can installed two SSD's.

Do I need a raid card for doing this?

The Mac I'm installing into is a 2008 2.8 Quad. It's still pretty fast, but I need a boost.
My plan is to get two 120GB Mercury Extremes.

 

[VirtualRain]

Raid is all new to me but I would like to upgrade my velociraptors. I herd striping with two SSD'S is super fast.

I currently have 3 velociraptors installed. Slot 1 is just for Apps (boot disk), Slot 2 are my files, Slot 3 is a backup of slot 2 (time machine). I would like to replace my boot drive (slot 1) with two SSD's under Raid 0. I still have one more slot left (slot 4) so I can installed two SSD's.

Do I need a raid card for doing this?

The Mac I'm installing into is a 2008 2.8 Quad. It's still pretty fast, but I need a boost.
My plan is to get two 120GB Mercury Extremes.

You don't need a RAID card... after you install them and boot to your OSX install media, you'll have an option to run Disk Utility from the menu before the installation. Simply choose RAID, striped, and the disks you want to include and then Disk Utility will format your RAID0 array and allow you to proceed with your installation.

 

[clank72]

Super, thanks I'll give it a shot!

 

[ssgbryan]

I did that with my 2 ssds.

It made Safari snappier on my Mac Pro 1,1.

 

[alphaod]

I couldn't get Lion to install on a RAID 0 of SSDs, so I would stick with Snow Leopard if you want RAID, though your results may vary.

 

[deconstruct60]

Raid is all new to me but I would like to upgrade my velociraptors. I herd striping with two SSD'S is super fast.

I currently have 3 velociraptors installed. Slot 1 is just for Apps (boot disk), ...
... I would like to replace my boot drive (slot 1) with two SSD's under Raid 0.

Do I need a raid card for doing this?

The more illuminating question would be do you did to RAID 0 these at all. One SSD is already "super fast" relative to what you have now. Your applications themselves are only so big. For example if load a 600 MB file (which is still on HDDs) into an app (on a SSD), then , unless the app is extremely weird, most of the time is going to be spent loading the data.
Unless the Apps are much larger than the data, the "super duper ultra" speed of the RAID-0 SSD is only going to show up in dubious benchmarks like "boot time" (like that is done often ) and "open App with no data " ( if loading a browser's large cache file is a primary objective).

You also loose some of the features of Lion when you put the OS on a RAID drive.

http://support.apple.com/kb/HT4649

You can buy a USB thumb drive to make your emergency boot drive (http://support.apple.com/kb/HT4848) to work around the lack of a recovery partition, but that is yet another expense (could pay for that with 2nd SSD money. ). With software RAID, have also removed BootCamp as a future option.

My plan is to get two 120GB Mercury Extremes

Another illuminating question is how full is your Apps drive. If your current Apps drive fills 2 x 120GB about 60-80% full then probably should get a bigger drive. (e.g., some apps have huge library data files). If not a 240GB Electra is a couple $100 cheaper than two 120GB Extremes. If the Apps drive is 20GB can drop down even further.


With a 2008 Mac Pro you are not going to see the top end benchmark times for the Extreme drive because only have SATA 2.0 (3Gbps) on the machine. If intend to move the drives to a faster Mac in a year or so, then perhaps. Otherwise, there will be better SSD values 2-3 years from now when time to replace this base unit.


After that long preamble and if have Lion...

Back up to Time Machine.
Create a USB Thumb drive Recovery image.
replace boot drive and boot off USB to create RAID set up and start TM recovery.


Similar if not Lion (probably already have DVD ).

 

[VirtualRain]

I couldn't get Lion to install on a RAID 0 of SSDs, so I would stick with Snow Leopard if you want RAID, though your results may vary.

Good Point... I don't know if that's been addressed in 10.7.2 but was certainly true in 10.7.0 If it's still the case, either do a clean install of SL on your RAID0 array and then "upgrade" to Lion or try this...

After that long preamble and if have Lion...

Back up to Time Machine.
Create a USB Thumb drive Recovery image.
replace boot drive and boot off USB to create RAID set up and start TM recovery.


Similar if not Lion (probably already have DVD ).

That sounds easier.

The more illuminating question would be do you did to RAID 0 these at all. One SSD is already "super fast" relative to what you have now. Your applications themselves are only so big.

Rather than discourage the use of a RAID0 array, I'd flip this around and say it's a good reason to move some data you use regularly to the SSDs.

 

[alphaod]

Good Point... I don't know if that's been addressed in 10.7.2 but was certainly true in 10.7.0 If it's still the case, either do a clean install of SL on your RAID0 array and then "upgrade" to Lion or try this...

No it has not been fixed. That is the only reason I went from a RAID 0 of three SSDs to just one SSD.

Frankly, I don't think Apple will ever fix it.

Though, another member Schismz, posted in a thread of mine mentioned he installed Lion to a separate drive (no RAID) and then cloned the drive back into a RAID 0 and that seemed to have worked for him.

 

[deconstruct60]

Rather than discourage the use of a RAID0 array, I'd flip this around and say it's a good reason to move some data you use regularly to the SSDs.

The $/MB of SSD is way too far off HDDs (at least after the Thailand flood impact fades way) to be used as targets for digital packrats. If the critical dataset is that large and can afford it then fine. But soaking up MBs just to soak up MBs is off because the $/MB is way off.

HDDs low cost bulk storage.
SDDs high cost frequently accessed data.
Hybrids in the middle.

If someone had sets of larger folders that they shifted workload from week to week on but still occasionally needed another file then a hybrid drive might work. At long as they get "warmed up" on the files going to targeting, hybrids can actually turn in decent performance (if have reasonably large enough SSD cache. 3.5" drive containers would make better platforms for implementing those. )

For most people their "working set" of data moves around over time. That is a good job for either the OS/"File system" and/or the drive to figure out autonomously. It is not a substantially different task from the caching algorithms any decent file system has. Only a longer term view with more storage to leverage the speed-ups out of.

 

[Schismz]

No it has not been fixed. That is the only reason I went from a RAID 0 of three SSDs to just one SSD.

Frankly, I don't think Apple will ever fix it.

Though, another member Schismz, posted in a thread of mine mentioned he installed Lion to a separate drive (no RAID) and then cloned the drive back into a RAID 0 and that seemed to have worked for him.

That would be me, and that's exactly what I did with 10.7.0. I had problems getting Lion to install to RAID0 (although others have apparently experienced no issues). I just did a clean install to a single HDD, then cloned it back to SSD RAID0 using CCC (which does not copy the "Recovery Partition" that doesn't work on RAID anyway).

I originally did this to dual OCZ SSDs in RAID0, then switched over to dual OWC Mercury Extreme 6G's, and experienced no problems in either case.

Dual 240GB OWC SSDs in RAID0 for boot + user (& 4, 3TB Hitachi HDDs in RAID0 for data). 2010 12-core Mac Pro, 48GB.

Average SSD Write = 484MB/sec, Read 526MB/sec.
Average HDD Write = 554MB/sec, Read 575MB/sec.

From the above, 4 very fast Hitachi HDDs in RAID0 beat the dual SSDs, but in the real world, it depends, obviously the latency on the SSDs is much lower/nonexistent (no heads moving across spinning platters to read/write data), and r/w of millions of smaller files all over the boot RAID is much faster with the SSDs.

One caveat as AlphaOD mentioned, Lion's RAID tools are still broken as of 10.7.2, by which I mean to say Disk Utility.app has been fixed enough to display RAID volumes properly (Apple finally fixed this in 10.7.2), but it won't actually do anything with them (such as, for instance, verify).

Disk Utility.app is just a GUI for diskutil, which works fine from shell (diskutil list, followed by diskutil verifyVolume /dev/disk(whatever # you got from the previous list command). You can obtain a full list of supported commands by just typing man diskutil from $hell.

Anyhoo, I have experienced no issues or weird problems with this setup. However, neither Lion's Recovery Partition or FileVault will work on RAID0. If you really want to encrypt something, then use something better like GPG, or make encrypted disc images; so far as the recovery partition goes, if you are running RAID0 then you absolutely need other backups and clones, Recovery Partition won't cut it, unless you like playing russian roulette with your data.

 

[VirtualRain]

The $/MB of SSD is way too far off HDDs (at least after the Thailand flood impact fades way) to be used as targets for digital packrats. If the critical dataset is that large and can afford it then fine. But soaking up MBs just to soak up MBs is off because the $/MB is way off.

HDDs low cost bulk storage.
SDDs high cost frequently accessed data.
Hybrids in the middle.

If someone had sets of larger folders that they shifted workload from week to week on but still occasionally needed another file then a hybrid drive might work. At long as they get "warmed up" on the files going to targeting, hybrids can actually turn in decent performance (if have reasonably large enough SSD cache. 3.5" drive containers would make better platforms for implementing those. )

For most people their "working set" of data moves around over time. That is a good job for either the OS/"File system" and/or the drive to figure out autonomously. It is not a substantially different task from the caching algorithms any decent file system has. Only a longer term view with more storage to leverage the speed-ups out of.

In my case, RAW photo processing... it makes a big difference having my active Aperture Library on solid-state. But obviously I can't keep my entire history of photos on SSDs so it forces me to have multiple libraries. The bigger my SSDs the less time I spend juggling libraries around. And I just upgraded so I probably only have to archive to HD once every 6 months.

Even when I was doing some HD video editing, I would make room on my SSD's to house all the video project files I was working on and then I would archive them to a HD when the project was over.

While I would like to forget about the file system completely and just focus on my work, the realities of not having enough SSD storage to house everything forces me to juggle stuff around. I'm at a point where the overhead isn't a burden and the performance gains are worth it. But everyone's situation is different.

My advice: (1) Buy the most SSD storage you can afford and (2) Fill it up - put stuff you use on it regularly (whatever you do, don't let an SSD sit there with empty space - that's unused performance!)

 

[muski]

Great, but not for the faint of heart...

I have two 120GB SATA III SSD drives installed in my 3.4 GHz i7 iMac, running under RAID 0. It's definitely life on the bleeding edge: it voids your warranty, it's tricky to install and I've had a serious problem with an EFI update. But once over those hurdles, it's fantastic. My disk io speeds are closing in on 1GB/s -- close to ten times faster than my 2TB HD. I keep my OS, Apps, Lightroom DB and recent RAW photos on it. Makes for super zippy photo editing.

I am constantly backing up to a Time Capsule...

When I ordered the machine, I drop-shipped it to OWC and had them install the drives and 16GB of RAM. Two of their 120GB SATA III SSDs were cheaper than the Apple SSD option (which being SATA II, tested at only a little better than 200MB/s.).

 

[LeahHaskell]

Moving this topic from the mac pro 1.1 is undead topic, back to this thread

So overall experience is that Lion is stable on SSD RAID0 on MacPro 5,1 at this point?

I don't know anything about unix, but I can type in diskutil list to check the RAID if it won't work from Disk Utility.

compiling book of nanofrog and hardware RAID. more questions coming

 

[Schismz]

So overall experience is that Lion is stable on SSD RAID0 on MacPro 5,1 at this point?

Yes, exactly. Except "stable" and RAID0 + SSD is kinda an oxymoron.

It's working out okay. Filesystem has not yet been eated by black hole, much sadness, despair, oh NoooOoooz, all my ****** is gone. Oh, no wait, that's why I have backups, oh snap!

When it breaks, you can fix it. The world won't end.

Until it breaks, everything will go MUCH faster.