Help Confirm my Mac Pro SSD/RAID approach

[Avery1]

Hello All,

I know there are some very knowledgeable persons here, so if you have first hand knowledge and confirm (or suggest change) to the following approach to drive setup, I'd appreciate it.

Setting the stage:
I am purchasing a used 2009/4.1 Mac Pro with 2 x 2.66 GHz processors (8 phys core). It may be a bit overkill for my intended work, but after yellow-screen issues with the quad-core imac, I decide to search for a Mac Pro.

Most of my intended uses will not tax the system whatsoever; however, I do plan on doing some editing of HD video from trips, but nothing for money - more as a hobby/personal interest. Maybe 5-30 min movies. I'll be learning/using Adobe Premiere Pro (student pricing beats the pants off FCP). Hopefully I'll get 5 years from this machine.

I do value redundancy in data, and typically try to do a RAID1, where possible.

I've spent some time diving into the forums, and here's my intended approach:

- Replace boot drive with an Intel 80GB SSD for OS+Applications
- Install the SSD to the second Optical Drive Bay
- Use the remaining 4 drive bays to create a single mirrored and striped RAID 1+0 partition, using Mac OS 10.6.3 Software RAID
- My current plans would be to use three Samsung HD501LJ 500GB drives from my NAS (will upgrade the NAS with larger drives) and the one existing internal stock 640GB drive


General feedback on this approach?
Sufficiently fast for what I'll be using it for?
Any issues using the current internal (non-matching) drive for the 4th RAID drive? I could purchase another HD501LJ if that decreases risk, but would prefer not to.
Any issues running VMWare on this RAID setup?
Other recommendations?

Thanks!
Avery

 

[nanofrog]

Looks good. And Yes, you can mix drives. So at least try the OEM disk + 3x you want to use before buying any additional disks (it will work though, unless you've a bad drive).

As per the VM aspect, check with the VM software vendor (compatibility, as it's a software implementation), as they're not all the same. Performance is fine.

 

[gglockner]

No problems with running VMWare on RAID, even off software RAID. This is what I do.

As for data safety, just keep in mind that RAID-1 is nice but only protects you from hard disk failure. It doesn't protect you from user error, data corruption, theft, fire, flood, etc. I highly recommend reading "Take Control of Mac OS X Backups" by Joe Kissell, even if you're already familiar with backup strategies.

 

[psychometry]

Your setup sounds like what I'm considering for my 2010 MP. I would also look into a hardware RAID card, too.

On a side note, does anyone here know if there is a good way to mount a second SSD somewhere in the case? Is there a way to fit two separate SSDs in the spare optical bay? You could then RAID0 your two SSDs for your boot drive and applications, giving you a decent performance boost.

 

[nanofrog]

No problems with running VMWare on RAID, even off software RAID. This is what I do.

Is it that way with Parallels though?
(I seem to recall that this aspect may have been part of the differences as to what works with which VM). Then there's freeware out there (not used it, so I've no idea).

 

[Transporteur]

Is it that way with Parallels though?
(I seem to recall that this aspect may have been part of the differences as to what works with which VM). Then there's freeware out there (not used it, so I've no idea).

Nope. Both Parallels and VMWare run flawless off a OS X software RAID.
Got a bunch of Windows and Linux installations on a 2 drive RAID0 and never had a single problem. I do, however, prefer virtual machines on a SSD. Way snappier than on a RAID array.

 

[nanofrog]

Nope. Both Parallels and VMWare run flawless off a OS X software RAID.
Got a bunch of Windows and Linux installations on a 2 drive RAID0 and never had a single problem. I do, however, prefer virtual machines on a SSD. Way snappier than on a RAID array.

I've not tested VM's under OS X using software RAID, so I wasn't certain (hardware RAID + Linux so far for me).

 

[gglockner]

Folks, there should be no problem with running off a RAID. The host operating system (OS X) manages the RAID; VMWare (or Parallels) simply sees files on the Mac's filesystem, and the guest operating system (Windows, Linux, whatever) simply sees a virtualized hard drive.

 

[nanofrog]

Folks, there should be no problem with running off a RAID. The host operating system (OS X) manages the RAID; VMWare (or Parallels) simply seems files on the Mac's filesystem, and the guest operating system (Windows, Linux, whatever) simply sees a virtualized hard drive.

Yes, but I didn't know if it worked properly with the available VM software (some wierd interaction with hardware, that causes problems - OS X's implementation of software RAID /= to how it's done under Windows or Linux. seems the offsets are different).

So I wasn't sure of Reality vs. Theory in the case of a specific version (Parallels vs. Fusion). I do recall there are a couple of odd issues mentioned that users encountered between them (comments going back and forth as which does/doesn't have what issue/s). It's here in MR somewhere.

 

[Avery1]

nanofrog -- Thanks for the setup confirmation; i've read several of your posts, and you are certainly knowledgable

gglockner/transporteur -- Thanks for the VMWare/RAID confirmation. Sounds like it works well for you. i will also have a couple rotating backups to the NAS, so we should be good there. Thanks for pointing out the corruption issue -- I think many folks don't realize this.


I see two product numbers for the intel 80GB SSD on Newegg.
SSDSA2M080G2XXX and SSDSA2MH080G2R5
The only 'spec' difference I see listed is that the later has the 3.5" -> 2.5" adapter. Sound accurate? Are these the 'right ones' to buy if I'm getting an SSD for the boot disk?

Does anyone know of any reasons I wouldn't want to have all my standard data and video scratch area on the same RAID group/partition (4 drives as Raid 1+0 versus any other setup such as 2@ RAID1 for data and 2@RAID0 for scratch, etc)?

BTW -- I did end up getting the MP today, a pretty good deal at about 1/2 of retail for a March 2009 unit. The yellow iMac is goin' back!!!

 

[nanofrog]

I see two product numbers for the intel 80GB SSD on Newegg.
SSDSA2M080G2XXX and SSDSA2MH080G2R5
The only 'spec' difference I see listed is that the later has the 3.5" -> 2.5" adapter. Sound accurate? Are these the 'right ones' to buy if I'm getting an SSD for the boot disk?

Yes, they're fine, as they're the same drive. One is an OEM version, and the other is a Retail unit (includes the adapter and comes in a box).

Does anyone know of any reasons I wouldn't want to have all my standard data and video scratch area on the same RAID group/partition (4 drives as Raid 1+0 versus any other setup such as 2@ RAID1 for data and 2@RAID0 for scratch, etc)?

Place all the user and scratch data on the array (10).

 

[Avery1]

Yes, they're fine, as they're the same drive. One is an OEM version, and the other is a Retail unit (includes the adapter and comes in a box).


Place all the user and scratch data on the array (10).

Thanks -- just wanted to ensure that scratch area didn't need to be logically separated from any other data for performance or other reasons.


Are there any key threads or pointers regarding on separation of data/migration to another disk/partition that I should be searching-for?

I.E. I know I can easily move 98% of my data elsewhere (as it's under /data), but I'm not sure if moving any other data/locations (where cache, application configuration files, downloads, etc are written) is key?

Lastly, does anyone know how the real-world failure/reliability rates of these higher-end SSDs compare to a HDDs? I ask mainly because I usually like having redundancy on the boot disk. I know they are lower-risk for failure due to no moving parts, but not sure how much lower. Perhaps failure is a non-issue, or perhaps it's still a real risk? I will have backups, of course.

 

[nanofrog]

Lastly, does anyone know how the real-world failure/reliability rates of these higher-end SSDs compare to a HDDs? I ask mainly because I usually like having redundancy on the boot disk. I know they are lower-risk for failure due to no moving parts, but not sure how much lower. Perhaps failure is a non-issue, or perhaps it's still a real risk? I will have backups, of course.

SSD's (particularly MLC Flash based units), are best used as read drives, and why they're fine for OS/application disks.

Not so much for writes. They may have nice looking specs, but it's misleading if you don't realize what they're doing (statistical manipulation by dumping the values of the worst 10% of cells). SLC fare better (it's capable of 10x more writes than MLC based on flash maker's specs), but are much more expensive.

 

[gglockner]

My personal opinion is that the jury is still out on the reliability of SSDs. True, SSDs ought to be more reliable due to the lack of moving parts. But frankly, SSDs haven't been widely available long enough to get real-world longevity data. Yes, flash memory has been around a few years, but your average iPod or USB flash drive doesn't get as many read/write cycles as a hard drive.

That said, I've been wondering as to whether it's a good idea to do RAID 0+1 with SSDs. I can understand RAID 0, but RAID 1 or 0+1? Seems overkill to me. If I were spending that much money on storage, I'd look into the OWC Mercury Extreme SSDs. They already have extra space for parity, so doing RAID 1 or RAID 0+1 with these is overkill. You could get a pair of them for RAID 0 and be in great shape.

As for me, I'm debating whether to go with Intel or OWC. Intel is cheaper in terms of $/GB and it's a company with a solid track record. But OWC seems to have the edge on performance, along with some promises of avoiding performance degradation.

 

[nanofrog]

My personal opinion is that the jury is still out on the reliability of SSDs. True, SSDs ought to be more reliable due to the lack of moving parts. But frankly, SSDs haven't been widely available long enough to get real-world longevity data. Yes, flash memory has been around a few years, but your average iPod or USB flash drive doesn't get as many read/write cycles as a hard drive.

For general use, definitely. There does seem to be sufficient data to gain some idea of reliablility for reads though (using flash maker's data).

But writes, no. Worse yet, the early units have known flaws, and OS support isn't universal yet. All of which will skew the data for awhile (unless that data is eliminated from the analysis).

That said, I've been wondering as to whether it's a good idea to do RAID 0+1 with SSDs. I can understand RAID 0, but RAID 1 or 0+1? Seems overkill to me. If I were spending that much money on storage, I'd look into the OWC Mercury Extreme SSDs. They already have extra space for parity, so doing RAID 1 or RAID 0+1 with these is overkill. You could get a pair of them for RAID 0 and be in great shape.

I wouldn't go past a stripe set with SSD's until there's more data to determine if they're stable enough for it, and even more so with parity based arrays (I'm not that convinced even SLC is up to the task long term). For an MTBR of 3yrs, maybe with SLC. Past that... not so much.

 

[Loa]

Your setup sounds like what I'm considering for my 2010 MP. I would also look into a hardware RAID card, too.

Don't pay a RAID card without knowing exactly what you're getting into. From what the OP has described, he doesn't need a RAID card.

On a side note, does anyone here know if there is a good way to mount a second SSD somewhere in the case? Is there a way to fit two separate SSDs in the spare optical bay?

There are very cheap ways to "mount" three SSDs in a single optical bay (5-10$ http://www.xpcgear.com/scythe-2-5-to-5-25-bay-rafter.html). Heck there's even a more expensive way to fit four! (~60$ http://www.addonics.com/products/raid_system/ae4rcs25nsa.asp)

The problem is not the mounting, but the SATA+power cables. For that you need SATA cards, SATA cables and a way to split the power from somewhere else. Not for the faint of heart!

As for the dual SSDs in a RAID0 for performance, I'm not so sure. Sure you'd get lots of "on paper" performance, but I've yet to see some significant real world performance of RAIDing 2 (good) SSDs.

Most people claim it's uber-fast, but how about some real application benchmarks?

Loa

 

[Avery1]

I can definitely understand how data would be skewed with the OS support and the early-adopter situations.

I'm still having trouble grasping what type of stability I will likely get out of one of these Intels as a boot disk. Based on your historical observations of the recent year or so (when this has taken off), do each of you think the stability is about on-par with a modern HDD, somewhat better, or significantly better?

Having a general feel for this will let me know how concerned I should be with the frequency and robustness of my backup approach since it would not be in RAID 1

 

[Loa]

Hello,

First off: regardless of the system you have and the type of storage you chose, a true back-up solution is a necessity. Period.

Also remember that a RAID1 (or any RAID type with parity) is NOT, I repeat NOT a back-up solution. In fact, unless you run a mission critical system where top client dollars may be lost if a drive physically fails, RAID1 is not very useful these days.

As for SSD stability, I'm not sure what you mean by the term "stability". I've been using an Intel 80GB G2 SSD as my OS volume for the past 6 months or so, and everything has been flawless so far. I would never go back to using a mechanical HD, or even a RAID0 (as I had before getting the SSD) of mechanical drives for my OS. (I still use a RAID0 of 4 regular HDs, but for everything not-OS.)

The UBE (unrecoverable bit error) of a SSD is far lower (worse) than a mechanical HD, but then again, if it was *that* bad in the real world, SSDs wouldn't be flying off the shelves.

In any case with a good, daily back-up solution, even a bad crash is not the end of the world.

Back-up solutions can be very simple: get a mechanical drive that's bigger than your entire system if possible, or at least bigger than what you need to back-up. Use Time Machine if you dare, or other apps like Carbon Copy Cloner (the one I chose) to get more control over your back-ups.

If you want to go a step further, buy two drives, and have one of your back-ups "off-site" (i.e. at your parent's house, or a friend's). Do your back-ups on both drives, then store one of them off-site. Rotate your back-ups once a week or so, keeping the off-site back-up up-to-date.

But through all this remember: HDs (of all kind) do break down, but it's rare. I've never, in 20 years, had to rely on a back-up for anything significant. I've had 2 HDs fail on me, but gracefully enough so that I managed to make a last back-up just before throwing them in the trash. No data lost.

Back-ups are essential, but think of them as fire alarms. You HAVE to have on in your house, but chances are you won't be using it for more than burnt toast!



Loa