How To: Apple MacBook Pro RAID 0 Array with 2 Intel X25-M SSDs | Hacker News Reader

How To: Apple MacBook Pro RAID 0 Array with 2 Intel X25-M SSDs

paulstamatiou.com

40 pointsPStamatiou14 comments

The article somewhat implies that running TRIM from Windows 7 on a dual-boot (with OS X) system is useful - wouldn't that not be the case though since Windows 7 is not going to know what blocks are in use on the HFS+ partitions?

It's true that Windows can't trim HFS+, but the free space created by Windows will make the SSD faster even when you boot back into OS X.

If you really really feel the need for speed in OS X, I recommend the host protected area trick since it's a one-time optimization.

Can you elaborate on what the "host protected area trick" is?

http://www.mail-archive.com/misc@openbsd.org/msg82811.html

Setting the HPA (immediately after secure erase) ensures that some LBAs always remain unallocated and should give the GC more candidate erase blocks to work with, increasing random write performance. Or at least that's how I understand it.

However, there already is a certain amount of free space allocated for this task. On the Intel drives, it's the difference between 80GiB and 80GB; the latter is the maximum addressable by the OS, the former is the actual capacity of the flash chips. Flash chips always have a power-of-2 capacity, and there are 5, 10 or 20 chips in the various intel drives.

Why not RAID-1? RAID-0 on a technology that is known to die relatively faster than HDD's seems risky. Plus, you should get a read speed boost from it too.

Hey Tim! I was just at Ignition Alley today, in the loud room, working on this post.

I have lots of backups in place - files I don't touch in more than a week get moved to S3, as well as Time Machine and a working clone of the drive made every week.

That being said, RAID 0 gives me more space and is faster for reads and writes (that are larger than the block size that is)! Risky indeed though. I touched up on this aspect at the end of the article, and also noted that this setup will only exist on my MBP for 9 mons or so, at which point I'll upgrade to some faster SSDs.

Why RAID-anything in a laptop? A single Intel SSD is pretty darn fast, and the second bay is more useful as a large-capacity spinning hard drive (unless you need the optical drive, of course). I have my MBP set up this way and I've been very pleased with it.

For me at least: the single SSD got boring after a while and I wanted to get better speeds. As for storage I have a 2TB (RAID 0 as well) HTPC ( http://paulstamatiou.com/how-to-build-microsoft-windows-7-in... ) that keeps most of my media and usenet junk, then an external for other stuff.

IIRC, Intel specify a lifetime of at least 5 years for "normal use", with a warranty of 3 years. In my experience, you're pretty lucky if your laptop hard disk lasts 5 years; of course, the SSDs haven't been out for that long, so who knows.

My first SSD (first gen X25-M) died in ~9 months. Still not sure if it was the controller or just mass failure of the flash mem. Either way Intel sent a new one in just a few days.

RAID-1 is a (very expensive in this case) waste of space when you already have a perfectly good backup system in place.

What's sad is that the chipset in the MacBook Pro he has can do hardware RAID, Apple just doesn't support it in EFI.

It's Nvidia's MCP79 (of the nForce 790 SLI)

Apple already has a RAID implementation. It's software based but the performance is just as good as the hostRAID. It also has the benefit of being swappable to any other Mac system unlike hostRAID which is chipset dependent.

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