Comment by stcredzero | Hacker News Reader

Comment by stcredzero | Hacker News Reader

My alternative: Put a 256GB Crucial RealSSD 300 in a 13" Macbook and max-out the RAM. It will be bigger and heavier, with less battery life, but if you already have a Macbook, this is a much cheaper move. The RealSSD has background garbage collection, so you don't have to worry about TRIM. You only need to do two things: 1) noatime and 2) make sure you're using less than 220GB.

I did this, and the performance is fantastic. (Original 13" unibody Macbook with RAM upgraded to 6GB.) Everything happens instantly. I had journalling off, because it increases disk writes by 12%, but OS X compensates by cranking up its RAM cache. Keep journalling on, as it helps boot-up and shut-down happen quickly and things just seem to run faster without the system managing the really large RAM cache to disk. (Another factor: The nasty bug in XCode 3.1 requiring you to reboot your machine to unfreeze the simulator. This makes fast reboots a big win for me. Otherwise, I'd use sleep and only reboot occasionally.)

For increased battery life on the plane, I have a Tekkeon myPower All, which I also sometimes use to power a mobile 4G hotspot. You can find a $14 Magsafe cord on eBay, and solder it to a male Adaptaplug from Radioshack to make yourself an adapter.

EDIT: If you have an older Core Duo plastic Macbook capable of supporting more than 4GB of RAM, then I'd recommend slapping a RealSSD into it. You'll have something lighter than a 13" aluminum with great performance.

So I had to go look up noatime. Here's what I found:

"Linux [and presumably Mac OS X] has a special mount option for file systems called noatime that can be added to each line that addresses one file system in the /etc/fstab file. If a file system has been mounted with this option, reading accesses to the file system will no longer result in an update to the atime information associated with the file like we have explained above. The importance of the noatime setting is that it eliminates the need by the system to make writes to the file system for files which are simply being read. Since writes can be somewhat expensive, this can result in measurable performance gains. Note that the write time information to a file will continue to be updated anytime the file is written to."

(http://tldp.org/LDP/solrhe/Securing-Optimizing-Linux-RH-Edit...).

stcredzero, I'm curious to see how you set up your partitions to take advantage of noatime.

I used the method shown here:

http://blogs.nullvision.com/?p=275

My Macbook 13" alternative was to put a 128gb sandforce SSD into the hard drive bay and move my 500gb into the DVD Drive slot (For iTunes and Movies mainly). I also upped the RAM to 8gb.

It FLIES! And the battery life good.

SSD was my best new (to me) technology of 2010 :)

I was going to go this route, but I found it better to just move all the movies and install DMG onto an external drive. For one thing, I like how quiet my Macbook can be when the only spinning thing is the fan. (The MP3 collection needs to be on the internal drive, though.)

I have done this as well, but I'm a little concerned that the 500gb drive no longer has the sudden motion sensor. I'm thinking about swapping the two drives, but don't know if I'll end up running into hibernate issues or not.

Curious - how does background GC eliminate the need for TRIM?

I know it can use a set of unallocated blocks and clean them and swap them in and out where necessary - but without knowledge of the filesystem structure itself (TRIM) - it's always going to be sub-optimal. You'll have some fast write-space available, but not necessarily the full amount you could.

My understanding is that OS X/HFS+ already optimizes for reusing already allocated blocks. This means that fast write-space is conserved as much as possible at the expense of larger commit-loads from the OS's RAM cache when writing to already allocated blocks.

Also, what I've read seems to indicate that OS X behaves sub-optimally, but this is still good enough to support snappy behavior under normal workloads.

Not sure I follow.... the fast-write space in a non-TRIM device with GC is just some "extra" blocks (or whatever) that are kept aside and now and then swapped out for other in-use blocks (as far as the drive firmware is concerned - the OS has no idea this is going on) - and then the spare blocks are wiped for fast write again, then used when writes are requested.

Really appreciate if you could shed any more light on why OSX would be better at this.. not sure I can picture this.

OS X tries to avoid requesting "new" blocks for write. (AFAIK. Not an expert.)

Are you sure the Unibody Aluminum Macbook (Macbook 5,1) supports 6GB of RAM? I have this laptop and both the apple specs and crucial say it can only support 2x 2GB.

> Are you sure the Unibody Aluminum Macbook (Macbook 5,1) supports 6GB of RAM

The hardware limit is (and has always been) 8GB, the original firmware limit was claimed at 4GB and there's apparently been a firmware update late 2009 (december 8th) which raised the EFI limit. At this point, claims become muddled, it seems you can put 8GB RAM in it but it only sees 6, unless you launch the 64b kernel (apparently)

I put 8GB in my 5,1 (Late 2008 Unibody 13") a few months ago, and it worked great. It's running 10.6 with the default 32bit kernel and was definitely using the full 8GB, so something has definitely changed at some point. For the record, I got the 8GB from OWC.

Macbook 5,1 absolutely supports 6GB, NOT 8GB.

The best summary I've found: http://blog.macsales.com/3291-putting-a-rumor-to-rest-owc-su...

Typing this from a Macbook 5,1 with 8gb onboard. Been running this way for months with no problems.

Under Snow Leopard, at least, this limitation does not apply.

I should have specified the model... I have a 13.3" 2.0GHz MacBook5,1. There is some variation within the 5,1 MacBooks; here's a quote from the discussion attached to that linked article (perhaps you have a 15" MacBook 5,1?)

  As far as the 15" MacBook5,1 models go – The three models released in October 2008, OWC supports to 6GB of RAM:

  MacBook Pro 15″ 2.4GHz
  MacBook Pro 15″ 2.53GHz model w/ExpressCard Slot (Late 2008)
  MacBook Pro 15″ 2.8GHz model w/ExpressCard Slot (Late 2008)

  The two models released March of 2009, OWC and Apple support up to 8GB of memory.
  MacBook Pro 15″ 2.66GHz (All)
  MacBook Pro 15″ 2.93GHz (All)

Nope, 13", 2.4 GHz.

Like so:

[[ Model Name: MacBook Model Identifier: MacBook5,1 Processor Name: Intel Core 2 Duo Processor Speed: 2.4 GHz Number Of Processors: 1 Total Number Of Cores: 2 L2 Cache: 3 MB Memory: 8 GB Bus Speed: 1.07 GHz ]]

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