Computer Upgrades: RAM vs. SSD

[JohnFul]

On a slightly different topic...

I have a Thinkpad T60 laptop. Last week was the third time I've lost a hard drive in 18 month. This time, instead of another Hitachi 7200RPM SATA II 2.5" hard Drive, I bought a Kingston SSDNow V series Solid State Device.

I had already bumped the RAM up from 2GB to 4GB in the laptop. The CPU is a dual core Intel T5600. In that it's a laptop, I won't be upgrading that. Of the two now completed upgrades, RAM and SSD, I'd have to say that by far the greatest performance increase came from the SSD.

Even after the RAM upgrade and changing the XP memory manager settings to load the kernel and kernal mode drivers in RAM, I still had long boot time, long application load time, slow browsing, etc. After upgrading to the SSD, my boot time is 15 seconds. Applications pop, and browsing is much faster. I then did the disk2vhd thing on Friday and loaded the laptop Hyper-V. I just run my "old" laptop in a VM until I get around to migrating everything off of it.

I have the 128GB version of the Kingston SSD, which runs $250 on NewEgg. This is also a 64GB version for $140 and a 30GB version for $90. In order to upgrade the RAM from 2GB to 4GB, you replace the two 1GB SO-DIMM modules with 2GB modules. THe cost of the RAM upgrade was $90. The RAM upgrade resulted in a noticable but not spectacular performance boost. The SSD upgrade was nothing short of spectacular.

Windows has a page file, and unix/linux has a swap file. When you need to load something into memory, something generally gets paged to disk. I think it was Jeff Barrymam who referred to this as zarking in "the paging game" http://www.sacbusiness.org/cs/hesterj/T ... 20Game.htm. By putting just the OS volume (including the swap or page file) certainly did dramatically increase performance.

IF you are considering increasing RAM soley to improve performance (not because you need more RAM to run a specif application or to host more VMs) then consider that a 2GB RAM upgrade cost about as much as the 30GB SSD. Buying the SSD and putting the OS volume on it (take the original had drive and use it as a second drive to store colder data) provides a much larger performance increase for the same amount. Of course, if money is no object then do both

J

[CaptainBeowulf]

I look forward to using SSDs as the boot drives in any machines I have. However, I'm waiting another year or two until prices come down further and volumes increase.

But yeah, if a system has 4GB or more of RAM I would suggest an SSD is a better upgrade than more RAM.

[kunkmiester]

Big concern I've seen with the SSDs is life. You're writing them a lot more than a thumb drive, and they supposedly don't last nearly as long as a standard hard drive. How long are they supposed to last these days?

[JohnFul]

There are two main types of SSD, SLC and MLC. SLC NAND has a rating of 100,000 MTBF. MLC NAND has a rating of 10,000 MTBF. In addition, SSD is a block erase device. You can read any location randomly, but you have to erase a block before you can write to any location on that block. Reads on an SSD are generally phenominal; writes are marginally better than a 15K RPM Enterprise class Fibre Channel disk.

Internally, an SSD has a flash controller, some RAM, a cap to keep power to the RAM long enough to write the contents should power fail, and raw Flash. The manufacturers use two main strategies to extend the life of the device. The first is to internally overprovision cells. When a write error happens, that cell is marked bad a a spare is mapped in it's place. The other method is called wear leveling. The controller spreads the writes out over all the cells in the device to prevent any one cell from being written significantly more often than any other cell.

Between the two methods, they are generally effective at extending the life of the device. Most MLC SSDs have a warranty of at least 3 years, and SLC SSDs five years. It is true that they are about 8x the cost of a comparable mechanical disk. SSD is a long way from being cost effective as a general disk replacement. The idea is to use a relatively small device to replace the OS volume, and use a large cheap mechanical disk as general data storage. Most of the price movement lately has been due to the introduction of MLC devices. The Kingston device I have is MLC. Still, 3 years is 5 times longer than any of the 3 Hitachi hard drives have lasted in my laptop.

You can find some devices around 30GB in size in the $80-90 price range. Make sure you check the specifications before you buy. Not all SSDs are created equal. Write performance particularly is impacted by the amount of cache RAM used to stage writes, the number of erase blocks, and the block size. The Kingston has 200MB max read throughput and 110MB max write throughput. I believe there is an OCZ model that has 250MB/170MB, but it's significantly more expensive. There's also a RIDATA model that's 68MB/50MB and cost $10 more than the Kingston. It definitely pays to do your homework.

J

[DeltaV]

Still, 3 years is 5 times longer than any of the 3 Hitachi hard drives have lasted in my laptop.

I like the idea of SSDs, but am also concerned about longevity. I have an old laptop with a Hitachi drive that's going on 9 years now (no longer my main machine), but I never let it get bumped around while the platter is spinning.