The SSD Relapse: Understanding and Choosing the Best SSD
by Anand Lal Shimpi on August 30, 2009 12:00 AM EST- Posted in
- Storage
Impact of Idle Garbage Collection
The other option that Indilinx provides its users to improve used performance is something called idle or background garbage collection. The idea is that without any effort on your or the OS’ part your drive, while idle, will defragment itself.
The feature was actually first introduced by Samsung for its RBB based drives, but I’ll get to the issues with Samsung’s drives momentarily.
It either works by looking at the data on the drive and organizing it into a less fragmented state, or by looking at the file system on the drive and attempting to TRIM based on what it finds. Both Indilinx and Samsung have attempted to implement this sort of idle garbage collection and it appears they do it in different ways. While the end result is the same, how they get there determines the usefulness of this feature.
In the first scenario, this is not simply TRIMing the contents of the drive, the drive doesn’t know what to TRIM; it must still keep track of all data. Instead, the drive is re-organizing its data to maximize performance.
The second scenario requires a compatible file system (allegedly NTFS for the Samsung drives) and then the data is actually TRIMed as it would be with the TRIM instruction.
Details are slim, but the idle garbage collection does work in improving performance:
| PCMark Vantage HDD Score | New | "Used" | After TRIM/Idle GC | % of New Perf |
| Corsair P256 (Samsung MLC) | 26607 | 18786 | 24317 | 91% |
Presumably this isn’t without some impact to battery life in a notebook. Furthermore, it’s impossible to tell what impact this has on the lifespan of the drive. If a drive is simply reorganizing data on the fly into a better (higher performing) state, that’s a lot of reads and writes when you’re doing nothing at all. And unfortunately, there’s no way to switch it off.
While Indilinx is following in Samsung's footsteps with enabling idle garbage collection, I believe it's a mistake. Personally, real TRIM support (or at least the wiper tool) is the way to go and it sounds like we’ll be getting it for most if not all of these SSDs in the next couple of months. Idle garbage collection worries me.
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sotoa - Friday, September 4, 2009 - link
Another great article. You making me drool over these SSD's!I can't wait till Win7 comes to my door so I can finally get an SSD for my laptop.
Hopefully prices will drop some more by then and Trim firmware will be available.
lordmetroid - Thursday, September 3, 2009 - link
I use them both because they are damn good and explanatory suffixes. It is 2009, soon 2010 I think we can at least get the suffixes correct, if someone doesn't know what they mean, wikipedia has answers.AnnonymousCoward - Saturday, September 5, 2009 - link
As someone who's particular about using SI and being correct, I think it's better to stick to GB for the sake of simplicity and consistency. The tiny inaccuracy is almost always irrelevant, and as long as all storage products advertise in GB, it wouldn't make sense to speak in terms of GiB.Touche - Thursday, September 3, 2009 - link
Both articles emphasize Intel's performance lead, but, looking at real world tests, the difference between it and Vertex is really small. Not hardly enough to justify the price difference. I feel like the articles are giving an impression that Intel is in a league of its own when in fact it's only marginally faster.smjohns - Tuesday, September 8, 2009 - link
This is where I struggle. It is all very well quoting lots of stats about all these drives but what I really want to know is if I went for Intel over the OCZ Vertex (non-turbo) where would I really notice the difference in performance on a laptop?Would it be slower start up / shut down?
Slower application response times?
Speed at opening large zipped files?
Copying / processing large video files?
If the difference is that slim then I guess it is down to just a personal preference....
morrie - Thursday, September 3, 2009 - link
I've made it a habit of securely deleting files by using "shred" like this: shred -fuvz, and accepting the default number of passes, 25. Looks like this security practice is now out, as the "wear" on the drive would be at least 25x faster, bringing the stated life cycles closer to having an impact on drive longevity. So what's the alternative solution for securely deleting a file? Got to "delete" and forget about security? Or "shred" with a lower number of passes, say 7 or 10, and be sure to purchase a non-Intel drive with the ten year warranty and hope that the company is still in business, and in the hard drive business, should you need warranty service in the outer years...Rasterman - Wednesday, September 16, 2009 - link
watching too much CSI, there is an article somewhere i read by a data repair tech who works in one of the multi-million dollar data recovery labs, basically he said writing over it once is all you should do and even that is overkill 99% of the time. theoretically it is possible to even recover that _sometimes_, but the expense required is so high that unless you are committing a billion dollar fraud or are the secretary to osama bin laden no one will ever try to recover such data. chances are if you are in such circles you can afford a new drive 25x more often. and if you have such information or knowledge wouldn't be far easier and cheaper to simply beat it out of you than trying to recover a deleted drive?iamezza - Friday, September 4, 2009 - link
1 pass should be sufficient for most purposes. Unless you happen to be working on some _extremely_ sensitive/important data.derkurt - Thursday, September 3, 2009 - link
I may be wrong on this, but I'd assume that once TRIM is enabled, a file is securely deleted if it has been deleted on the filesystem level. However, it might depend on the firmware when exactly the drive is going to actually delete the flash blocks which are marked as deletable by TRIM. For performance reasons the drive should do that as soon as possible after a TRIM command, but also preferably at a time when there is not much "action" going on - after all, the whole point of TRIM is to change the time of block erasing flash cells to a point where the drive is idle.
morrie - Thursday, September 3, 2009 - link
That's on a Linux system btwAs to aligning drives...how about an update to the article on what needs to be done/ensured, if anything, for using the drives with a Linux OS?