Does filling up an SSD slow it down?

I've done Google queries on this subject and seem to get conflicting answers. Conventional HDD wisdom is that filling it up to capacity is bad, but I want to know if this applies to SSD's as well.

I've heard some sources say that SSD's should not suffer any significant losses from filling it up:
MPG - Mac Performance 102: Storage - Why You Need More Space Than You You Need

Browsing forums, however, I've seen people claim that you should not fill up your SSD. I'm thinking that perhaps it depends heavily on the model of the drive? I'd like to know how this would generally apply to SSDs, but specifically I'm looking at the Samsung 830 series and the Intel 320.

 

When you use a hard drive up it tends to get more and more fragmented as the OS is constantly reading/writing data. If a hard drive does near full capacity, and it is fragmented, that almost guarantees that you are going to suffer high latency and low throughput since the drive has to constantly access various portions of the disk to do the most meaningless of tasks.

With SSDs, read/write latency is theoretically (usually) constant across the entire drive. Defrag is no longer needed, and you no longer have to be as concerned with fragmentation of files.

Where SSDs do have a problem with a nearly full capacity is when you are writing to the disk. NAND cells can only withstand a few thousand writes before becoming damaged. If the drive is almost full, and you are trying to write data to the drive continually, then you run the risk of burning out the unused portion of the drive faster.

It isn't good to completely fill up either a hard drive or a solid state drive, but the reasons why are completely different.

 

Thanks, that's good information Greg.

Is there a % of the drive you would recommend leaving free?

 

For now, i'd keep the drive at a max of 80% full. What Greg didn't mention as well is that the way that SSDs are made, to achieve the high write speeds they have, the memory you are writing to on the SSD has to be empty. Since when you delete data, the OS only marks the space as free (it doesn't actually erase the data), the SSD's garbage collection has to do it's work and erase the NAND memory marked as empty. To perform efficiently, garbage collection, needs a minimum amount of free space on the drive as well which is another reason not to have it full.

Here's more on the subject: AnandTech - The SSD Anthology: Understanding SSDs and New Drives from OCZ.

 

Always have at least 20% free space on SSD and 15% on a HDD. Its just good practice to never fill up any drive all the way.

Although some SSD controllers can have better low space performance than others.

 

are you sure you're describing that right?

what does endurance have to do with speeds before you start to lose significant amounts of cells?

 

What greg posted might not directly have to do with speed, but it's another reason not to fill a SSD, wear leveling only goes so far.

 

I can tell you, my OCZ Agility 2 60 GB in my Vostro 1500 was 80%+ full, and performance has significantly gone down, boot up speed, read/write speeds.

 

Except when you use an OS and SSD which both support TRIM. With TRIM fully enabled, a delete should erase cells those cells on disk so they are ready for the next write operation. See AnandTech - The SSD Anthology: Understanding SSDs and New Drives from OCZ

It seems for SSDs with SandForce controllers more free space is required for the drive not to hit other performance problems. -

- AnandTech - Intel SSD 520 Review: Cherryville Brings Reliability to SandForce

 

TRIM does alleviate the problem somewhat, but it does not fix things completely, if you abuse the drive at near full capacity, performance will still decrease as was the case for Tsunade's Agility 2. Correct me if i'm wrong, but doesn't TRIM take some time to perform it's operations if you're using the drive somewhat intensively as well?

 

Well I freed up space from 91% to 76%, didn't really make a difference. I'm about to sell my 60 GB Agility 2 though, no more OCZ/SandForce for me!



to

 

For the 60GB , they already reserve a few GB for over provisioning hence the 60GB

 

Older drives do not have TRIM, therefore still leave pages in un-filled blocks.

I haven't tried it, as i have a TRIM drive, but there are some utilities that will perform a TRIM function for you.

Has anyone tried anything like this? SSD Drive Tweaker

 

I was merely pointing out that when LBAs ARE deleted on a fully supported TRIM SSD/OS, the drive physically resets the NAND cells so they can be written next time around. And yes, deletes with TRIM enabled are slower than deletes without, as the cells must be read from disk, reset for deleted LBAs, and then written back out. This is different of how a platter based drive works where the blocks on disk are just marked invalid, but the data is still physically there which was mentioned in your post.

In regards to Agility 2/ SandForce, since I don't have that kind of drive, I cannot comment on "why" this is the case, all I can do is point to what other reviewers have said. However, I don't think deletes/TRIM are the problem here, as we're now talking performance once the drive hits a certain capacity - even if you don't even do any deletes.

How did you free up space? Is it possibly still in the recycle bin/garbage can? If not and the files have truly been deleted, have you thought about taking a disk image/backup, running a secure erase, restoring the disk and checking if that fixed things?

 

Even if your drive is nearly full, it will still execute active wear leveling, basically move data around so that there is as close to even wear across all blocks as possible. So it's not likely you'll wear out an 8GB block of data because that's all that's free.

And even if you reduced from 91% to 76% that's still quite full. It takes a while for garbage collection to work especially after deleting a lot of data. If you delete a lot of data, especially when near full capacity (as in your 91%), make sure your laptop doesn't sleep or hard drive doesn't shut off, log off (don't just lock) your machine, and leave it on overnight. Reboot in the morning, and it should show improvements.

If not, then secure erase should bring it back to close to full performance.

 

Does Win 7 Defrag offer any level of trimming?

 

Not entirely. I guess if a defrag moves things around at the byte level then it may get some of those cells, but not all. If there are blocks from deleted files that nothing points to, a defrag wouldn't necessarily move things to/from a NAND cell.

Regardless, a defrag unnecessarily writes data to new cells, and that would decrease the number of writes of any given NAND cell as fragmentation is not bottleneck on an SSD. So, I would say using defrag as a way to TRIM would in the end cause more harm than good.

 

No, no no! Defrag is nothing like TRIM. NEVER DEFRAG AN SSD! Well, you can, but it's just putting extra writes that aren't needed. It's working double hard then. Everything is done hardware level, well except TRIM, and all that does it tell the system a cell is ok to clear/delete to the garbage collection routine. But even if you didn't TRIM with enough idle time the garbage collection routine would clean it all up anyhow. And actually if you have less than 50% used on your SSD, chances are that lack of TRIM would hardly be noticeable because there's enough free cells for the system to use, given your SSD has enough idle time.

That's the other thing if you use your SSD aggressively from time to time make sure it has some idle time to clean up.

 

This. I once saw a guy defrag his Intel X25-M G2 80 GB. It had horrendous performance after that, he ended up returning the SSD. Don't do it.

 

That's probably kind of extreme, but yeah, defragging only has detrimental effects on SSDs.

As far as filling up an SSD, I didn't notice any detrimental effects on my Intel G2 80GB when I filled it up past 90%, although I usually have it at below 70% usage (now at 66%).

 

Intel X25-M are great drives. Far from the fastest, but reliable controllers and stable performance. It's too bad Intel got out of the controller game.

 

oh dear lordy. I'm going to restate the DO NOT DEFRAG for ANY reason.

even without controllers, intel seems pretty reliable. I only remember the 320 8mb bug; has the 520 been having problems?

 

No need to be dramatic about it; Its not like a Defrag on the SSD will harm it any more than just an extra write or two when it runs.

Its useless, but it wont brick your drive. I was just curious if there was any page-level cleanup options.

 

It was an interesting question, and no one seems to have tried to answer it, but I guess is that probably no one really knows.

Regardless, I stand by my statement that it *might* do something, but then again, it might not. In the end, reducing the number of writes by defragging on your drive in order to fix this is doing more harm than good.

On a different note, only HTWingNut mentioned is a drive's Garbage Collection (GC) utility. No need to try crazy things like defrag to clean up an SSD, when your drive already supports GC - as most of them still have GC routines. Just boot up, log out (if you can), and make sure the SSD stays idle (no virus scanning, indexing, etc.) so the GC can run and clean up the used, non-empty NAND cells.

 

This was so much simpler in the 90s.. when your RAM Drive was composed of SIMMS that lost everything when you rebooted.

 

I suggest it's time to go "Back to the Future." Dah, Doh, Dah.... But you'll need 1.21 jigga-whats, not gigawatts.

Anyways, with 32GB of RAM in a lappy nowadays, no reason to not use that extra memory as a RAM drive if you're so inclined.

 

I had a 4mb One and it was the Schnozz!

ran games like lightning.. i used to think.. man.. one day in the future they should replace hard drives with these.. bet you get even get a 100mb one! Woah!



But.. Nostalgia Aside, really, the problem with the SSDs of today is mis-information. It is a new technology and should be dead simple, but it appears there is more to it than people realize. I wish the manufacturers would do a better job of putting out "Drive care" instructions.

 

It is dead simple imo. Buy the cheapest 1 last gen or previous gen(trim supported), slot it in,install win 7, done. (slotting in and installing win7 may post difficulty for some but still)

 

Ha yeah +1. I had an Amiga 500 which came standard with 512KB RAM. I upgraded to 1.5MB and had a 500MB RAM cache. Ah those were the days.

 

I have 77GB available out of 320GB on my MBP. Does that mean that I should have about 120GB available at least for better performance?

 

You have a 320GB SSD?

 

For anyone worrying about wear leveling, modern SSDs "reshuffle" the content to even out wear when needed, so there isn't much to worry. If a part of the drive gets used too much the controller will try to avoid using it.

 

320GB SSDs do exist: OCZ Vertex 2 320GB SATA II 2.5-inch Internal Solid State Drive: Amazon.co.uk: Computers & Accessories

 

Mr.Koala,

You do realize that you're replying to a year+ old thread right...

 

Sorry for the bump. Didn't realize it.

How exactly did I get into this thread...