SSD performance on nearly full disks

[xwb]

Lots of people rave about how fast SSDs are but what is the performance like when the disk is very full, say with 200Mb remaining. Do operations take forever to complete?

On normal hard disks, performance for Windows is pretty crap once you get below 1Gb. For instance, if the remaining disk space is 200Mb, just closing explorer can take in the region of 4 minutes. Logging in takes almost 5 minutes and shutting down takes almost 10 minutes. Had this when I was on holiday. Went with 10Gb free. I thought that was enough for photos. After a few days, I was down to 200Mb! That is when the massive slowdown started.

Does anyone have first hand experience on running SSDs on systems that are nearly full?

 

[rclarke250]

Well, I had my swap space on another drive, but I was running a 96Gb ssd, and it was over 95Gb full, and never had a slow down. Just messages about full disk. Swapped it out for a 256Gb drive, and I have space again, lol.

 

[xwb]

Thanks

The reason why I'm asking is because I did a search and there seem to be loads of theoretical replies but none of those replying actually said that what they were saying was from experience. When they start throwing in terms like the disk controller should you know that it is just a theoretical answer.

 

[hairlessupportmonkey]

Normally the reason for the slow down in performance is because the PC has no room left to cache to, to its constantly swapping between RAM and the HDD, and its rather slow at doing this, where I would think the same would apply with the SSD but it would work much faster due to quick read / write speeds, and no mechanical lag with the drive heads going mad.

the best way to prove it is do some tests.

get a std HDD, and an SSD, fill the one drive, clone it to the SSD and see what the difference is.

ACSS - SME
General Geek

 

[Triton101]

specs are all different for different generations of drivers, some are better than others.

but the performance hit on all is noticeable, but still good. the garbage collection and TRIM options help to speed up the drives, but the MAJOR reason to keep some space empty on the drive is write operations, not for reading.

so if you check out the speed differences, some drives take a beating (older ones) and new ones that support TRIM don't as much.

but if you fill up a drive, it's fine, so long as it's not your Boot drive (root, main OS drive) (for the reasons mentioned in above posts) you just can't save to it anymore....

just remember, READ operations, rarely, get affected, it's always the WRITE operations....

__________________________________________________________
Find a job you love and you'll never work a day in your life. - Confucius

 

[cdogg]

Another key point is fragmentation. The closer a hard drive is to being full, the more likely new data added to the drive or existing data being moved on the drive will become fragmented. The combination of high fragmentation and low free space hurts both read and write operations on a standard hard drive. SSD's, on the other hand, are not affected by either.

As hairlessupportmonkey points out, the cache or page file on the system drive could become a factor. However, I wouldn't consider it important. Cache issues negatively impact both types of drives. Taking it into consideration turns the discussion into what version of Windows you're using, page file settings, etc., introducing way too many factors and taking the discussion way beyond the scope of "HDD vs. SDD".

-Carl
"The glass is neither half-full nor half-empty: it's twice as big as it needs to be."

[tab][navy]For this site's posting policies, click [/navy]here.

 

[xwb]

What I'm really interested in

1) Have you experienced this
2) What was it like

and rclarke has given me the answer.

There are lots of theories that people read about and talk about. I did a lot of that 35 years ago on my CS course: purely theoretical. It isn't anything new. I just want to know that it is like in practice: not many people have had that experience: an SSD that is almost full.

There is a brilliant theory that increasing the cache can cause more thrashing - Belady's anomaly. The example that is given proves it but how often do you have a slow down and are able to say yes: that is Belady's anomaly

 

[cdogg]

1) No, but...

2) I am using small 80GB Intel 320 SSD's on more than 20 workstations where I work. This discussion got me interested, so on one workstation that had less than 5 GB free, I intentionally filled the rest of the drive up with misc files to the point where there was only about 100 MB of space left on the drive. I benchmarked it before and after doing that. I also compared it to another workstation that had 30 GB free with the same hardware/software configuration.

Turns out that boot time, launching applications, and shutdown time were nearly identical (within 2%) before and after I made the change. It was also about 5% faster than the other workstation in boot time, 2% faster to open applications, and 2% slower to shutdown -- not enough to conclude that filling the drive had any impact.



-Carl
"The glass is neither half-full nor half-empty: it's twice as big as it needs to be."

[tab][navy]For this site's posting policies, click [/navy]here.