Ssd Required Size

[esbkk]

An IT engineer, who I believed really knew “his stuff” told me once that a HDD should always be about 50% empty to work efficiently and I have always followed this advice.

The idea of a SSD for my OS & applications appeals to me. Changing to a SSD, would the same rule apply? My OS & applications amounts to approx. 42GB and an Intel 80GB should therefore be large enough.

In addition, I plan to have a second HDD - WD 1TB Black Caviar – for Media & Scratch files and a 500GB HDD solely for backups.

Any comments or suggestions would be greatly appreciated.

[dave_boo]

There is some validity in what the engineer told you. Basically what it did was confine the data to the tracks that are the fastest and this provides a smoother experience.

If you're going to use an SSD there is no reason to worry about this problem. Obviously SSDs don't use platters so there is no rotational latency to worry about--the controller can access any block just as efficiently as the next. There's some penalty for running a drive without TRIM support and adding/removing a lot of files but Intel does a really good job of preventing that problem.

Another thing to consider is to partition that 1 TB into to parts; keep the first partition for your scratch/swap drive (if you have decent amount of RAM and a good OS you won't need a whole bunch) and just dump your media on to the rest of space since I highly doubt you'll notice even 40 MB/s difference between areas of the disk when you're watching a sub 1 MB/s video.....

[esbkk]

There is some validity in what the engineer told you. Basically what it did was confine the data to the tracks that are the fastest and this provides a smoother experience.

If you're going to use an SSD there is no reason to worry about this problem. Obviously SSDs don't use platters so there is no rotational latency to worry about--the controller can access any block just as efficiently as the next. There's some penalty for running a drive without TRIM support and adding/removing a lot of files but Intel does a really good job of preventing that problem.

Another thing to consider is to partition that 1 TB into to parts; keep the first partition for your scratch/swap drive (if you have decent amount of RAM and a good OS you won't need a whole bunch) and just dump your media on to the rest of space since I highly doubt you'll notice even 40 MB/s difference between areas of the disk when you're watching a sub 1 MB/s video.....

I am using WIN7 Ultimate 64-bit as the OS and have 8GB of ram – all the MB will take.

Is there such a thing as a perfect arrangement of HDD’s?

Adobe PS suggests using drive C: (or the one with the OS) as the scratch drive, whereas Adobe Audition suggests using the “largest and emptiest” drive available.

Would adding another drive as a scratch drive improve the whole configuration?

[lomatopo]

A lot of people are recommending a minimum 120 GB for a "System" HDD.

There have been several SSD threads here recently, lots of good info. in those.

Some of these SSD's suffer from pretty significant failure rates.

A recent SSD round-up/review.

I went for a WD 'Raptor (10,000 RPM) 150 GB HDD for a system HDD on a recent build. The performance is excellent for my modest requirements. This HDD was ~ 30% of the cost of an equivalent SSD.

[prism]

I'm using the Intel 80 gig SSD as a boot drive and a seagate 1TB HDD for storage. 80 gigs is fine for the OS and a few apps., and yes...the thing flies! WEI score 7.6. The Intel also supports TRIM. Do your research on SSDs first before you build your rig. They do need some TLC but they won't lose their performance with the right settings.

[dave_boo]

I am using WIN7 Ultimate 64-bit as the OS and have 8GB of ram – all the MB will take.

Is there such a thing as a perfect arrangement of HDD's?

Adobe PS suggests using drive C: (or the one with the OS) as the scratch drive, whereas Adobe Audition suggests using the "largest and emptiest" drive available.

Would adding another drive as a scratch drive improve the whole configuration?

If you're going to use your SSD as the boot drive I'd definitely recommend putting it as the C:\ drive and your scratch drive on your D:\ drive to minimise writes/erases on the SSD. I would (perhaps erroneously) that you'll be working with files big enough that they're going to be more CPU constrained than disk subsystem limited and why take the chance of 'wearing' out your investment for what's sure to be no gain.

I also think that adding another drive would improve nothing except for adding to total heat, energy consumption, and e-penis bragging.....

[welo]

Limited free space on a partition will

• increase write times - larger files cannot be written in one go but will be split into fragments. This applies to any heavily fragmented file system, however
  
• a defragmentation process will take longer on partitions with only little empty space
  

15-30% of free space are the numbers that I have heard related to this question.

Maybe dave_boo is right that the IT engineer recommended 50% because of the performance of traditional disk drives declining from the 'start' to the 'end' (outer to inner tracks), often significantly, cutting average transfer rates in half.

However, this could easily be avoided by using partitioning strategies. You could even create a single partition that covers only half of the harddisk and not use the second half at all. But in typical home user setups you can always use the 'slower' half of the drive for less important data (data archive, mp3 collection etc), no need to waste it.

For SSD vs. 10000rpm drives google 'SSD vs raptor' and save a view hours for a good read

If money is not the issue then the SSD is the better performing solution I guess.

Anybody knows how defragmentation relates to SSD drives?

[welo]

Having done a quick google research I wonder how relevant the alleged limited life-time of SSDs related to write operations really is...

Have a read here

http://www.storagesearch.com/ssdmyths-endurance.html

what the article basically says is that 'write endurance is not a factor you should be worrying about', meaning that you don't need to worry about doing 'too much writing' to your solid-state drive. And the article writes about usage of SSDs in professional server environments!

From what I understand it all boils down to 'wear leveling' and how effect it is. I further understand that over the life time of a SSD, wear leveling can actually decrease performance if not using TRIM (source: Solid-state drive - Wikipedia, the free encyclopedia

I am still confused though, is this article unbiased or just a marketing piece for promoting SSDs?

Some quotes from the article

The way that SSD oems deal with the management of write endurance internally within their products varies but they all have the common theme of scoring how many times a block of memory has been written to, and then reallocating physical blocks to logical blocks dynamically and transparently to spread the load across the whole disk. In a well designed flash SSD you would have to write to the whole disk the endurance number of cycles to be in danger.

How long have you got before the disk is trashed?

[...]

Write endurance rating: 2 million cycles. (The typical range today for flash SSDs is from 1 to 5 million. The technology trend has been for this to get better.)

[...]

2 million (write endurance*) x 64G (capacity) divided by 80M bytes/sec (ideal write speed assuming writing in large blocks) gives the endurance limited life in seconds.

That's a meaningless number - which needs to be divided by seconds in an hour, hours in a day etc etc to give...

The end result is 51 years!

*We assume perfect wear leveling which means we need to fill the disk 2 million times to get to the write endurance limit.

[nikster]

Hard disks get slower as they fill up, that's correct.

SSDs don't have this problem. However, SSDs have other problems where the performance degrades over time. In some cases, within a very short period of time. If you go with an Intel SSD you should be fine. I wouldn't recommend any other brand. For the fastest (but expensive) SSD out there, see the OWC Mercury Extreme SSD - it saves 20% of capacity for performance tuning and in one test shows zero degradation over time. Other SSDs in that same long run test get as slow as hard disks!

I have the Intel X-25M 80GB for OS X as my main drive and replaced my DVD drive with a 500GB HD for storage. The SSD is very fast, no doubt, but it doesn't quite deliver its maximum speed at all times. I don't think TRIM matters all that much - for us end users it's just one way to keep SSDs running well, but since it requires user intervention I don't think that can be the solution. The solution is something like the OWC mercury extreme, a self contained unit, that contains everything necessary to keep up performance. I don't really care how they do it as long as it works.

I expect there to be vast improvements on SSDs coming. The field is evolving fast.

Edit: In hindsight I think I'd go with 160GB+ next time. Yeah the disk is just for the OS and apps but many apps love to put lots of support or media files somewhere within the system folders. On OS X I can symlink these off to the HD but even so it would just be more convenient to not have to do this.

Edited June 25, 2010 by nikster

[Jimmyd]

I move my user folders (Contacts, Desktop, My Documents, etc.) off of my OS drive, leaving the drive for just the OS and Programs. Right now my Windows 7 x64 partition has 25.6 gigs on it.

I was thinking of getting an Intel 40 GB SSD as my OS drive, but this thread has me worried.

[welo]

Why does TRIM require user intervention?

What other problems do SSDs have that degrade performance over time?

Does TRIM work on Windows 7 out-of-the-box and reliable? - I found contradicting statements. Anybody knows more?

TRIM seems VERY recommended because it solves important problems with SSDs, at least that's what I understand. Namely slow writes and inefficient wear leveling.

In SSDs, a write operation can be done on the page-level, but due to hardware limitations, erase commands (which are inherently slower) always affect entire blocks. As a result, writing data to SSD media is very fast as long as empty pages can be used, but slows down considerably once previously written pages need to be overwritten.

[...]

A TRIM command allows an operating system to inform a solid-state drive which data blocks, such as those belonging to a deleted file or affected by a format command, are no longer considered in use and can be wiped internally.

source: http://en.wikipedia.org/wiki/TRIM

TRIM basically allows the SSD to manage its cells more efficiently, therefore lessening the risk of slow writes due to management overhead.

Edited June 25, 2010 by welo

[welo]

I move my user folders (Contacts, Desktop, My Documents, etc.) off of my OS drive, leaving the drive for just the OS and Programs. Right now my Windows 7 x64 partition has 25.6 gigs on it.

I was thinking of getting an Intel 40 GB SSD as my OS drive, but this thread has me worried.

Moving the data files to a different disk is a standard procedure I apply, even on my non-SSD system. It's easy enough with Windows XP, haven't found a clear strategy on Windows 7 yet, just pointed the 'documents' Library to a different folder leaving the Users/../My Documents folder in place.

It seems that besides TRIM another strategy is to provide additional GBs of storage internally (not reported to the OS) to optimize writes - just as nikster mentioned. MS writes (back in May 2009) that enterprise SSDs reserve up to 50% of storage for this purpose. The article provides a pretty good write-up on these and other technical aspects of SSDs: http://blogs.msdn.com/b/e7/archive/2009/05/05/support-and-q-a-for-solid-state-drives-and.aspx, I'm just not so sure how reliable some statements are on real world impact.

Not sure that cheap consumer drives do this as well, surely nothing close to 50% if any at all.

On a too small drive you might be tempted to fill up the drive too much and run into performance degradation over time. If you go for a small drive I'd assume that proper TRIM support is even more essential.

I further assume that TRIM plus enough empty space will also allow the SSD to avoid write bottlenecks. It would be interesting to know if partitioning the drive to use only maybe 80% of the capacity would be a viable strategy as well.

But this is just speculation based on a view technical aspects I've read.

I guess it is far more interesting what actually happens in real world scenarios. Maybe somebody can shed some light on it.

welo

[prism]

Why does TRIM require user intervention?

What other problems do SSDs have that degrade performance over time?

Does TRIM work on Windows 7 out-of-the-box and reliable? - I found contradicting statements. Anybody knows more?

TRIM seems VERY recommended because it solves important problems with SSDs, at least that's what I understand. Namely slow writes and inefficient wear leveling.

In SSDs, a write operation can be done on the page-level, but due to hardware limitations, erase commands (which are inherently slower) always affect entire blocks. As a result, writing data to SSD media is very fast as long as empty pages can be used, but slows down considerably once previously written pages need to be overwritten.

[...]

A TRIM command allows an operating system to inform a solid-state drive which data blocks, such as those belonging to a deleted file or affected by a format command, are no longer considered in use and can be wiped internally.

source: TRIM - Wikipedia, the free encyclopedia

TRIM basically allows the SSD to manage its cells more efficiently, therefore lessening the risk of slow writes due to management overhead.

TRIM requires minimal intervention. You must set the storage(controller) configuration to AHCI in the MB's BIOS. After that Windows 7 will enable TRIM when it detects the SSD. To check: run cmd as administrator, enter; fsutil behavior query disabledeletenotify, If the response is; DisableDeleteNotify = 0, TRIM is enabled.

I'd go with Intel SSDs,I've seen them around in Thailand. Their SSD Toolbox utility is great. Run the disk optimizer instead of Windows disk defragmenter. Never defragment a SSD, you'll just wear them down.

[welo]

Well, AFAIK switching to AHCI on a running system is far from trouble free. So better switch BEFORE installing the system.

I've also read that Trim on Windows 7 will only work with standard MS drivers and not with Intel's drivers. Does this info still apply today?

Seems old news. As of April 2010 Intel released TRIM enabled drivers.

[nikster]

I am a software engineer. Trim is something the ssd should do and the os should not have to know anything about it. The os should just see a storage unit.

More modern ssds have garbage collection and other technology built in such that they just work. And that's the way forward.

Having the operating system deal with such things is at best a short term hack.

[welo]

The problem is that the storage device (SSD) does not 'know' about the file system, because it does not know of the functional layers above, like which file system is used. Most file-system delete operations only flag the file as deleted but do not erase the data from the storage device simply because it's more effective (for the very same reason unerase tools are often able to recover deleted files). The storage device does not know that a certain data block is not in use any more, because no write operation to that data block has taken place.

TRIM is an addition to the ATA protocol to report that missing bit of information to the storage unit during write or format operations.

Assuming you already knew this (it's basically a write up of the wikipedia article on TRIM), I wonder why you would consider garbage collection by the SSD the more proper way of doing things.

It might provide a cleaner separation between the two layers (file system and storage system), but is most likely a lot less efficient.

Thinking about it I wonder how this could even be done without the SSD knowing about the file system structure - and there the 'cleaner separation' goes...

Don't get me wrong, I am Java programmer and I love Garbage Collection!!

peace,

welo

[ArtfulD]

How to change IDE to AHCI on a pre-installed system...

Its easy when you know how!

http://support.microsoft.com/kb/922976

I had to do it myself a week ago...

[nikster]

The problem is that the storage device (SSD) does not 'know' about the file system, because it does not know of the functional layers above, like which file system is used. Most file-system delete operations only flag the file as deleted but do not erase the data from the storage device simply because it's more effective (for the very same reason unerase tools are often able to recover deleted files). The storage device does not know that a certain data block is not in use any more, because no write operation to that data block has taken place.

TRIM is an addition to the ATA protocol to report that missing bit of information to the storage unit during write or format operations.

Assuming you already knew this (it's basically a write up of the wikipedia article on TRIM), I wonder why you would consider garbage collection by the SSD the more proper way of doing things.

It might provide a cleaner separation between the two layers (file system and storage system), but is most likely a lot less efficient.

Thinking about it I wonder how this could even be done without the SSD knowing about the file system structure - and there the 'cleaner separation' goes...

Don't get me wrong, I am Java programmer and I love Garbage Collection!!

peace,

welo

By TRIM I meant tools like those released by intel which "run TRIM" on demand, sort of like a defragmenter. I just think that's stupid. If you say trim is just an additional ata command, which was omitted in previous implementations simply because it was irrelevant for hard disks then I am all for it. Ssds can't and shouldn't know about file systems, clearly.

[welo]

OK, I see. I didn't know about those software tools.

Good (technical) reads on the topic:

http://blogs.msdn.com/b/e7/archive/2009/05/05/support-and-q-a-for-solid-state-drives-and.aspx (there is a short section on TRIM)

http://en.wikipedia.org/wiki/TRIM

welo