Trim on half a SSD, how will this work?

[Rifter]

So im going to be buying a SSD on boxing day/week. Im going to spend $200 on it and will buy whatever i can get for the best deal, a vertex 2 or intel G2 or whatever other brand is a good deal.

I dual boot linux and windows, my linux supports trim but vista does not. The drive will be split up with a 20GB partition for linux and the rest for windows. Am i going to run into any issue with some of my SSD being trimmed and the other part not?

Will this mean windows will show more slowdown and linux will stay fast?

Am i just overthinking this and once i get blown out of my seat by the blazing speed of the SSD i wont even remember anandtech exists so it wont matter?

 

[Nothinman]

Will this mean windows will show more slowdown and linux will stay fast?

Most likely this. The Vista partition will rely on whatever garbage collection the firmware can do while Linux will trim pages as necessary.

 

[taltamir]

Will this mean windows will show more slowdown and linux will stay fast?

actually that is not correct. You will have equal speed in both. You would be able to trigger a read-erase-modify-write cycle with both.

Wear leveling means that the data is shuffled around and is not where the OS/FS think it is. The FS partition might be limited to the first 20GB of the drive, but wear leveling will actually write it all over the drive. TRIM notifies the controller when data is erased, so that this data is no longer preserved by the drive when it needs to shuffle. Ideally it will even have enough free space such that it can always write to empty sectors without read-erase-modify-write.

I am not sure of the exact amount of performance you will lose (its not necessarily linear) but it stands to reason that it will be between that of fully TRIMed and no TRIM at all drive. But don't worry about it, even without any TRIM modern SSDs are very very fast compared to spindle drives.

 

[Rifter]

thanks guys.

One more question, lets say i find a screaming deal on 2 smaller drives. Would i be better of raiding them together in RAID 0 without trim but twice the performance or running them one for linux and one for windows with the windows drive not having trim and the linux drive having it?

 

[taltamir]

It is arguable which is better. I personally prefer one bigger drive with TRIM but there are valid arguments for both.

 

[Rifter]

It is arguable which is better. I personally prefer one bigger drive with TRIM but there are valid arguments for both.

I would prefer a bigger drive as well but i dont know whats ging to be on sale on boxing day. If it works out to be the same price ill get the one drive but if i can get more capacity for the money or the same capacity cheaper ill probably go with the two drives.

Do you know if they can add trim to raid through software or if thats going to require a whole new controller and thus new SSD's?

 

[aviat72]

This is what Anand had to say about SSD RAID.
http://www.anandtech.com/show/3618/intel-x25v-in-raid0-faster-than-x25m-g2-for-250



The performance is mind boggling. It compares with the performance of the latest SSDs with the latest/greatest Sandforce
http://thessdreview.com/latest-buzz...date-confirmed-great-news-for-new-ssd-buyers/

Here are some more up to date results of using RAID-0 on SSDs
http://thessdreview.com/our-reviews/raid0-the-ssd-simple-to-build-and-lightning-fast/


I actually ordered two X25-V 40GBs from NewEgg today. Will be using software RAID0 on them. They are $70 after rebate there. Once something better comes up the 40GBs will serve as boot disks on other desktops at home.

Of course there is this issue of no TRIM with RAID.

 

[taltamir]

a single x25-V 40GB is a lot slower than an x25-M 80GB. This would be better implemented in a x25-m 80GB vs 160GB (where the 160GB is faster, but a little faster instead of a lot).
This is because the -v is actually 5 channel while the rest are 10 channel.

There is also concern of write amplification with trim, and using 2 drives in raid0 means either paying more for a good controller, or risking losing the array to any number of flaws in implementation of cheap mobo ones (ex: resetting the cmos makes it lose the array, etc).

Essentially what the controllers do inside the drive is "more than raid0", it writes in parallel, but doesn't suffer most of the drawbacks of raid0.

If you want to raid0 SSDs, for best results use more then 2 drives.
http://www.anandtech.com/show/2968/...30gb-ssdnow-v-series-battle-of-the-125-ssds/5
As you can see, the 40GB X25-V has exactly half the sequential write performance and 70% the sequential read performance of the 80GB X25-M.
X25-M 80GB (w/TRIM):
Seq Write: 1x
Seq Read: 1x
X25-V 40GB (w/TRIM):
Seq Write: 0.5x
Seq Read: 0.7x

Take that and multiply by 0.65 (to account for speed loss due to lack of trim):
X25-V 40GB (no TRIM):
Seq Write: 0.325x
Seq Read: 0.455x

Since raid0 has so little overhead it essentially multiplies sequential read/write by the number of drives, you would get:
X25-V 40GB (no TRIM) RAID0 of 2 drives:
Seq Write: 0.65x
Seq Read: 0.91x

X25-V 40GB (no TRIM) RAID0 of 3 drives:
Seq Write: 0.975x
Seq Read: 1.365x

X25-V 40GB (no TRIM) RAID0 of 4 drives:
Seq Write: 1.3x
Seq Read: 1.82x

As you can see, this is clearly not worth it until 4+ drives. However, since X25-M 80GB and 160GB are within only a percent or two of each other, then it hurts a lot less, and a RAID0 array of those can sometimes be justified.

 

[Rifter]

I would be backing up the array, as anyone running ANY form of raid should unless they like playing with fire.

I would be using the onboard raid on a intel ICH10R, more than enough for a simple raid 0 array.

Like i said im going for one drive but we will see what happens, i didnt realize the intel 40GB were gimped.

Are the lower sized sandforce drives also gimped?

 

[taltamir]

i didnt realize the intel 40GB were gimped.

Its right in their name. X25-V
V = Value
M = Mainstream
E = Enterprise

Performance is E > M > V
in ANY SSD the bigger the faster, but its not that big a difference and the intel performance difference isn't due to size.

As far as sandforce, they have a regular and an enterprise edition, and indeed the enterprise is better.

 

[Rifter]

Its right in their name. X25-V
V = Value
M = Mainstream
E = Enterprise

Performance is E > M > V
in ANY SSD the bigger the faster, but its not that big a difference and the inter performance difference isn't due to size.

As far as sandforce, they have a regular and an enterprise edition, and indeed the enterprise is better.

looks like i should be shooting for a 80GB intel then or a 120GB sandforce drive.

 

[Rifter]

Pulled the pin on the Intel 120GB and purchased windows 7 as well, so i will be fully trimmed!