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Intel SSDs in Raid0 - Long term use

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June 9, 2010 2:47:39 PM

This question is more practical than my previous ones on SSDs,

My budget is ~$450, and I've been told in many ways that Intel's SSDs are superior to those of any other manufacturer if you include price as well as performance in the mix. Since I'm still a noob, I'll accept this.

I'll need about 160Gb of space, so this leaves me with two options:

1x Intel X25-M 160Gb
2x Intel X25-M 80Gb in Raid0.

I know how fast SSDs can be when you pull them out of the box, but my question here is which of these two options will yield the highest speed after months of usage being, say, 70-80% full?

I am undecided because I have seen excellent performance scaling with SSDs in raid, but they don't support TRIM while in raid, so performance loss is inevitable... the issue is really if heavy usage will drag the performance of the array below the level of the 160Gb drive.

You might be inclined to reply with "it depends on how you use the drive", to which I will say the drive will be used for Windows 7, apps & games and will be used every day. Once the drive has started to fill up, writing to the drive will be done rarely, but will inevitably happen as windows writes every time you boot up. Some performance degradation may be inevitable so I am willing to format, secure erase & essentually "start over", every 6 months or so, so long as performance is restored.

Some side questions:

- Should I store windows on another drive? Does frequent windows loading degrade the performance of an SSD even with TRIM?
- Are there other options (other manufacturers: OCZ, patriot, etc.) wich I have overlooked, and have comparable speed and price?
- Will new SSD controllers come out in the near future that allow TRIM while the SSD is in an array?

Finally,

- A lot of these questions are vague, and might not have clear answers, so, what would you do in my place?

As always, I'll take any/all help I can get.

Thanks in advance (esp. submessa, he's been a great help)
a c 98 G Storage
June 9, 2010 10:48:55 PM

I'd stick with Intel. And as a boot drive. Why else buy a SSD to put Windows on a HDD?

To fully utilize TRIM, I'd get the 160GB, if that is what you truly need. It'll keeping the drive at "max performance." All that you want to watch for is getting close to full capacity, which you already commented on. You could always partion the drive to 80-85% of capacity if you are scared of gettiing close to full. The other 15-20% would be left unused & unformatted for "drive optimization."

What I suggest is using your current HDD for data/media/storage, and just use the SSD for OS and Program Files. This should minimize writes to the SSD, after the initial install. And, all your data/media will be safe if the SSD or OS crashes. See my set up below.

Yes, Windows will "write every time you boot up" but not that large of amount of data. IMHO: To fully get the speed out of a SSD, I left everything alone. Yes, things like pagefile and internet cache do "corrupt" the drive, but wouldn't you still want fast access to these files too? I did once post a comment on slow downs on boot ups, but it seems to have "recovered." Programs still launch like lightning! I LOVE IT!

We can only hope Intel (or Microsoft, or whomever) will come out with TRIM support for SSD in a RAID array (I do, my SSDs are in a RAID 0)!

sub mesa AND sminlal are great at SSD topics! :bounce: 
a b G Storage
June 10, 2010 12:53:36 AM

^About the swapfile: For most users/programs you do not need a swapfile anymore with above 4GB or RAM. Also, do realize that if you leave the swapfile a lone, it's essentially wasting about 6GB or so on the SSD, given the fact that swapfile isn't that needed I'd reduce the size or disable it. I've been running with out a swapfile,even on my CAD machines and it works fine.

As far as SSDs goes, Intel currently has the best track record in terms of reliability vs performance vs price. There are faster/better drives out there but long term isn't well proven on those SSDs just yet. As for RAID, given your budget, you wouldn't save much money compared to 2x 80GB drives. The X25-M G2 160 GB is @ $425 at newegg: http://www.newegg.com/product/product.aspx?Item=N82E168...

I'd get the 160GB and have the option to use TRIM.
Related resources
a c 98 G Storage
June 10, 2010 1:36:46 AM

^+1
June 10, 2010 1:57:30 AM

foscooter said:


To fully utilize TRIM, I'd get the 160GB, if that is what you truly need. It'll keeping the drive at "max performance." All that you want to watch for is getting close to full capacity, which you already commented on. You could always partion the drive to 80-85% of capacity if you are scared of gettiing close to full. The other 15-20% would be left unused & unformatted for "drive optimization."

...

We can only hope Intel (or Microsoft, or whomever) will come out with TRIM support for SSD in a RAID array (I do, my SSDs are in a RAID 0)!



Thanks for the advice. Very helpful indeed, but my main question goes unanswered.

You are actually the ideal person to answer it because you've got 2 40Gb Intel SSDs in Raid0 and by the sound of it, you're using them extensively, just how I intend to.

I'd like to know what the speed of your array is. My real issue here is that because the array doesn't support TRIM, the overall performance of the array will be, though use, degraded to below that of a single drive, in which case it makes no sense to have it in the first place and just go with the next drive up.

Most would consider the performance degradation that I mention undesriable. (Submessa has shown me benchmarks of a used SSD down to ~60% speed because of use), quite frankly I wouldn't mind this as even a single intel SSD is blazing fast. I reckon that if I get the two 80s and stripe them, I'll see and initial r/w of 450/140, of course that will come down significantly and if I were to run a benchmark I'd expect to eventually see wild fluctuations in speed. Forgive me for repeating myself here but I'd be fine if the reads stay above 225-250...

The main reason why I'm bringing this up is that I'd like to counter the X25's frankly abysmal write speeds. 100Mb/s (for the 160Gb version) is just too slow IMO for a drive that I'll spend $400+ on. I can get that from a velociraptor for a quarter of the price.

... one of the few cons to an intel SSD is the write speed. If I can increase it through raid while not loosing out too much through lack of TRIM, then it would make intel the obvious choice for my needs.

I might be asking too much, but I'd love to see a benchmark of your (or anyone's) *extensively used* SSD array. It would answer the bigger question of if RAID-ing SSDs for everyday use is worth it.
a b G Storage
June 10, 2010 2:26:29 AM

Given the obvious premium for the best SSDs e.g. Sandforce SF-1222,
I still think it's wiser to wait until the kinks are better resolved
and, in particular, until SATA/6G SSDs become the norm,
and affordable -- particularly for someone with your budget.

You must factor into your buying decisions the FACT
that SSD manufacturers are prone to report BEST CASE
performance, and they are hesitant to reveal the
degradation that all MLC SSDs will experience over time.

There are no lifetime warranties on any Nand Flash SSDs
that I've seen or read about.


And, you are required to ask your excellent questions because
simple answers are just not that easy to find!


You might want to consider 2 x "RAID Edition" ("RE") HDDs
from Western Digital:

http://www.wdc.com/en/products/productcatalog.asp?langu...

For practical reasons, a 5-year warranty comes in very handy
for our office: we always compute price per warranty year,
and the 5-year warranties always come out ahead on this metric.

We have 2 x WD7502ABYS configured in RAID 0 on one of our
workstation system partitions, and the remainder is a large data partition:
we're very pleased with the performance:

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Two of the smaller WD2502ABYS should provide comparable performance,
on average:

http://www.newegg.com/Product/Product.aspx?Item=N82E168...


Another interesting option is Hitachi's 2.5" 147GB 10,000 rpm SAS/6G HDD
with 64MB cache (a smart move on their part, imho):

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Bear in mind that SAS requires a SAS-compatible controller
either on the motherboard, or an expansion card, and this
SAS HDD also requires a 6G interface.

It's now very easy to adapt a 2.5" form factor to a 3.5" drive bay.


We also strongly disagree with those who argue that
RAID 0 is more prone to fail: we've experienced just
the opposite. And, if one of the 2 drives fails,
all data are lost and the failed HDD must be replaced,
which is exactly the same situation if the same data set
is on a single spindle ("same difference" :) 

You can always demote such a RAID 0 with rotating platters
to a dedicated data partition, e.g. archiving/backups, AFTER the
SSD market settles down and meets the current 6G standard.

At that point in time, the availability of SATA/6G SSDs
should put downward pressure on the prices of SATA/3G SSDs,
at least.

Also, chipsets should be more widely available with
native TRIM support for RAID arrays e.g. see AMD's 890FX.
That is another, good reason to wait for SSDs to mature
some more.


I hope this helps (yes, I know you SSD lovers may climb all over me:
fine! I encourage freedom of speech at all times.)


MRFS

a c 98 G Storage
June 10, 2010 6:17:05 PM

I'd love to give you "benchmarks" for my set up, but I have not idea how to do that! Anone?

Anyway, thru much discusion in THG, mainly with sub mesa and snimlal, this is how I set up my SSD RAID 0 array:

1) set up the array in BIOS (duh!)
2) installed WIndows 7, during which I partioned the RAID drives into 3 partions:
a) The Windows System Reserved 100MB partion that Win7 does on a fresh install.
b) The Windows partition/drive at 64GB. (80% of RAID array total drive size)
c) The remaining 16GB+/- as unallocated, unformatted partion. This was to combat the loss of TRIM for my SSD in a RAID array.
The SSD is supposed to use this area to self-optimize.
When I check to see is TRIM is "running" it is, but...

And yes, write speed are "low" but once to install the OS and programs, read is what really matters. It still only took me 16 minutes to install Windows 7 from DVD to ready to use. Then only 1 hour or so to install and tweak all my programs.

If you think you'll be running programs that will write alot, maybe you should go with HDD. For example, my data and media are all on my other RAID 0 array. It has all My Documents, Music, Pictures, Videos, and Downloads. Now these files get read and written over alot...

Once again Thank You, and Good Luck.
June 10, 2010 6:45:38 PM

SSDs only degrade write performance from being full. Read performance doesn't take any hits. This is because SSDs need to do a delete cycle and write cycle to replace information from used sections.

Most people use SSDs for boot drives which doesn't get much write action. However if you are shuffling information around with an SSD, then you would suffer more without the TRIM command.
June 11, 2010 7:42:49 PM

foscooter said:
I'd love to give you "benchmarks" for my set up, but I have not idea how to do that! Anone? .

If you are still willing, here's how:

- You'll need to install some benchmarking software. I'd go with "HD Tach" or "HD Tune", there are many out there, but they'll all give you the same basic data with a bit of variation
- Run a scan/benchmark of your SSDs in raid0.

What you'll get is an analysis of write speed/read speed/ access time + a load of other information at various points on your drive.

Here is an example.
... you must have seen these before.

I'm going to take a guess here and say that a single 40Gb intel SSD has speeds, according to newegg, of 170 Read and 35 write. I'm hoping that your raid array will have at least this, as that would make raid-ing worthwhile.

I still think it's wiser to wait until the kinks are better resolved
and, in particular, until SATA/6G SSDs become the norm,
and affordable -- particularly for someone with your budget. said:
I still think it's wiser to wait until the kinks are better resolved
and, in particular, until SATA/6G SSDs become the norm,
and affordable -- particularly for someone with your budget.


So far I've got an i7-930 with 6 gigs of gskill ram at 1600Mhz on an Asus P6X58D-E motherboard with a 9800GX2 video card, and I'm using a 1Tb Seagate Barracuda as my main drive. I think most people would agree, allong with the windows experience index, that the hard drive is my bottleneck.

I find my options are either an SSD boot disk for my OS and apps or a pair of VRs in raid0.

Although the raptors would give me more space and have faster write, they would cost the same and have a slower read and access time.

They are also loud, although that is a minor point.

There are plenty of reasons for and against, and quite frankly I still haven't 100% decided on anything.
a c 126 G Storage
June 11, 2010 8:51:18 PM

rofl_my_waffle said:
SSDs only degrade write performance from being full. Read performance doesn't take any hits.

Only true for simple first-gen SSDs that do not do write remapping.

This is the traditional way of how SSDs dealt with random writes: always do a slow read-erase-program cycle with high write amplification. Logical LBA = Physical LBA.

Newer SSDs like Intel do write remapping; they actually write small writes requests to a different location to where the Operating System thinks it is being stored. This way, it can avoid the slow and write-heavy read-erase-program cycle and writes to a free erase block without having to erase anything. This speeds up these random writes considerably, but it does require the SSD to keep track of the difference between how Windows thinks the data is stored, and how it is actually stored on the NAND flash; this is stored in the Mapping Table located in the HPA or Host Protected Area of the SSD.

Now the real clue: as this table gets fuller due to random writes, and fragmentation due all relocations begins lowering the available free erase blocks, you would also degrade your read performance as well. This can be seen already after a clean install of Windows; the parts where random writes or modifications have happened would show degraded read performance. This slight degradation is not possible to avoid on modern SSDs. It's a trade-off and generally makes sense, as SSDs are pretty fast in reading also. Here's how it would look like:



There is a lot more to it than the above, for example i haven't named that due to fragmentation fewer flash channels can be used in parallel; lowering performance. But this approaches my own understanding, and i'm reluctant to test and 'battle wear' my own precious Intel SSDs; which i really enjoy having. Plus i enjoy bragging about my 1234MB/s random read performance sometimes. ;) 

In this thread on another forum i discussed SSD performance degradation in more detail:
http://forums.anandtech.com/showthread.php?t=2076773
a c 98 G Storage
June 12, 2010 2:22:37 AM

I got some benchmarks! And after much ado, screenshots!

SSD = 2 x Intel X25-V 40GB in RAID 0
HDD = 2 x Seagate 7200.11 500GB in RAID 0
HDD-NR = 1 x Seagate 7200.12 1TB (no RAID!)

Test 1: Benchmark READ rate (can’t do writes test!)

SSD: Avg =246.3MB/s!!!




HDD: Avg = 151.0MB/s!




HDD-NR: Avg = 119.2MB/s




And results can vary. Ran it again, and look at the rise!!!

SSD: Avg = 305.4MB/s! Max = 437.0MB/s!

a c 98 G Storage
June 12, 2010 3:08:14 AM

Test 2: File Benchmark (read & write) This one is quite impressive!

SSD: Peaks at over 350MB/s reads, but steady at 50-80MB/s writes. This what Intel's SSDs do!




HDD: Peaks at over 150MB/s reads, but also at over 150MB/s writes!




HDD-NR: Peaks at over 100MB/s reads, but only over 75MB/s writes.



WOW, what a difference. RAID really boosts reads on both, but only helps writes on HDD! But then again, that is what SSD's do.

I can show more, or later if you'd like. This system has been running since 04/17/2010, when I did my last Windows install.

That was fun!
a c 98 G Storage
June 12, 2010 3:22:45 AM

Ok, this is is. I don't what to fill up this forum with my tests! I already got a warning. I'll be a good boy! :ange: 

Test 3: Random Access. Again SSD bombs everything else!

SSD = 2 x Intel X25-V 40GB in RAID 0:



HDD = 2 x Seagate 7200.11 500GB in RAID 0:



HDD-NR = Seagate 7200.12 1TB




My backup drive (non-RAID) beats my data/media drives (RAID 0)! Might have something to do with platter size.
June 14, 2010 3:18:25 PM

Wow. That is impressive. I wasn't expecting results like that from two 40Gb drives. It almost seems like you've doubled the performance of the two drives... The 80Gb has write speeds that are similar to yours, but you've doubled your read as well. An average of 300? Wow.

However, this seems to contradict what submessa said. There should have been a performance drop, just like in his screenshot - at least in the areas where your OS was installed.

So I feel compelled to ask both of you why this could be.

Submessa, can you explain these results?
Foscooter, is there any special utlilties you are using to keep your SSD array that fast? Is there any special measures you have taken to prevent "fragmentation" and the like?

And perhaps another question, how much of that 80Gb are you actively using?

I applaud submessa's 1.2Gb/s read SSD battery, but I feel compelled to ask, if you aren't going to use it, then what is the point?

The HDD array results seemed typical, good, matching speeds in both read and write.


a c 98 G Storage
June 15, 2010 2:44:57 AM

No special disk utilities! No "measures." Like I said before, I DID NOT do any of the "tips" for SSD use (i.e. move pagefile, turn off PreFetch, etc.).

My drive does take a "hit" in the first 8GB where my OS is.

As also stated before, the only thing I did, with help from sub mesa, is I partioned the drive as only 80%, in 3 partitions:

1). System Reserved - 100MB - Part of Windows 7 install (no drive letter)
2). Windows - 64GB - Drive C: 21.4GB used, 38.5GB Free Space
3). The remainder, 16GB +/-, as unallocated, unformated, unused (for disk self optimization)(no drive letter)

Here is what my system looks like in Disk Magagement:



BTW: My stripe size is 128KB (recommended by RAID setup).

P.S. After a second look, I guess I "moved" my pagefile to my D: drive. I forgot. But I have 6GB of memory, so it's probably never used, just allocated as 6148MB in Windows managed size.
June 16, 2010 2:02:30 PM

foscooter said:
No special disk utilities! No "measures." Like I said before, I DID NOT do any of the "tips" for SSD use (i.e. move pagefile, turn off PreFetch, etc.).

My drive does take a "hit" in the first 8GB where my OS is.

As also stated before, the only thing I did, with help from sub mesa, is I partioned the drive as only 80%, in 3 partitions:

1). System Reserved - 100MB - Part of Windows 7 install (no drive letter)
2). Windows - 64GB - Drive C: 21.4GB used, 38.5GB Free Space
3). The remainder, 16GB +/-, as unallocated, unformated, unused (for disk self optimization)(no drive letter)

Here is what my system looks like in Disk Magagement:

BTW: My stripe size is 128KB (recommended by RAID setup).

P.S. After a second look, I guess I "moved" my pagefile to my D: drive. I forgot. But I have 6GB of memory, so it's probably never used, just allocated as 6148MB in Windows managed size.


(I posted a reply before, this is an edit)

I notice you've got a spare, un-formatted partition, just as submessa recommends. It seems that if you reserve a spare partition, you will restore speed even if you are in an array and thus TRIM is not working.

So therefore it seems that if I get the twin 80Gb X25's and reserve 20% (32Gb) (although I could probably cut this down a bit), then I'll be able to get consistent results of, oh... 450 read/ 140 write despite windows being installed and the remainder of the drive being filled. Conversely if I get the 160Gb SSD, then I'd get 250 read/ 100 write even if I reserve 20% for the drive anyway.

I would also like to know if this works with other SSDs, (although I know that Intel's have ~7% reserved for just this purpose)

... and finally, it seems that with my budget I could potentially go for a 4x40Gb array - similar to Submessa's. Any thoughts?
July 1, 2010 1:21:31 PM

I question the use of RAID with SSD's for any reason. Redundant Array of Independent(Inexpensive) Disks was developed to overcome limitations of spinning disks with magnetic coatings. SSD's have none of these things. I plan to wait for Redundant Array of Independent Solid State Devices (RAISSD (raised)) or whatever the marketing guys name it.
a c 126 G Storage
July 1, 2010 1:41:29 PM

SSDs already use RAID0 or interleaving. For example, the Intel X25-M uses 10 parallel flash channels that could be explained as a 10-disk RAID0 array. Just like RAID arrays, you need multiple queue depth to use those 10 channels, or it will only use one.

This can be seen very clearly with AS SSD and CrystalDiskMark benchmarks, where the 4K random read scores show a major difference between single queue (20MB/s) and multiqueue (up to 200MB/s). Thus up to a 10x difference thanks to the interleaving/RAID0 in modern SSDs internally.

RAID0 could be compared with dual channel memory, SLI videocards and multicore processors; it doesn't help in all circumstances and depends greatly on the exact setup of how much performance increase it will bring; but it sure can help and all these concepts use parallel I/O as base for increasing performance. If you can do two things at once instead of one thing, that should mean it goes twice as fast. That principle can lead to very nice performance gains.

I should note that HDTune is less suitable for testing RAIDs and SSDs; generally i recommend CrystalDiskMark and AS SSD because these test on the filesystem and also test random I/O under various conditions. These benchmarks could also tell whether random I/O gets any faster due to the RAID.
a c 98 G Storage
July 1, 2010 10:30:28 PM

sub: got links to Crystal or AS SSD?

I tried Crystal but must have had the wrong one. Looked nothing like what I've seen.
!