Samsung 840 Pro or Intel S3500?

[Rhinox]

I need small storage for ~10VMs on my ESXi-server. Right now I need about 150GB, with perspective of up to 200GB by the end of this year. R/W ratio? Anything between 2:1 and 5:1 (hard to guess). Controller is M5016. I narrowed down my options to these 2 for about the same price (if there is some better option I can add it, but I'd like to stick with LSI-supported SSDs):

1) 2x Samsung 840 Pro / 512 GB for raid1 (2x ~370€ here)
2) or 2x Intel S3500 / 300 GB for raid1 (2x ~300€ here)

BTW I have selected bigger 840/pro drives because I have read on this forum at least ~30% must be reserved for OP, so what remains then is 358 GB (out of 512). S3500 come with OP already, I think ~7%. So true "usefull" capacity is quite comparable.

So what do you think: Which one is better?

840pro:
+ higher IOPS and write-speed (at least according to specification)
+ better price_per_GB (not accounting for OP-space) but more expensive

Intel S3500:
+ entry-level server SSD with capacitor (power-fail protection)
+ costs less (but price_per_GB is worse)

For some time I considered also raid10 with smaller drives for about the same price (4x 840pro/256GB or 4x S3500/160GB), but I'd like to keep my options open for future upgrade to raid10 without expander, so for now I want to stick with raid1.

 

[dba]

Both the 840 Pro and the S3500 are great drives, and you summarized it well: The Samsung wins for performance, but the Intel has power fail protection. In the configuration you are looking at, the highly over provisioned Samsung will also have dramatically better endurance than the Intel. See this for some disappointing information about S3500 endurance: Results: Write Endurance - The SSD DC S3500 Review: Intel's 6 Gb/s Controller And 20 nm NAND

If it were me looking for a VM storage solution, I'd go for the Samsung if my RAID card was battery backed, and the Intel if not. Actually, for a production system where the VMs will be busy and important, I'd dig through the couch cushions in an attempt to afford an S3700 instead.

 

[Rhinox]

Well, no matter how long and deep I dig, I can not find funds for 3700. With ~2€/GB it is expensive as hell, and 200GB raw unformated capacity would on the edge even right now (mirthless perspective of buying two more just a month or two later). But I can consider 3rd option:

3) 2x Samsung SM843T / 240 GB, (2x ~240€)

It is said to have 7% over-provisioning already. I'm not sure if it is enough (if 840/pro needs 25-30%) and if user can change it at all. But compared to S3500, SM843T has higher writing speed (370 vs 315MB), higher 4k-IOPS (98k/15k vs 75k/9k), and higher TBW (960 TB vs 170 TB). With ~200GB formated capacity it would be enough right now, half year later I would buy two more and change it from raid1 to raid10.

Low write-endurance of S3500 really scared me! SM843T/240GB has TBW 5PB/960TB (best/worst), that is more than 2x complete random overwrites every day (500GB) for 5 years (warranty time). Even with write-amplification factor 5:1 it is still more than enough for me...

 

[Jeggs101]

Any reason not to get the Crucial m500? I've seen tons of those in datacenters lately.

 

[dba]

SM843T = 840 Pro + power loss protection + eMLC = Excellent. If you can find them, go for it. Be sure that you are getting the SM843T and not SM843 or PM843T.

Even with the eMLC, I'd format them to 200GB to leave more OP in order to get more IOPS and more consistent latency - that's what I do with the 840 Pros and the 830s. No SSDs "need" that much OP, it's just that you can get a consumer-ish SSDs to perform surprisingly like Enterprise SSDs if you allow them more OP. I note that most Enterprise SSDs come in capacities like "100GB", "200GB", and "400GB", while actually containing about the same quantity of NAND as as a consumer 128/256/512GB drives.

 

[Rhinox]

Any reason not to get the Crucial m500? I've seen tons of those in datacenters lately.

I thought about M500 too, but I see four problems:

1. 120, 240 and even 480GB versions have only 256MB cache (only 960GB has 1GB-cache)
2. only 3 years warranty
3. not on LSI-supported list
4. Low TBW (total bytes written) value. Datasheet says 72TB, no info about which version is it for (I suppose 480GB) and if it is sequential/random (I think sequential). You see S3500 has much higher TBW, and SM843T crazy much higher.

M500 seems to me to be typical consumer SSD. Excelent price_per_GB, very good for desktop, but I think not so good for server. But I might be wrong...

 

[StephD]

How about Seagate 600 Pro SSD 240GB ?

 

[mrkrad]

They are all about the same, the 840 pro is not supported by LSI and requires a lot of work to get working from megascu/megaraid controllers out of the box.

S3500- are they on the list as well

Seagate 600 pro ssd, they have 30% OP as well - probably similar to the Samsung 840 pro in performance.

Fact is you have to give up something to keep speed up as well, and TRIM in its current form doesn't allow NCQ to happen so that will never work out.

 

[dba]

They are all about the same, the 840 pro is not supported by LSI and requires a lot of work to get working from megascu/megaraid controllers out of the box.

S3500- are they on the list as well

Seagate 600 pro ssd, they have 30% OP as well - probably similar to the Samsung 840 pro in performance.

Fact is you have to give up something to keep speed up as well, and TRIM in its current form doesn't allow NCQ to happen so that will never work out.

The Samsung SMT and 840 Pro SSDs are now on the LSI compatibility list for the HBA's, the 92xx RAID cards, and the new 93xx RAID cards. See: Interoperability & Compatibility

 

[OBasel]

I saw the M500 on there too: http://www.lsi.com/downloads/Public...les/MegaRAID_SAS3_934x_Compatibility_List.pdf

Really perplexing is that it only lists the M500 960 GB on the matrix not the smaller capacities.

 

[dba]

I saw the M500 on there too: http://www.lsi.com/downloads/Public...les/MegaRAID_SAS3_934x_Compatibility_List.pdf

Really perplexing is that it only lists the M500 960 GB on the matrix not the smaller capacities.

I would take it to mean that any of the M500 capacities are going to work properly. That said, to me it's only the 960GB of the drive that is interesting: Consumer priced but with Enterprise-like power fail protection in a large capacity drive. These would make good read-mostly bulk storage drives - as in a high IOPS NAS.

 

[StephD]

All M500 seem to feature power loss protection. I will probably get one of these myself.

 

[nitrobass24]

Does the M500 have an built-in OP, or do you need to do it mannually like on the Samsung Evos?

 

[dba]

Does the M500 have an built-in OP, or do you need to do it mannually like on the Samsung Evos?

Actually, all SSDs have a considerable amount of built-in OP. The Samsung EVO actually has more OP, by default, than the 840 Pro.

It just turns out that adding even more OP leads to higher sustained IOPS and better reliability, especially when we're talking about consumer-grade drives. In fact, formatting a 240/256GB consumer-grade drive down to 200GB goes a long way toward making it perform like a 200GB Enterprise drive.

Check out this great article: http://www.anandtech.com/show/6489/playing-with-op which benchmarks various performance parameters as a function of over-provisioning percentages.

In the graphs, click on the Intel S3700 200GB button and then the buttons for the various consumer-grade drives formatted to 192GB. They are oh so close.

 

[Rhinox]

Actually, all SSDs have a considerable amount of built-in OP. The Samsung EVO actually has more OP, by default, than the 840 Pro...

I'm not sure it is always true. The first time I ran Samsung Magician it said my new 840Pro had zero OP and recommended to set it to 20%. If drive is marketed as 240GB or 480, it sure does have at least some OP (240/256, 480/512). But I'm not sure how it is if drive exposes its full capacity (256, 512, etc)...

 

[dba]

I'm not sure it is always true. The first time I ran Samsung Magician it said my new 840Pro had zero OP and recommended to set it to 20%. If drive is marketed as 240GB or 480, it sure does have at least some OP (240/256, 480/512). But I'm not sure how it is if drive exposes its full capacity (256, 512, etc)...

The 840 Pro defaults to 7% OP - at least in my version. If there is an option to set it to less, I really don't recommend it.

 

[Rhinox]

Well, I have found SM843T/480GB here (EU) for 400€, that's merely 8% more than 840Pro/512 (370€) and this solved my dilema. No more reason to go 840Pro-way, and even if I format SM843T to 400GB, I'll still have plenty of space for at least a few years. My thanks go to all who contributed with tips and opinions...

(of course S3700/400GB is better, but it should be, when it costs double so much!

 

[Patrick]

Great find! Price wise I would have done the same thing.

 

[ChrisRam]

2x 840 Pro 512GB drives will be fine for what you are doing. Personally I would stay away from IMFT 20nm, the latency is too high. I would also stay away from 840 EVO for what you are doing, once you get past Turbo Write the write performance drops rapidly.

Last but not least, SSDs read and write slower as the flash holds more data. Larger drives can hold more data but they also remain faster for longer. A 512GB SSD with 128GB of data on it will perform faster than the same model, but 256GB capacity, with 128GB of data on it.

 

[mrkrad]

I've had pretty good luck with the 512gb samsung 840 pro - @ 384gb usable each. It's not a lot but it is stable and doesn't seem to throw any esxi latency warnings anymore.