What is the fastest SAS drive right now?

[thebeephaha]

Not looking to buy, my Raptors are fast enough for me but I am just curious to see how 15k SAS is holding up compared to solid state drives.

[alamone]

Probably the savvio 15k.2 and the cheetah 15k.7.
Prior to that, the savvio 15k.1 and the cheetah 15k.6, I believe.
Other manufacturer's 15k drives are probably pretty similar, though.

There's no datasheet for the cheetah 15k.7 yet, but for the savvio 15k.2:
STR = 122 to 162MB/sec
seek time = 4.9 ms

One problem is that SAS drives tend to be pretty low capacity;
the savvio 15k.2s only go from 73gb to 146gb, for example.
I think the cheetah 15k.7 goes up to 600GB, and the 15k.6 goes up to 450GB.

If you happen to have a SAS card, it might be worth picking up a few cheap ones
on ebay, but otherwise a velociraptor will probably suit most people's needs fine.

[thebeephaha]

I have a 73GB Savvio 10k.2 and it really isn't very fast, surprisingly.... a VR seems to be better for the money. But the 10k.2 series is getting to be a little older.

I was looking online and saw that Seagate's new 15k.7 looks nice or maybe a Hitachi Ultrastar 15k.

I am having a hard time finding benchmarks on them though.

[alamone]

They go a bit faster if you're able to dual-port them, as they can communicate over 2 channels for dual read/write. SATA is only 1 channel via half duplex, SAS is 2 channels full duplex.

[thebeephaha]

They go a bit faster if you're able to dual-port them, as they can communicate over 2 channels for dual read/write. SATA is only 1 channel via half duplex, SAS is 2 channels full duplex.

OK. I need more information on this!

So lets say I have two of those Savvio 10k.2 drives and RAID0 them, I would use 4 ports/channels to do it? I assume I need a special cable to connect it to my SAS controller? Or am I totally off base here.

Do I need special drives? I noticed on my Savvio drives there is a power connection, the data connection like on a normal SATA drive except they are connected in the middle but on top there is a mini data connection. Is this for the dual-port?

http://dl.getdropbox.com/u/14680/sas.jpg

[thebeephaha]

Was just looking, either I can get a cable like this to go from the dual SAS on the drive:

http://dl.getdropbox.com/u/14680/SAS-8282-2.jpg

But... instead of two SATA ports I need it to go to a SFF-8484 connector like this:

http://dl.getdropbox.com/u/14680/800px-SFF_8484_angled.jpg

Which I guess would be a SAS 29 Pin Dual Port to SFF-8484. Or could get this and us my existing SFF-8484 to four SATA?

http://dl.getdropbox.com/u/14680/SAS-Group.jpg

Anyone actually know about any of this? And if my Perc 5/i controller supports this feature?

[Syntax Error]

You need a special SAS cable to be able to connect your drive to your Perc 5/i.

[Neb]

As far as I have seen, dual porting has mostly been marketed as a redundancy feature first and foremost and performance second. I would like to see additional info on dual porting, as it doesn't seem very well documented aside from redundancy.

[thebeephaha]

Hm, well either way that is a cool feature I didn't even know about.

Still though, does anyone know which drives are the leaders in SAS? Any good benches I can look at to cure my curiosity?

[figgie]

More than likely similair performance

Remember, SAS came from the server world, they need "enough" for the budget at hand.

Any of the 15k drives will be quite fast.

[alamone]

Your RAID card has to support multipathing to take advantage of the performance increase of dual ports.

According to LSI's spiel, you get a performance increase of 40% in their newest Megaraid driver. If I recall correctly, the Dell PERC cards are based on LSI ROC, so you might be able to use the Megaraid driver with it.

http://www.lsi.com/DistributionSystem/AssetDocument/ESG_MR_Release35_WP_120408.pdf

Adaptec has a similar spiel whitepaper on their website.

Just FYI, I went from a single port raid0 savvio to a dual port raid0 savvio and my benchmarks improved, and it does feel faster. This is on an Adaptec 51645 card.

[nitrobass24]

Note on Dual Porting:

First off your controller must support multipath's
Secondly it is only for redundancy as far as I can tell just because a drive can only be reading or writing data at any given moment. The drive cannot be doing both simultaneously.

Perc 5/i may be able to pull it off download the latest megariad drivers and megaraid utility and see if there is an option for it. I have not ever seen it done on a Perc 5/i but that doesnt mean that it cannot be done.

[alamone]

It's only limited to redundancy if that's the way the RAID stack is configured, which was the case for the Megaraid driver until the 3.5 release. I believe the Adaptec drivers always took advantage of multipathing for performance.

While the drive might physically be able to only read/write one thing at a time, it can still accept multiple commands from the dual ports and service them accordingly. Thus, you get IOPs improvements from dual porting, if not bandwidth improvements, since you're still limited by the RPMs of the disk and the areal density.

If I understand correctly, for performance multipathing:
SATA: One read OR one write request, single port only
SAS: One read AND write request PER port, up to 2 ports

[thebeephaha]

That is interesting. Any idea on possible cable solutions? Thats the biggest thing for me. I'm willing to buy and be the guinea pig, just need to find the right stuff.

[Ockie]

SAS drives will not be able to keep up with SSD's (especially if you look at SSD advancements), however, they are a little more cost effective still considering their proven heritage and their solid performance. SSD's are still more or less a niche application where SAS has proven itself in the server arena.

The Cheetah 15.7's are going to be your fastest SAS drives out there.


As for the comment made earlier, you do get large SAS drives, all the way up to 1TB (ported SAS).

[Pkirk618]

Hey Ocki, what's the deal w/SSDs formatting issues when they reach capacity...or something along those lines? MaxPC has an article (past article) speaking of the pitfalls of SSD's, though they praise them more than anything. If you're not familiar of the issue above, do you have any impressions, comments both pros/cons on these drives.

I ask because I considered intels latest, not the SLC extreme but the MLC, cheaper version for my OS drive. I currently have a raptor sure but lets pretend money wasn't an issue (and Intels extreme wasn't available).

[Ockie]

Hey Ocki, what's the deal w/SSDs formatting issues when they reach capacity...or something along those lines? MaxPC has an article (past article) speaking of the pitfalls of SSD's, though they praise them more than anything. If you're not familiar of the issue above, do you have any impressions, comments both pros/cons on these drives.

I ask because I considered intels latest, not the SLC extreme but the MLC, cheaper version for my OS drive. I currently have a raptor sure but lets pretend money wasn't an issue (and Intels extreme wasn't available).

Have you looked at the G.Skill Titans? They are not a bad price at all and so far the initial reviews are looking very good.

If money was no issue I would pick at least 4 SSD drives on Raid0 with a good controller like an Adaptec 3405.

[drgnfang]

If you're going RAID0 do you need a hardware controller? I ask because in a different thread it was pointed out that a HW controller would be overkill for my planned build unless I was going with SAS drives.

To the original point... Corsair should have some new drives out, MLC with Samsung chips and controller.

http://www.hardfolding.com/fhtag.php/mem/649494/11/3.png (http://www.hardfolding.com/fh_stats/?pz=102&tnum=33&id=649494)

[alamone]

If your perc5/i has SATA breakout cables, then I'd just get a 3-in-2 backplane for 3.5 drives or a 4-in-1 backplane for 2.5 drives. But you have to make sure the backplane supports dual porting. I.e. on the backside, you see a primary and secondary sata connector for each drive.

In my case, I have 2 savvio 15k.1s, they're stuck into GUP Japan smartdrive proof25 which basically converts them to regular 3.5 disks, and then they go into an icydock 3-in-2 SAS backplane w/ dual port support. (I don't recommend the icydock though - they made the dimensions a little too big and I really had to mash it into my case / bend steel to mount it).

It basically costs the same as buying those adaptors, and you get the benefit of hotswap too. But you need some free 5.25 bays to do it.

[thebeephaha]

So one of these (http://www.newegg.com/Product/Product.aspx?Item=N82E16816119006) (which I own)

http://c1.neweggimages.com/NeweggImage/productimage/16-119-006-02.jpg

http://c1.neweggimages.com/NeweggImage/productimage/16-119-006-04.jpg

It has dual ports. So just use this with my two Savvios and just for each drive use both connectors?

Also I just updated my Perc 5 with the latest LSI firmware and drivers so in theory it should work?

BTW thanks everyone for all this useful information!

[alamone]

Yep, that should do it.

One thing though, your card might be finicky about the order of ports, so if they don't get detected, try swapping the cable order around. On my adaptec, all 4 connections on my 2 savvios didn't get detected until I put them in a certain order, for some reason. Maybe it expects the primary or secondary link on an earlier port or something, I don't know.

On my adaptec, you can tell if dual porting is working because when you click on the drive, it says PHY0 3.0 GB/s and PHY1 3.0GB/s, indicating two physical connections to the drive. I'm not sure how it works on the megaraid software, but let me know how it goes.

[Ockie]

So one of these (http://www.newegg.com/Product/Product.aspx?Item=N82E16816119006) (which I own)

http://c1.neweggimages.com/NeweggImage/productimage/16-119-006-02.jpg

http://c1.neweggimages.com/NeweggImage/productimage/16-119-006-04.jpg

It has dual ports. So just use this with my two Savvios and just for each drive use both connectors?

Also I just updated my Perc 5 with the latest LSI firmware and drivers so in theory it should work?

BTW thanks everyone for all this useful information!


Get the supermicro version, much better and has a SFF cable instead, much cleaner :)

[alamone]

AFAIK the supermicro 1-in-4 only supports single port, since it has only 1 SFF connector on it for 4 ports total. The 2-in-8 supports dual port since it has dual expanders on it, but it doesn't have the tab indentations in the middle so it probably won't fit in most people's cases with the metal tabs.

[thebeephaha]

You guys are awesome.

[Ockie]

AFAIK the supermicro 1-in-4 only supports single port, since it has only 1 SFF connector on it for 4 ports total. The 2-in-8 supports dual port since it has dual expanders on it, but it doesn't have the tab indentations in the middle so it probably won't fit in most people's cases with the metal tabs.

Technically it's not dual expanders. It also doesn't need the indentations because it's only a regular 5.25" height (same size as regular CDRom drive).