SCSI newb suffering slow transfer speeds

[Triophile]

Afternoon from sunny (not) London, England, everyone.

I've been a happy PC user for a good few years now, but have recently decided to branch out slightly and start learning a little about server hardware, particularly SCSI drives and HBAs/RAID cards.

I've had a couple of large, noisy servers come and go now, but have hung onto some of the cards and drives, as even the old stuff seems to produce reasonable speeds. I am, however, having problems with sluggish transfers on the current lash-up: an Intel RAID Controller SRCU42L IIRRZ1CHLS 64-bit PCI-X Ultra320 SCSI Low Profile card, and a 300GB Fujitsu MAW3300NC U320 hard drive.


The card is PCI-X, but appears to be compatible with the 32-bit PCI slots on my non-server motherboard, a Gigabyte GA-EP43-S3L (a standard, consumer Socket-775 board); the card self-tests OK, and finds the single drive fine. Both the card and disk are shown as working properly under Windows (Vista Business 32-bit).

The hard drive has an SCA80 socket, and I've got it connected to the card through an adapter (SCA80 to 68-pin, with separate Molex for power, and jumpers for IDs, spindle delay, etc).

When I run HD Tune to check the drive tranfer speeds, I'm getting reads and writes of around 40-50MB/s. This seems very slow. As I'm a newb, I assume I'm missing something obvious.

AFAIA, a single 32-bit PCI slot can transfer about 150MB/s, and despite the fact that the 64-bit Intel card is running in a 32-bit slot, 50MB/s isn't even close to saturating the 32-bit PCI bus on my motherboard. Is the SCA80 to 68-pin adapter causing problems? I've used the same card and cable, also in a 32-bit PCI slot on a different consumer mobo with some 73GB 68-pin SCSI drives, and got the 80-90MB/s I was expecting for those particular drives (operating as single drives).

The IBM drive was one of two previously in a RAID 0 array in an IBM server. I converted it to a basic disk from a dynamic disk using EaseUS, and formatted it to NTFS.

Any advice will be greatly appreciated.

Regards, Jon.

 

[imagoon]

Is it terminated properly? The adapter may be the problem.

SCA80 / ultra320 is a dead tech by the way. You will rarely see it in the wild any more. Everything is SAS.

 

[dave_the_nerd]

I KNOW you read the RAID card's manual to make absolutely sure it wouldn't burn out if inserted into a PCI slot... right?

Anyway, if it were terminated improperly, you'd probably be getting other goofy things happening. A format w/ verification would have failed, for sure.

If the drive's the only thing on the bus, it should have it's termination jumper set.

68-80 pin adapters never worked super well for me. Could be a noisy cable.

40-50 MB/sec is kind of at the low end of the spectrum of what that drive is capable of. (~75 being more typical.) It's not great, but it's not so bad that I wouldn't consider other possible causes. (Which drive you're booting from, type of workload, etc.) The 320MB/Sec number is obviously the maximum bandwidth available for all the devices on the SCSI chain.

I'm also not sure how "smart" the controller card is. It's probably suffering from being in a PCI slot and not a PCI-X. Just because your PCI bus has 133 MB/sec of bandwidth available doesn't mean a 64-bit 66MHz RAID controller working at 32-bit/33MHz is going to be able to utilize all of it.

I'd also point out that PCI is a shared bus - how many other PCI cards do you have installed?

 

[greenhawk]

I can only repeat what the others have touched on.

PCI is 133MB/s shared between all PCI deivces. Added to the detail that a lot of current boards for the last few years have been using bridge chips to provide a PCI slot, adding overheats and slowing speeds.

As to the drive speed, nearly sounds like you do not have the correct termintation / cables needed to run the drive. Without correct scsi termination the controller will drop to about 40MB/s max IIRC. Though I did have a dual channel SCSI 160 controller I managed to damage it somehow and the onboard terminator broke on one channel so it would never go faster than 40MB/s.

as to the u320 spec, you need to load the channel up (with multiple drives) to get that speed, assuming your host controller can make use of that much speed.

 

[Triophile]

Thanks for the replies guys.

I realise that 320MB/s is the full bandwidth that the bus is capable of, and not what anything connected to it will necessarily deliver

The SCSI cable has a terminator built into the last connector in the chain, and that's what the drive is connected to. That said, I've just realised that the SCSI ID on the converter is set to 4. Should a device occupying the final connector on a cable be set by default to an ID value like 15?

RTFM? Perish the thought! I tried the card in an expendable machine first, and then slipped it into the mobo it's in now. No magic silicon smoke yet

The only other PCI card in the mobo is a TV card. I could certainly yank that and see if I get any improvement. I've also got another cable somewhere; I'll dig that out and try it.

I realise U320 is a crusty technology, but I got two 300GB 10k drives in a server which I sold for more than I paid for it. According to the specs, the max transfer speed off the disc is about 130MB/s (presumably only around the outer periphery of the hard discs themselves), so if I can RAID 0 both of them and upgrade to a PCI-e U320 SCSI RAID card, that's a decent chunk of usably fast storage for not much cash.

I've got a PERC5i SAS RAID card with battery and a 500GB SAS drive I managed to get off eBay nice and cheap (it was listed in the wrong category). Yes, that's pretty fast, but SAS stuff is generally beyond the budget for IT gear which my girlfriend allows me

If it turns out that the card is simply not happy where it is now, it's not the end of the world - it only cost me a fiver. That said, be nice to get some better speed out of it, so I'll try the different cable, and removing the TV card.

Cheers, Jon.

 

[dave_the_nerd]

Thanks for the replies guys.

The SCSI cable has a terminator built into the last connector in the chain, and that's what the drive is connected to. That said, I've just realised that the SCSI ID on the converter is set to 4. Should a device occupying the final connector on a cable be set by default to an ID value like 15?

ID is irrelevant. passthrough in-cable terminators are the devil. The drive itself should have a terminator built in. (Pull jumper to disable.) Use one, and only one terminator. (Notwithstanding the built in host-end termination on the card.)

The only other PCI card in the mobo is a TV card. I could certainly yank that and see if I get any improvement. I've also got another cable somewhere; I'll dig that out and try it.

Pull it and try it. Can't hurt nuthin'.

 

[tweakboy]

It's transferring @ 4x . If it was on the motherboard it would be MUCH MUCH faster.

Its the card and the limitation.

 

[imagoon]

It's transferring @ 4x . If it was on the motherboard it would be MUCH MUCH faster.

Its the card and the limitation.

What? 4x makes no sense in PCI.

33Mhz 32bit PCI = shared 133MB/s
33Mhz 64bit PCI = shared 266MB/s

Unless he has a ton of PCI cards, 33Mhz PCI 32bit can handle a single drive.

 

[greenhawk]

It's transferring @ 4x . If it was on the motherboard it would be MUCH MUCH faster.

want to expand on that?

as to the "on the motherboard", you did read the thread and see it is scsi u320 right? the older pre-sata/sas format used in servers? I have not seen a motherboard with onboard scsi for several years now, espically outside the dual cpu xeon motherboard range.

 

[Triophile]

OK, tried it without the TV card, and no difference. Same with a different cable, so I swapped the Intel RAID card out for an old Adaptec 39160 U160 dual-channel RAID card, and now things are happier. Sorry, should have taken my testing a bit further before posting...

Now, with the 39160, the drive with adapter shows at around 75MB/s in HD tune, and around 85MB/s in PC Wizard 2012. I tried a 15K U320 SCSI with 68-pin socket (ie, no adapter), and that showed roughly the same speeds.

Thanks for the pointers guys.

I'm gradually saving up for a new mobo and processor, and think I'll try and scrape together the readies for a mobo with two PCI-e x16 slots, so I can get the GFX in one, and a RAID card of some description in the other (assuming it runs at a minimum of x8).

Cheers, Jon.

 

[imagoon]

Most of the controllers are either pci-e 4x or 8x. Thing is that the PCI-e 2.1 spec or PCI-e 3.0 specs are in excess of 500MB/s for one channel. For home users a 4x card is often overkill. I wouldn't be to worried about 8x etc.