Upgrading E450 SCSI
We currently have a Sun Enterprise 450 that we would like to use as a fileserver. However, the condition is that we need to be able to get something faster than the Sun-shipped UltraSCSI-1 (40 MB/s) interfaces. We don't care about the bottom 4 drive slots (on-board controller). I'm fairly certain the LSI2x320(R) series would be compatible, but searching on Google found a link (which I've lost) that said the backplanes are SE terminated, meaning that even if we installed a U320 LVD SCSI card, the drives would still run at 40MB/s because that is the limitation of SE (as opposed to LVD). However, since this is the only place that I've seen mention that the backplanes themselves are terminated, I'm wondering if all that needs to be done is to replace the internal Sun-shipped SE SCSI cables with LVD cables that have termination at the end of the cable.
Help is greatly appreciated! The alternative to using our E450 would be to buy overpriced HP hard drives (since rails from HP are not available separately, and the only other SCSI machines we have are HP), which I would really prefer we didn't do. Also, I'm not aware of any Sun systems that have as many drive bays as the E450 does, unless we were to buy an external array.
[1254 byte] By [
ywlke287] at [2007-11-26 11:53:31]
# 1
Hello,
I don't think that the optional 8-slot backplane (circuit board itself ) supports LVD SCSI (or higher speed than 40MHz on 16-Bit bus) despite from the integrated SE SCSI terminator. LVD cables use twisted-pairs to limit crosstalk, but the usual cables Ultra SCSI (upto 40 MHz) cables are straight parallel.
The figure (of the 8-Slot SCSI Backplane) in the Sun System Handbook isn't clear, there is only a single 68p SCSI connector (J0402) shown, but the backplane is split into two SCSI buses. Maybe the second connector is located behind D0703 (but not labeled on the drawing).
I'm wondering if all that needs to be done is to replace the internal Sun-shipped SE SCSI cables with LVD cables that have termination at the end of the cable.
The terminator has to be located behind the last device. This 'last device' is on the backplane (one of the drives).
The alternative to using our E450 would be to buy overpriced HP hard drives (since rails from HP are not available separately, and the only other SCSI machines we have are HP), which I would really prefer we didn't do.
Get an external enclosure or array. Using faster internal drives in the E450 involves a lot of modifications and voids any service contract.
Michael
Reviewed 'The Book of SCSI' by Gary Field, Peter M. Ridge et al
Added notes regarding backplane
Message was edited by:
MAALATFT
# 2
Here is a diagram of the 8-slot backplane,
from a non-Sun 3rd party web site.That site has an old copy of the SSH.
http://www.sunshack.org/data/sh/2.1/infoserver.central/data/syshbk/Devices/SCSI /SCSI_U450_8Slot_Bkpl.html
Michael is correct on the two 68-pin connectors, J0402 and D0703,
one each for the data cables of four of the disk positions.
The backplane is indeed its own terminator.
( By the wa, document URL links are broken on that web site. If you need any
referenced documents, search for them manually at Docs.Sun.Com )
Adiitionally, from that same 3rd party web site,
is the E450 wiring diagram, showing most of the important connection paths:
http://www.sunshack.org/data/sh/2.1/infoserver.central/data/syshbk/Devices/Wiri ng_Dgms/WIR_E450.html
# 3
We do not have any contracts with Sun. Would it be at all possible to modify the backplane in such a way that it could run in LVD mode (i.e. to ignore the onboard terminator and use the terminator attached to the cable)? I have worked with other backplane systems that do not have the terminator on the backplane itself. An interesting thing I have found is that Sun did, at one point, sell HVD (Sym22802/53c876), LVD (QLogic QLA10162), and U320 (LSI22320-R,RS,S) SCSI cards for the E450, but perhaps this was only for attachment of external devices?
Also, I would think the backplane itself should be able to support LVD since 1: the distance between connectors is so short and 2: I've only heard that <i>cables</i> need to be in twisted pairs; I think the circuitry probably is less of an issue, but I'm not sure.
Another point I've found interesting is that the E450 has always shipped with Ultra160 drives, its just that Sun "does not recognize the Ultra160 capability of these disks" (or something similar to that).
As for external arrays, do you have any suggestions as to what models would work well and where I could find reasonably/inexpensively priced ones (eBay is not an option)?
# 4
Hello,
Would it be at all possible to modify the backplane in such a way that it could run in LVD mode (i.e. to ignore the onboard terminator and use the terminator attached to the cable)?
The terminator circuits are integrated (surface mounted) on the backplane. The (LVD) controller checks the voltage of DIFF-SENSE (pin 11). If the voltage is below 0.6 Volt (GND on single-ended devices) it switches to SE mode because single-ended devices are present. This information is from 'The Book of SCSI'. I assume that the backplane ties pin 11 to GND.
Sun did, at one point, sell HVD (Sym22802/53c876), LVD (QLogic QLA10162), and U320 (LSI22320-R,RS,S) SCSI cards for the E450, but perhaps this was only for attachment of external devices?
Yes ! The HVD e.g. for the StorEdge D1000/A1000/L9, the LVD or U320 for more recent arrays and tape systems.
As for external arrays, do you have any suggestions as to what models would work well and where I could find reasonably/inexpensively priced ones (eBay is not an option)?
You can review the following thread and my comment !
http://forum.sun.com/jive/thread.jspa?threadID=67148&start=20&tstart=0
Maybe you can buy a refurbished system from Sun or an authorized Sun reseller.
Michael
# 5
Thanks for the quick reply. We may just go with buying HP hard drives, but I will look into your suggestions (like you said, those empty enclosures are pricey, and would make it so that just buying from HP would be cheap). This may be a bit off-topic for this forum, but how do backplanes without built-in termination work if the terminator needs to be next to the last device?
# 6
You asked,
"how do backplanes without built-in termination work if the terminator needs to be next to the last device".
I would imagine that such items from whatever other company,
would be a "dumb" design, with no inherent functional circuitry
other than simple data pathing,
and would have some sort of pass-through connector.
You either pass through to additional cabling to some daisy-chained device,
or you plug in a terminator to such a connector.
... but that's just a guess.That's how JBOD arrays get connected.
# 7
I'd question the E450's ability to serve NFS faster than the SE backplane, even over a GigE interface or two, especially if you have a pair of backplanes installed. Last I checked, which was a long time ago in Solaris 2.7 days, NFS over a GigE on one of these old Sun boxes was only about three or four times as fast as 100Mbit. Still, I have an E450 stuffed with disks, but it's only a resting place for the old 18 and 36G drives we decommission from our retired servers. Before you spend a lot of money on new disks or enclosures, you might do some benchmarks. You can buy the backplanes for $50 or so on Ebay, if you only have one installled.
I did some costing on "upgrading" our E450 with new SCSI disks, and it was cheaper to buy a modern SATA-based array if all we needed was capacity at low cost. Still, the E450's an OK platform, if you can dumpster-dive the parts, have space, and don't mind the electric bill.
# 8
I've already run some tests with the equipment we have installed (we also already have the equipment to "max out" the E450, it's just not installed yet). NFS over the gigabit interface runs about as fast as the SCSI bus will allow it to (40 MB/s*8 bit/byte=320 Mbps). Theoretically we could saturate the gigabit connection if we spread out the drives over more controllers (up to 5). ZFS compression actually allows operations to run a bit faster. Our E450 is kind of used as a repository for any disks that aren't being used elsewhere. I'd think it would be okay if we bought an enclosure and SCSI HBA that was U320 capable, since the PCI 64/66 interface is fast enough to saturate gigabit.
These days just about anything cost less than SCSI (except maybe newer types like SAS), but we're just trying to utilize the equipment we have. For us, budget isn't a huge issue, especially in terms of the electric bill. My main reason for trying to stick on the E450 is that it has 20 disk bays (I have not seen this in any other server, unless it had an external array) and can run Solaris (therefore ZFS). It'd be nice if Sun still made a server that had that many SCSI disk bays (the x4500 is nice, but I think it would actually hit the invisible ceiling that is our budget).
