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#11
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albatros66 wrote:
* Do you think, that internal bus with frequency e.g. 33MHz (or 66MHz) is OK? The newer chips use 133MHz bus (or more ). Note that with enclosure containing 16 SATA drives it becomes feasible to get trasfer rates upt to 300Mbytes/s or more (I know about boxes with RAID5 rates: 200MBytes/s write and 300MBytes/s read) * newer chipsets have the appropriate asic on board which works much faster * newer chipsets suport more cache memory and aslo offer cache memory battery backup ... Well, at least one vendor offers battery backup (which you want) but cannot deliver it. Then, the device I tried gave a satisfactory (for my purpose) performance of about 70 megabytes/sec over SCSI, in RAID 5. Nothing to write home about. The drives could handle this at 33 MB/sec interface rate, but I think the manufacturer claims 133 per drive. Useless, I'd guess. It is the Axus Brownie. Thomas |
#12
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#13
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On Tue, 28 Oct 2003 14:23:18 -0800, Malcolm Weir
wrote: So what? I'd certainly *hope* that the embedded CPU isn't touching the data at all... Actually most of the systems use the CPU for parity calcs * newer chipsets have the appropriate asic on board which works much faster What "appropriate asic"? Works much faster than *what*? The LSI controller (also used by StorageTek's Bladestore ATA offering) uses a dedicated ASIC for this, freeing up the CPU to only do traffic control and config. Scott |
#14
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"albatros66" wrote in message m... * Cost are not much different: varying from 12000 USD to 18000USD for 4TB subsystem ... * familiarity of developers: I'm not developer. I'm "end user" ( not a user at gray end 8-}). I don't need to care about * features - most of the subsystem have almoust the same features - the lists of features are long or very long: ten or more RAID modes, flashilg lamps, SNMP, hot everything etc etc ... Let's take your pick again: which SCSI/FIBRE-to-IDE/SATA array is best from any point of view ??? Is anybody brave enough to answer the question??? I have to answer to my boss because whe are just buying few such devices (some 20TB) ... Can you give any info on what applications you are going to be using the storage for ? It's usually a big factor in choosing the right system. I'm guessing you are looking at something to maybe do archiving if you're looking at IDE based storage ? What do you mean by "familiarity of developers" ? Good to see you're after "flashing lights" as a buying factor ;-) Not enough manufacturers are aware of this ... though Ciprico had a great "Meg-O-Meter" on theirs :-) One company I have a lot of respect for is DigiData (http://www.digidata.com) they're not to huge so they have the time and inclination to talk to you and help sort out any questions/problems you may have and the RAID controllers they've made in the past have always been horribly quick. Regards Mark |
#15
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On Wed, 29 Oct 2003 20:07:47 -0800, Scott wrote:
On Tue, 28 Oct 2003 14:23:18 -0800, Malcolm Weir wrote: So what? I'd certainly *hope* that the embedded CPU isn't touching the data at all... Actually most of the systems use the CPU for parity calcs *delicate shudder* We had a soft-programmable DMA-engine FPGA doing this in 1994, maybe 95. It had a simple "language" which we encoded as the least significant bits of an address to process. The commands we LOAD XOR in data SAVE HALT/INTERRUPT One just pointed the thing at a list of memory addresses and let it get on with it. * newer chipsets have the appropriate asic on board which works much faster What "appropriate asic"? Works much faster than *what*? The LSI controller (also used by StorageTek's Bladestore ATA offering) uses a dedicated ASIC for this, freeing up the CPU to only do traffic control and config. As I'd expect! Although an ASIC is a refinement (over the FPGA). A problem with (oddly enough) more advanced processors doing XOR work is that you have to flush the processor's data cache and pipeline in order to permit the IO processor (the SCSI controller) to access the updated data... (The standard multiprocessor cache coherency problem) Scott Malc. |
#16
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