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Hello my friends,
For a very long time now, I have wanted something faster than IDE RAID-0.
I have been keeping an eye on the LSI MegaRaid 320-2E since even before it was released. The card needs no introduction I am sure.
After long time of research and saving, I have decided to get the LSI Megaraid 320-2E / Dell Perc4e-DC and SCSI drives to take advantage of it's BW.
I would kindly like to ask some questions. I would like to point out that I have searched this forum and many others, but I have not come across any convincing answers - if any at all.
Before we begin, can I ask what the maximum BW this card can REALLY handle is? I understand that it is a bridged PCI-X at 100MHz, but what is the maximum transfer speed that this card will be able to handle?
Now shall we begin?
Firstly, is there any significant difference between the two cards? Has Dell Crippled anything int the 320-2E card while rebranding it? (I have just bought a Perc4e simply because the LSI is extremely rare in the UK)
Secondly, the SCSI drives.
I have seen from benchmarks that 4-5 drives in Raid0 give the best performance as long as you have the BW, which at last this card provides. I am planning on getting 6x18GB drives @ 15K RPM and Ultra320 interface to put in Raid-0, 3 drives on U320 each channel. Will the card (working at PCI-X 100MHz Bridged internally apparently), be able to provide enough BW for all 6 drives at 15K+U320?
Now, Either I see 10K U320 or 15K U160, both around the same price. It is very rare to see an 18GB (cheapest option for me) at 15Krpm AND U320. My question is, since each drive reads at around 70MB/s Max, and U160 provides 2x that, am I going to really need the U320 interface for much apart from buffered reads?
These buffered reads seem to actually communicate at full speed, but may I ask, how often, or how many percent of time doing average tasks will it really be doing buffered reads at full speed as opposed to normal reads at 70MB/s. Realistically, will there be any Significant gains (in windows boot-up time, loading of apps, file copying, defragging, autocad, gaming etc) with U320 as opposed to U160? What percentage difference can I expect roughly on average?
Am I right in thinking that if I only had 2 drives per channel, then if each drive were to read at 70MB/s simultaneously, the interface would be fast enough at U160 to continualy take data from both SCSI drives as they worked at max speed in real time, as the interface is over 2x faster on each drive? Rough example: if each drive were reading at 70MB/s, 140MB/s needs to be transferred on the bus every second, and the U160 will be enough at reading at 160MB/s? And now if I add another drive on each channel, the interface is not fast enough to keep up with the data read because I would now need to read data at 210MB/s, ie I would be best having U360 interface here?
Appologies if this is not clear. It is the best that I can explain myself.
Next question:
With 6 drives, and this ultra fast hardware RAID solution, Should I choose a much smaller stripe size compared with recomended for IDE RAID? (64K) - so that even the smaller than 64k files will be split up onto all 6 drives for higher access. Ofcourse the trade-off is fragmentation. What would be the recomended stripe size? And ofcourse, what whould be the corrosponding recomended cluster size?
The problem here is that I don't use large files very much (I don't do much video editing etc). Normal Programs load very small files, and I want access to these files quickly through all 6 drives. I think that most files programs load are around or smaller than 64k, which would mean that only one drive would be being used, my parallel raid array would be useless here. Maybe a stripe size of 16k or even 8k would be better?
Finally, are there any general recomendations and suggestions?
I would greatly appreciate any kind of help and input on this matter.
Sorry if my explanations arn't too clear... It is the best that I can do.
Thank you and Kind Regards,
-- Shahzad Ali
Cambridge
UK
For a very long time now, I have wanted something faster than IDE RAID-0.
I have been keeping an eye on the LSI MegaRaid 320-2E since even before it was released. The card needs no introduction I am sure.
After long time of research and saving, I have decided to get the LSI Megaraid 320-2E / Dell Perc4e-DC and SCSI drives to take advantage of it's BW.
I would kindly like to ask some questions. I would like to point out that I have searched this forum and many others, but I have not come across any convincing answers - if any at all.
Before we begin, can I ask what the maximum BW this card can REALLY handle is? I understand that it is a bridged PCI-X at 100MHz, but what is the maximum transfer speed that this card will be able to handle?
Now shall we begin?
Firstly, is there any significant difference between the two cards? Has Dell Crippled anything int the 320-2E card while rebranding it? (I have just bought a Perc4e simply because the LSI is extremely rare in the UK)
Secondly, the SCSI drives.
I have seen from benchmarks that 4-5 drives in Raid0 give the best performance as long as you have the BW, which at last this card provides. I am planning on getting 6x18GB drives @ 15K RPM and Ultra320 interface to put in Raid-0, 3 drives on U320 each channel. Will the card (working at PCI-X 100MHz Bridged internally apparently), be able to provide enough BW for all 6 drives at 15K+U320?
Now, Either I see 10K U320 or 15K U160, both around the same price. It is very rare to see an 18GB (cheapest option for me) at 15Krpm AND U320. My question is, since each drive reads at around 70MB/s Max, and U160 provides 2x that, am I going to really need the U320 interface for much apart from buffered reads?
These buffered reads seem to actually communicate at full speed, but may I ask, how often, or how many percent of time doing average tasks will it really be doing buffered reads at full speed as opposed to normal reads at 70MB/s. Realistically, will there be any Significant gains (in windows boot-up time, loading of apps, file copying, defragging, autocad, gaming etc) with U320 as opposed to U160? What percentage difference can I expect roughly on average?
Am I right in thinking that if I only had 2 drives per channel, then if each drive were to read at 70MB/s simultaneously, the interface would be fast enough at U160 to continualy take data from both SCSI drives as they worked at max speed in real time, as the interface is over 2x faster on each drive? Rough example: if each drive were reading at 70MB/s, 140MB/s needs to be transferred on the bus every second, and the U160 will be enough at reading at 160MB/s? And now if I add another drive on each channel, the interface is not fast enough to keep up with the data read because I would now need to read data at 210MB/s, ie I would be best having U360 interface here?
Appologies if this is not clear. It is the best that I can explain myself.
Next question:
With 6 drives, and this ultra fast hardware RAID solution, Should I choose a much smaller stripe size compared with recomended for IDE RAID? (64K) - so that even the smaller than 64k files will be split up onto all 6 drives for higher access. Ofcourse the trade-off is fragmentation. What would be the recomended stripe size? And ofcourse, what whould be the corrosponding recomended cluster size?
The problem here is that I don't use large files very much (I don't do much video editing etc). Normal Programs load very small files, and I want access to these files quickly through all 6 drives. I think that most files programs load are around or smaller than 64k, which would mean that only one drive would be being used, my parallel raid array would be useless here. Maybe a stripe size of 16k or even 8k would be better?
Finally, are there any general recomendations and suggestions?
I would greatly appreciate any kind of help and input on this matter.
Sorry if my explanations arn't too clear... It is the best that I can do.
Thank you and Kind Regards,
-- Shahzad Ali
Cambridge
UK