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8 SATA SSD; 8 vs. 4+4 Raid 10.
Hello,
I have a R710 with H700 integrated raid card and 8*2,5 backplane and right now I’m using a RAID 10 with 4 Intel SSD S3500 and I'm pretty happy with them.
I have bought 4 more of the same SSD and I don't know if it will be better doing a raid 10 with all the 8 SSD or two raid 10 with 4 SSD each one.
By the other hand the H700 is on the integrated pci slot for that, but I think it's only X4 and the H710p is X8; maybe it will have some sense to move it to a X8 pci bay and try to hold the card in some way.
Finally, is it possible to buy another H700 or H710 (the PCI one) and connect from the backplane the SAS A cable to one card and the SAS B cable to the integrated H700; in this way doing 2*Raid 10, each raid 10 will use one card and one PCI bay. Does the R710 work fine (unsuported) with H710 or H730(PCI gen2/gen3...); they seems to have better chip for SSD.
Thanks in advance for your comments.
theflash1932
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December 7th, 2015 08:00
This depends. There is not a way to simply add 4 more drives to an existing RAID 10 - you would have to backup and restore to the new, larger array. If you don't mind doing this, then the resulting performance bump may be worthwhile. If you don't have the time or are not comfortable with this type of operation, then you are better off using two separate arrays.
Leave it in the storage slot ... the H700 will link at x8, plus the storage slot is designed to give priority to the storage subsystem on the bus. Moving it to a different slot "may" still work, but it will likely compete with other bus devices there.
The H710 is not officially supported in the R710. It may work fine, but it is not designed for that system. You "probably" can put in a second controller, but I'm not sure it would be worth the expense, not to mention that it may not work, as it also is not a supported configuration on this server.
festuc
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December 7th, 2015 09:00
Thanks for the reply; I don't mind recreating the raid array at all.
I was asking that because I don't know if the H700 will be limiting the performance of the 8 SSD in raid 10.
I was thinking on the H710 to have better compatibility for SSD.
I will have a teoretical sequential read performance of 4GB/s and think it's the limit of the PCI X8; but maybe the H700 has a slower limit.
pcmeiners
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December 8th, 2015 10:00
The throughput of an SSD array does not appear to follow mechanical disks as drives are added; with mechanical disk adding drives to an array increases performance up to the point of bus saturation, (generally). Many factors are involved. Technology is fairly new, manufacturer do not follow an SSD standard, raid adapters and motherboards buses needed to have faster buses to keep up with fast SSDs, as SSDs can saturate a bus easily; most motherboard and raid adapter technologies are behind SSD technology. As to a second adapter, 1 adapter should be able to come close to or saturate a mobo bus, so a second adapter will not add much.
Basically unless you need a single array for the amount of data of the same data type, as in a single database, you would be better of with 2 raid10 arrays (speed and safety point of view). Hope you have a hotspare, if you have two arrays, you can have a global hotspare
www.kickassnetwork.net
festuc
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December 24th, 2015 02:00
Hello,
I have done test's with 4*SSD Intel S3500 and the max data I got is:
Sequencial read: 1257MB/s
Sequencial write: 1092MB/s
IOPS:
4K-64Thrd Read: 53462
4K-64Thrd Write: 22780
So maybe with that performance a raid 10 won't saturate the bus.
Difucult decisión because of the lack of testing, information, etc....
I'm still deciding which strip size to use (Hyper-V VHDX with Virtual SQL Servers).
Thanks and Merry Christmas.
pcmeiners
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December 24th, 2015 06:00
Went on tweakers.net, looked for benchmarks from larger SSD arrays, could not find any, the benchmarks could be there, I just could not find them, That site runs an amazing amount of raid tests. Look around....
http://tweakers.net/benchdb/suite/13
Testing for the optimal stripe size for a specific program is tedious, only needed to do it it infrequently thankfully. Once, a client's crew and myself spent a solid week bench testing a SQL program for the correct stripe and performance tweaks.
good luck
Merry Christmas