> ________________________________ > From: Matthew Wilcox [mailto:matthew@xxxxxx] > Sent: Thu 12/11/2008 5:44 AM > To: Raz Ben-Yehuda > Cc: linux-ide@xxxxxxxxxxxxxxx; linux-scsi@xxxxxxxxxxxxxxx > Subject: Re: Intel X25-M MLC SSD benchmarks > > On Thu, Dec 11, 2008 at 12:12:37AM +0200, Raz Ben-Yehuda wrote: >> I did not want to dive into details because it does not matter. Whether >> noop,deadline, deadline parameters... >> As for the controller I used 4 different controllers. Adaptec,AHCI and >> Intel as Integrated chips on the 1025W-UR supermicro motherboard, and a >> 4-th controller SuperMicro UIO Adaptec aac card. >> All gave same results for most dd writes commands. >> dd if=/dev/zero of=/dev/sda bs=1M count=1000 oflag=direct , and many >> other variants such erase block size ( 128K ) , several erase block size >> and so on. Kernel is 2.6.18-8.el5. > >>>OK, I suspect you aren't giving the drive enough work to do for it to >>>perform at its best. Try doing something like this: > >>>for i in $(seq 0 9); do \ > >> dd if=/dev/zero of=/dev/sda bs=1M count=1000 oflag=direct \ > >> seek=$(($i * 1000)) & \ >>>done > did that. nothing. also, I would like to note that IO flow is quite weird.iostats reports 70GB/s in the first few seconds, and then it degrades to 20 MB/s and less. could it be that I am not erase-block aligment ? how does SSD aligments interacts with a controller ? iostats looks like that:Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrt sda 746.46 0.00 191143.43 0 189232 sda 546.53 0.00 139912.87 0 141312 sda 480.00 0.00 122880.00 0 122880 sda 469.00 0.00 120016.00 0 120016 sda 347.00 0.00 88880.00 0 88880 sda 403.96 0.00 103413.86 0 104448 sda 349.00 0.00 89296.00 0 89296 sda 424.00 0.00 108544.00 0 108544 sda 480.00 0.00 122880.00 0 122880 sda 184.00 0.00 47104.00 0 47104 sda 467.00 0.00 119600.00 0 119600 sda 408.00 0.00 104448.00 0 104448 sda 320.00 0.00 81920.00 0 81920 sda 357.00 0.00 91344.00 0 91344 sda 195.00 0.00 49968.00 0 49968 sda 280.00 0.00 71680.00 0 71680 sda 475.25 0.00 121663.37 0 122880 sda 85.00 0.00 21712.00 0 21712 sda 235.00 0.00 60208.00 0 60208 sda 216.00 0.00 55296.00 0 55296 sda 112.00 0.00 28672.00 0 28672 sda 245.00 0.00 62672.00 0 62672 sda 72.00 0.00 18432.00 0 18432 sda 75.00 0.00 19248.00 0 19248 sda 141.00 0.00 36048.00 0 36048 sda 11.00 0.00 2864.00 0 2864 sda 200.00 0.00 51200.00 0 51200 sda 88.00 0.00 22528.00 0 22528 sda 160.00 0.00 40960.00 0 40960 sda 118.81 0.00 30415.84 0 30720 sda 32.00 0.00 8192.00 0 8192 sda 128.00 0.00 32768.00 0 32768 sda 77.00 0.00 19664.00 0 19664 any idea ? >> I used all on a supermicro 1025W-UR. Disks have a SAS interface, 80GB. >> Also, I would like to note, I have 8 disks in array, while each one >> perform READS 250 MB/s, together I degrade to 200 MB/s each. As for > >>>That doesn't surprise me; you're probably hitting a limitation either of >>>the array or the cable itself. A SAS cable can run up to 6Gbps, which >>>will be around 600MB/s. So three drives should be able to saturate your >>>SAS cable. If you're using an x4 link, that goes up to 2400MB/s which >>>should be ample for 8 drives ... maybe you're using a 3Gbps cable which >>>would limit each drive to 150MB/s. I am not surprised as well. SSD is quite new for these controller. I am using SAS cable(blue one), and no cx4 can connect to io card controller. anyway, I have contact supermicro for that, I want to bypass the back panel, just to be sure. > -- > Matthew Wilcox Intel Open Source Technology Centre > "Bill, look, we understand that you're interested in selling us this > operating system, but compare it to ours. We can't possibly take such > a retrograde step." > -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
