=) i know, but since we have many proprietary firmware, a opensource firmware (like openbios) could be very nice :D hehehehe i will use linux raid (i´m sure it´s very good) it´s really fast, and work with hotswap too (ok there´s some userspace programs to allow it to work ok even with wrong kernel hotswap problems, but when kernel can release and replug it without problems we don´t need userspace programs... userspace check each new hotpluged volume, if uuid is = some raid uuid device, it put the device in the right raid device (i made it with a php script =) hehehe) ) 2011/1/20 Keld Jørn Simonsen <keld@xxxxxxxxxx>: > On Wed, Jan 19, 2011 at 09:18:22PM -0200, Roberto Spadim wrote: >> a good idea.... >> why not start a opensource raid controller? >> what we need? a cpu, memory, power supply with battery or capacitor, >> sas/sata (disk interfaces), pci-express or another (computer >> interface) > > Why? because of some differences in memory speed? > > Normally software raid is faster than hardware raid, as wittnessed by > many here on the list. The mentioning of max 350 MB/s on a SW raid > is not true, 350 MB/S is what I get out of a simple box with 4 slightly > oldish SATA drives. 16 new fast SATA drives in SW raid6 should easily go beyond > 1000 MB/s, given that there are not other bottlenecks in the system. > > Linux SW raid goes fairly close to theoretical maxima, given adequate > HW. > > > best regards > keld > >> it don?t need a operational system, since it will only run one program >> with some threads (ok a small operational system to implement threads >> easly) >> >> we could use arm, fpga, intel core2duo, atlhon, xeon, or another system... >> instead using a computer with ethernet interface (nbd nfs samba or >> another file/device sharing iscsi ethernet sata), we need a computer >> with pci-express interface and native operational system module >> >> >> 2011/1/19 Roberto Spadim <roberto@xxxxxxxxxxxxx>: >> > the problem.... >> > if you use iostat, or iotop >> > with software raid: >> > you just see disk i/o >> > you don?t see memory (cache) i/o >> > when using hardware raid: >> > you just see raid i/o (it can be a cache read or a real disk read) >> > >> > >> > if you check memory+disk i/o, you will get similar values, if not, you >> > will see high cpu usage >> > for example you are using raidx with 10disks on a hardware raid >> > change hardware raid to use only disks (10 disks for linux) >> > make the same raidx with 10disks >> > you will get a slower i/o since it have a controler between disk and cpu >> > try it without hardware raid cpu, just a (sas/sata) optimized >> > controller, or 10 (sata/sas) one port >> > you still with a slow i/o then hardware controller (that?s right!) >> > >> > now let?s remove the sata/sas channel, let?s use a pci-express >> > revodrive or pci-express texas ssd drive >> > you will get better values then a hardware raid, but... why? you >> > changed the hardware (ok, i know) but you make cpu more close to disk >> > if you use disks with cache, you will get more speed (a memory ssd >> > harddisk is faster than a harddisk only disk) >> > >> > why hardware are more faster than linux? i don?t think they are... >> > they can make smaller latencies with good memory cache >> > but if you computer use ddr3 and your hardware raid controller use i2c >> > memory, your ddr3 cache is faster... >> > >> > how to benchmark? check disk i/o+memory cache i/o >> > if linux is faster ok, you use more cpu and memory of your computer >> > if linux is slower ok, you use less cpu and memory, but will have it >> > on hardware raid... >> > if you upgrade you memory and cpu, it can be faster than you hardware >> > raid controller, what?s better for you? >> > >> > want a better read/write solution for software raid? make a new >> > read/write code, you can do it, linux is easier than hardware raid to >> > code! >> > want a better read/write solution for hardware raid? call your >> > hardware seller and talk, please i need a better firmware, could you >> > send me? >> > >> > got? >> > >> > >> > 2011/1/19 Stefan /*St0fF*/ Hübner <stefan.huebner@xxxxxxxxxxxxxxxxxx>: >> >> @Roberto: I guess you're right. BUT: i have not seen 900MB/s coming from >> >> (i.e. read access) a software raid, but I've seen it from a 9750 on a >> >> LSI SASx28 backplane, running RAID6 over 16disks (HDS722020ALA330). So >> >> one might not be wrong assuming on current raid-controllers >> >> hardware/software matching and timing is way more optimized than what >> >> mdraid might get at all. >> >> >> >> The 9650 and 9690 are considerably slower, but I've seen 550MB/s thruput >> >> from those, also (I don't recall the setup anymore, tho). >> >> >> >> Max reading I saw from a software raid was around 350MB/s - so hence my >> >> answers. And if people had problems with controllers which are 5 years >> >> or older by now, the numbers are not really comparable... >> >> >> >> Now again there's the point where there are also parameters on the >> >> controller that can be tweaked, and a simple way to recreate the testing >> >> scenario. We may discuss and throw in further numbers and experience, >> >> but not being able to recreate your specific scenario makes us talk past >> >> each other... >> >> >> >> stefan >> >> >> >> Am 19.01.2011 20:50, schrieb Roberto Spadim: >> >>> So can anybody help answering these questions: >> >>> >> >>> - are there any special options when creating the RAID0 to make it >> >>> perform faster for such a use case? >> >>> - are there other tunables, any special MD / LVM / file system / read >> >>> ahead / buffer cache / ... parameters to look for? >> >>> >> >>> lets see: >> >>> what?s your disk (ssd or sas or sata) best block size to write/read? >> >>> write this at ->(A) >> >>> what?s your work load? 50% write 50% read ? >> >>> >> >>> raid0 block size should be multiple of (A) >> >>> *****filesystem size should be multiple of (A) of all disks >> >>> *****read ahead should be a multiple of (A) >> >>> for example >> >>> /dev/sda 1kb >> >>> /dev/sdb 4kb >> >>> >> >>> you should use 6kb... you should use 4kb, 8kb, 16kb (multiple of 1kb and 4kb) >> >>> >> >>> check i/o sheduller per disk too (ssd should use noop, disks should >> >>> use cfq, deadline or another...) >> >>> async and sync option at mount /etc/fstab, noatime reduce a lot of i/o >> >>> too, you should optimize your application too >> >>> hdparm each disk to use dma and fastest i/o options >> >>> >> >>> are you using only filesystem? are you using somethink more? samba? >> >>> mysql? apache? lvm? >> >>> each of this programs have some tunning, check their benchmarks >> >>> >> >>> >> >>> getting back.... >> >>> what?s a raid controller? >> >>> cpu + memory + disk controller + disks >> >>> but... it only run raid software (it can run linux....) >> >>> >> >>> if you computer is slower than raid cpu+memory+disk controller, you >> >>> will have a slower software raid, than hardware raid >> >>> it?s like load balance on cpu/memory utilization of disk i/o (use >> >>> dedicated hardware, or use your hardware?) >> >>> got it? >> >>> using a super fast xeon with ddr3 and optical fiber running software >> >>> raid, is faster than a hardware raid using a arm (or fpga) ddrX memory >> >>> and sas(fiber optical) connection to disks >> >>> >> >>> two solutions for the same problem >> >>> what?s fast? benchmark it >> >>> i think that if your xeon run a database and a very workloaded apache, >> >>> a dedicated hardware raid can run faster, but a light xeon can run >> >>> faster than a dedicated hardware raid >> >>> >> >>> >> >>> >> >>> 2011/1/19 Wolfgang Denk <wd@xxxxxxx>: >> >>>> Dear =?ISO-8859-15?Q?Stefan_/*St0fF*/_H=FCbner?=, >> >>>> >> >>>> In message <4D361F26.3060507@xxxxxxxxxxxxxxxxxx> you wrote: >> >>>>> >> >>>>> [in German:] Schätzelein, Dein Problem sind die Platten, nicht der >> >>>>> Controller. >> >>>>> >> >>>>> [in English:] Dude, the disks are your bottleneck. >> >>>> ... >> >>>> >> >>>> Maybe we can stop speculations about what might be the cause of the >> >>>> problems in some setup I do NOT intend to use, and rather discuss the >> >>>> questions I asked. >> >>>> >> >>>>>> I will have 4 x 1 TB disks for this setup. >> >>>>>> >> >>>>>> The plan is to build a RAID0 from the 4 devices, create a physical >> >>>>>> volume and a volume group on the resulting /dev/md?, then create 2 or >> >>>>>> 3 logical volumes that will be used as XFS file systems. >> >>>> >> >>>> Clarrification: I'll run /dev/md* on the raw disks, without any >> >>>> partitions on them. >> >>>> >> >>>>>> My goal is to optimize for maximum number of I/O operations per >> >>>>>> second. ... >> >>>>>> >> >>>>>> Is this a reasonable approach for such a task? >> >>>>>> >> >>>>>> Should I do anything different to acchive maximum performance? >> >>>>>> >> >>>>>> What are the tunables in this setup? [It seems the usual recipies are >> >>>>>> more oriented in maximizing the data troughput for large, mostly >> >>>>>> sequential accesses - I figure that things like increasing read-ahead >> >>>>>> etc. will not help me much here?] >> >>>> >> >>>> So can anybody help answering these questions: >> >>>> >> >>>> - are there any special options when creating the RAID0 to make it >> >>>> perform faster for such a use case? >> >>>> - are there other tunables, any special MD / LVM / file system / >> >>>> read ahead / buffer cache / ... parameters to look for? >> >>>> >> >>>> Thanks. >> >>>> >> >>>> Wolfgang Denk >> >>>> >> >>>> -- >> >>>> DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel >> >>>> HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany >> >>>> Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@xxxxxxx >> >>>> Boykottiert Microsoft - Kauft Eure Fenster bei OBI! >> >>>> -- >> >>>> To unsubscribe from this list: send the line "unsubscribe linux-raid" in >> >>>> the body of a message to majordomo@xxxxxxxxxxxxxxx >> >>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >> >>>> >> >>> >> >>> >> >>> >> >> >> >> -- >> >> To unsubscribe from this list: send the line "unsubscribe linux-raid" in >> >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> >> >> > >> > >> > >> > -- >> > Roberto Spadim >> > Spadim Technology / SPAEmpresarial >> > >> >> >> >> -- >> Roberto Spadim >> Spadim Technology / SPAEmpresarial >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-raid" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- Roberto Spadim Spadim Technology / SPAEmpresarial -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
