From mboxrd@z Thu Jan 1 00:00:00 1970 From: Leonidas Spyropoulos Subject: Re: Raid0 with btrfs Date: Sat, 7 Aug 2010 15:15:04 +0100 Message-ID: References: <201008051640.51662.hka@qbs.com.pl> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: Hubert Kario , linux-btrfs@vger.kernel.org To: "Sebastian 'gonX' Jensen" Return-path: In-Reply-To: List-ID: On Sat, Aug 7, 2010 at 12:16 PM, Leonidas Spyropoulos wrote: > On Sat, Aug 7, 2010 at 1:03 AM, Sebastian 'gonX' Jensen > wrote: >> On 7 August 2010 00:24, Leonidas Spyropoulos w= rote: >>> On Fri, Aug 6, 2010 at 7:32 PM, Sebastian 'gonX' Jensen >>> wrote: >>>> On 6 August 2010 20:23, Leonidas Spyropoulos = wrote: >>>>> Do I have to change the partition ID flag of each partition? >>>>> Currently is set to fd (Linux Raid autodetect) for used from mdad= m >>>>> mkfs.btrfs supports that or needs to be 83 (Linux) ? >>>> >>>> FD is for mdraid integrated into the Linux kernel. I have mine at = 83. >>>> It won't hurt to have them at FD, but the kernel will spend extra = time >>>> as it probes the devices on boot, causing a slight slowdown. >>> >>> Ok done them id 83 and used 3 devices eventually >>> Using raid0 for data and metadata >>> # mkfs.btrfs -m raid0 -d raid0 /dev/sdc1 /dev/sdd2 /dev/sde2 >>> >>> 2 SATA and 1 ATA drive >>> I thought that ATA will bottleneck the other 2 drives but seems lik= e I gain >>> something from it. >>> Using iozone for benchmark: >>> # iozone -s 8g -r 1024 -i 0 -i 1 >>> with 2 SATA devices and then 3 devices (SATA + ATA): >>> =A0 =A0 =A0 =A0KB =A0reclen =A0 =A0 =A0write =A0 rewrite =A0 =A0 =A0= read =A0 =A0 reread >>> 8388608 =A0 =A01024 =A0134869 =A0139607 =A0 229146 =A0 228800 >>> 8388608 =A0 =A01024 =A0135151 =A0139050 =A0 233461 =A0 235929 >>> >>> The above is with -o compress option enabled and my cpu topped up o= n >>> 100% cpu (both cores) while test and copy huge data. >>> Is it possible I am bottlenecked by my cpu speed? >>> AMD Opteron 165 @ 2700 Mhz >>> >>>>> >>>>> On Thu, Aug 5, 2010 at 3:40 PM, Hubert Kario wro= te: >>>>>> On Thursday 05 August 2010 16:15:22 Leonidas Spyropoulos wrote: >>>>>>> Hi all, >>>>>>> >>>>>>> I want to make a btrfs raid0 on 2 partitions of my pc. >>>>>>> Until now I am using the mdadm tools to make a software raid of= the 2 >>>>>>> partitions /dev/sde2, /dev/sdd2 >>>>>>> and then mkfs.etx4 the newly created /dev/md0 device. >>>>>>> From performance point of view is it better to keep the configu= ration of >>>>>>> mdadm and just format the /dev/md0 device as btrfs OR >>>>>>> delete the raid device and format the 2 partitions /dev/sde2 /d= ev/sdd2 >>>>>>> as a btrfs with 2 devices? >>>>>>> mkfs.btrfs /dev/sde2 /dev/sdd2 >>>>>> >>>>>> Btrfs already supports metadata mirroring when the data is strip= ed. What this >>>>>> means, is while the performance should be more-or-less identical= to MD RAID0 >>>>>> (if it isn't it's a bug), your data is a bit more secure as the = metadata >>>>>> describing it resides on both drives. Later on it will be possib= le to selct >>>>>> which directories/files should have what level of redundancy. Th= is will allow >>>>>> to have ~/work RAID1-ed and ~/videos RAID0-ed while keeping both= directories >>>>>> on the same partition and filesystem. >>>>>> >>>>>>> On a sidenote: >>>>>>> If I decide to go for raid5 which is not supported currently fr= om mkfs >>>>>>> I have to use the mdadm tool anyway, right? >>>>>> >>>>>> yes, RAID5 code is not in trunk yet. >>>>>> >>>>>> -- >>>>>> Hubert Kario >>>>>> QBS - Quality Business Software >>>>>> 02-656 Warszawa, ul. Ksawer=F3w 30/85 >>>>>> tel. +48 (22) 646-61-51, 646-74-24 >>>>>> www.qbs.com.pl >>>>>> >>>>> >>>>> >>>>> >>>>> -- >>>>> Caution: breathing may be hazardous to your health. >>>>> -- >>>>> To unsubscribe from this list: send the line "unsubscribe linux-b= trfs" in >>>>> the body of a message to majordomo@vger.kernel.org >>>>> More majordomo info at =A0http://vger.kernel.org/majordomo-info.h= tml >>>>> >>>> >>>> Regards, >>>> Sebastian J. >>>> >>>> PS. Please try to bottom-post rather than top-post. Here's a link = I >>>> can advise reading for a clarification on why bottom posting is >>>> essential: http://www.caliburn.nl/topposting.html >>>> >>> Thanks for the heads up about bottom-posting. >>> >>> >>> -- >>> Caution: breathing may be hazardous to your health. >>> >> >> It seems odd that you are reaching 100% CPU usage. Maybe it's becaus= e >> I am on an Intel processor with the integrated crc32c module, but wi= th >> metadata and data striping on 2 decent desktop drives (60 MB/s in av= g >> each on large reads), I don't go much anywhere near 10% CPU usage, a= nd >> I have compress-force enabled. I've never tried a stress test iozone= , >> but if I can still remember it, I will try to run it once I get back >> from holidays. Sorry that it doesn't help your problem, but it seems >> like it's something else. > > I really doubt my old Opteron has SSE 4.2 and as mentioned from other > users it makes a huge difference. >> >> I'm assuming you're running the nForce4 chipset. I don't recall it >> being there, but is there an AHCI option for S-ATA in the BIOS, rath= er >> than legacy or PATA mode, or something in the lines of that? That >> could in theory reduce CPU usage somewhat, but shouldn't really affe= ct >> anything before very high transfer speeds. >> > Yes it's an nForce4 chipset (DFI Expert) > And if I recall it's SATA+PATA mode enabled on mine now. > I can't be sure since I am working on it from ssh. > >> And yes, you are bottlenecked if you're running at max CPU usage. I >> would try disabling the compress mount option if the above does not >> help. > After disabling the compress and done the test again it affected the = write speed > and my CPU wasn't topped up all the time something like 80-90% > results with iozone > =A0 =A0 =A0 =A0KB =A0 reclen =A0 =A0 write =A0 rewrite =A0 =A0 =A0 re= ad =A0 =A0 reread > 8388608 =A0 =A01024 =A0147736 =A0147062 =A0 135427 =A0 134744 > > thanks for that I am trying to get the best ration from CPU usage and performance I found out that 2 SATA devices or 2 SATA and 1 ATA devices does not make a lot of difference in performance point of view but some in CPU usage The iozone results for 2 sata devices with compress are KB reclen write rewrite read reread 8388608 1024 138133 135645 166751 164077 and the cpu average topped up at ~100% Avg: 0.2% sy: 76.9% ni: 0.0% hi: 0.0% sy: 1.4% wa: 18.6% On a side note what are the differences of sy: and wa: cpu on cpu usage= ? Because on 2 sata + 1 ata the sy value was almost all time under 20% and wa value was topped till ~85% What is better? from cpu usage point of view? =46rom performance point of view I would probably keep something that gives me around ~130mb/sec write and ~140mb/sec >> >> Regards, >> Sebastian J. >> > > The next step is remove the ATA drive and test again with and without > compress mount. > > > -- > Caution: breathing may be hazardous to your health. > --=20 Caution: breathing may be hazardous to your health. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" = in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html