From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hubert Kario Subject: Re: Raid0 with btrfs Date: Sat, 7 Aug 2010 01:02:20 +0200 Message-ID: <201008070102.20580.hka@qbs.com.pl> References: Mime-Version: 1.0 Content-Type: Text/Plain; charset=iso-8859-1 Cc: "Sebastian 'gonX' Jensen" , linux-btrfs@vger.kernel.org To: Leonidas Spyropoulos Return-path: In-Reply-To: List-ID: On Saturday 07 of August 2010 00:24:08 Leonidas Spyropoulos wrote: > On Fri, Aug 6, 2010 at 7:32 PM, Sebastian 'gonX' Jensen >=20 > 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 mdadm > >> mkfs.btrfs supports that or needs to be 83 (Linux) ? > >=20 > > FD is for mdraid integrated into the Linux kernel. I have mine at 8= 3. > > It won't hurt to have them at FD, but the kernel will spend extra t= ime > > as it probes the devices on boot, causing a slight slowdown. >=20 > 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 >=20 > 2 SATA and 1 ATA drive > I thought that ATA will bottleneck the other 2 drives but seems like = 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): > KB reclen write rewrite read reread > 8388608 1024 134869 139607 229146 228800 > 8388608 1024 135151 139050 233461 235929 >=20 > The above is with -o compress option enabled and my cpu topped up on > 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 Considering you have 100% CPU usage during the test, it would seem so. >=20 > >> On Thu, Aug 5, 2010 at 3:40 PM, Hubert Kario wrot= e: > >>> On Thursday 05 August 2010 16:15:22 Leonidas Spyropoulos wrote: > >>>> Hi all, > >>>>=20 > >>>> 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 configur= ation > >>>> of mdadm and just format the /dev/md0 device as btrfs OR > >>>> delete the raid device and format the 2 partitions /dev/sde2 /de= v/sdd2 > >>>> as a btrfs with 2 devices? > >>>> mkfs.btrfs /dev/sde2 /dev/sdd2 > >>>=20 > >>> Btrfs already supports metadata mirroring when the data is stripe= d. > >>> 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 bi= t > >>> more secure as the metadata describing it resides on both drives. > >>> Later on it will be possible to selct which directories/files sho= uld > >>> have what level of redundancy. This will allow to have ~/work RAI= D1-ed > >>> and ~/videos RAID0-ed while keeping both directories on the same > >>> partition and filesystem. > >>>=20 > >>>> On a sidenote: > >>>> If I decide to go for raid5 which is not supported currently fro= m mkfs > >>>> I have to use the mdadm tool anyway, right? > >>>=20 > >>> yes, RAID5 code is not in trunk yet. > >>>=20 > >>> -- > >>> 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 > >>=20 > >> -- > >> Caution: breathing may be hazardous to your health. > >> -- > >> To unsubscribe from this list: send the line "unsubscribe linux-bt= rfs" > >> in the body of a message to majordomo@vger.kernel.org > >> More majordomo info at http://vger.kernel.org/majordomo-info.html > >=20 > > Regards, > > Sebastian J. > >=20 > > 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 >=20 > Thanks for the heads up about bottom-posting. --=20 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 -- 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