On Fri, Aug 6, 2010 at 7:32 PM, Sebastian 'gonX' Jensen
<gonx@xxxxxxxxxxxxxxx> wrote:
> On 6 August 2010 20:23, Leonidas Spyropoulos <artafinde@xxxxxxxxx> 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) ?
>
> 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 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
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
>>
>> On Thu, Aug 5, 2010 at 3:40 PM, Hubert Kario <hka@xxxxxxxxxx> wrote:
>>> 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 configuration of
>>>> mdadm and just format the /dev/md0 device as btrfs OR
>>>> delete the raid device and format the 2 partitions /dev/sde2 /dev/sdd2
>>>> as a btrfs with 2 devices?
>>>> mkfs.btrfs /dev/sde2 /dev/sdd2
>>>
>>> Btrfs already supports metadata mirroring when the data is striped. 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 possible to selct
>>> which directories/files should have what level of redundancy. This 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 from 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. Ksawerów 30/85
>>> tel. +48 (22) 646-61-51, 646-74-24
>>> www.qbs.com.pl
>>>
>>
>>
>>
>> --
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>>
>
> 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.
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