I'll have to reboot to double check that this is specific to the above
kernel version, but It seems something is either wrong with my
particular kernel config for raid0, or my raid0 is setup wrong.
my raid0 uses 64k chunk sizes on an ext3 fs that's 367GB large, (across
two identical sata disks on nforce4 chipset)
I have partitions on both drives of equal size (2 altogether) that are
outside of the raid0. I dbenched those partitions, the raid0 device,
and libata pata devices i also have (same rpm, less cache, same company).
pata disk : 403MB/sec
sata disk 1: 446MB/sec
raid0 : between 336MB/sec and 386MB/sec
now the sata disks alone, get 446MB/sec, but the raid device that's
comprised of them is getting >60MB/sec less throughput.
This difference is much more drastic when say only 1 process is used
with dbench,
sata disk 1: 230MB/sec
raid0 : 96MB/sec
Something definitely feels wrong with these numbers.
All filesystems are ext3, on an athlon 64 x2 system, during each test no
other io was performed, there is no swap and no other cpu intensive
operations were going on.
the filesystems were all created the same way, and all have the same
blocksizes and such. All are mounted with default options too.
On Tue, 24 Jan 2006 18:27:53 -0500, Ed Sweetman <[email protected]> wrote:
> I'll have to reboot to double check that this is specific to the above
> kernel version, but It seems something is either wrong with my
> particular kernel config for raid0, or my raid0 is setup wrong.
>
> my raid0 uses 64k chunk sizes on an ext3 fs that's 367GB large, (across
> two identical sata disks on nforce4 chipset)
>
> I have partitions on both drives of equal size (2 altogether) that are
> outside of the raid0. I dbenched those partitions, the raid0 device,
> and libata pata devices i also have (same rpm, less cache, same company).
>
> pata disk : 403MB/sec
> sata disk 1: 446MB/sec
> raid0 : between 336MB/sec and 386MB/sec
>
Uh ? I want some of those disks....
How are you measuring that ?
Some more real numbers.
A SATA raid5:
nada:~# lsscsi
[1:0:0:0] disk ATA Maxtor 7Y250M0 YAR5 -
[2:0:0:0] disk ATA Maxtor 7Y250M0 YAR5 -
[3:0:0:0] disk ATA Maxtor 7Y250M0 YAR5 -
[4:0:0:0] disk ATA Maxtor 7Y250M0 YAR5 -
[5:0:0:0] disk ATA Maxtor 7Y250M0 YAR5 -
[6:0:0:0] disk ATA Maxtor 7Y250M0 YAR5 -
[7:0:0:0] disk ATA Maxtor 7Y250M0 YAR5 -
nada:~# hdparm -t /dev/sdb /dev/sdc
/dev/sdb:
Timing buffered disk reads: 156 MB in 3.02 seconds = 51.70 MB/sec
/dev/sdc:
Timing buffered disk reads: 154 MB in 3.02 seconds = 50.96 MB/sec
nada:~# hdparm -t /dev/md0
/dev/md0:
Timing buffered disk reads: 148 MB in 3.01 seconds = 49.20 MB/sec
An SCSI raid0 one (160 and 320 mixed...)
annwn:~# hdparm -t /dev/sdc /dev/sdb
/dev/sdc:
Timing buffered disk reads: 226 MB in 3.02 seconds = 74.72 MB/sec
/dev/sdb:
Timing buffered disk reads: 122 MB in 3.00 seconds = 40.64 MB/sec
annwn:~# hdparm -t /dev/md0
/dev/md0:
Timing buffered disk reads: 242 MB in 3.00 seconds = 80.62 MB/sec
> now the sata disks alone, get 446MB/sec, but the raid device that's
> comprised of them is getting >60MB/sec less throughput.
>
> This difference is much more drastic when say only 1 process is used
> with dbench,
>
> sata disk 1: 230MB/sec
> raid0 : 96MB/sec
>
>
> Something definitely feels wrong with these numbers.
>
> All filesystems are ext3, on an athlon 64 x2 system, during each test no
> other io was performed, there is no swap and no other cpu intensive
> operations were going on.
>
> the filesystems were all created the same way, and all have the same
> blocksizes and such. All are mounted with default options too.
> -
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> the body of a message to [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
--
J.A. Magallon <jamagallon()able!es> \ Software is like sex:
werewolf!able!es \ It's better when it's free
Mandriva Linux release 2006.1 (Cooker) for i586
Linux 2.6.15-jam5 (gcc 4.0.2 (4.0.2-1mdk for Mandriva Linux release 2006.1))
J.A. Magallon wrote:
>On Tue, 24 Jan 2006 18:27:53 -0500, Ed Sweetman <[email protected]> wrote:
>
>
>
>>I'll have to reboot to double check that this is specific to the above
>>kernel version, but It seems something is either wrong with my
>>particular kernel config for raid0, or my raid0 is setup wrong.
>>
>>my raid0 uses 64k chunk sizes on an ext3 fs that's 367GB large, (across
>>two identical sata disks on nforce4 chipset)
>>
>>I have partitions on both drives of equal size (2 altogether) that are
>>outside of the raid0. I dbenched those partitions, the raid0 device,
>>and libata pata devices i also have (same rpm, less cache, same company).
>>
>>pata disk : 403MB/sec
>>sata disk 1: 446MB/sec
>>raid0 : between 336MB/sec and 386MB/sec
>>
>>
>>
>
>Uh ? I want some of those disks....
>How are you measuring that ?
>
>Some more real numbers.
>
>A SATA raid5:
>nada:~# lsscsi
>[1:0:0:0] disk ATA Maxtor 7Y250M0 YAR5 -
>[2:0:0:0] disk ATA Maxtor 7Y250M0 YAR5 -
>[3:0:0:0] disk ATA Maxtor 7Y250M0 YAR5 -
>[4:0:0:0] disk ATA Maxtor 7Y250M0 YAR5 -
>[5:0:0:0] disk ATA Maxtor 7Y250M0 YAR5 -
>[6:0:0:0] disk ATA Maxtor 7Y250M0 YAR5 -
>[7:0:0:0] disk ATA Maxtor 7Y250M0 YAR5 -
>nada:~# hdparm -t /dev/sdb /dev/sdc
>
>/dev/sdb:
> Timing buffered disk reads: 156 MB in 3.02 seconds = 51.70 MB/sec
>
>/dev/sdc:
> Timing buffered disk reads: 154 MB in 3.02 seconds = 50.96 MB/sec
>
>nada:~# hdparm -t /dev/md0
>
>/dev/md0:
> Timing buffered disk reads: 148 MB in 3.01 seconds = 49.20 MB/sec
>
>An SCSI raid0 one (160 and 320 mixed...)
>
>annwn:~# hdparm -t /dev/sdc /dev/sdb
>
>/dev/sdc:
> Timing buffered disk reads: 226 MB in 3.02 seconds = 74.72 MB/sec
>
>/dev/sdb:
> Timing buffered disk reads: 122 MB in 3.00 seconds = 40.64 MB/sec
>
>annwn:~# hdparm -t /dev/md0
>
>/dev/md0:
> Timing buffered disk reads: 242 MB in 3.00 seconds = 80.62 MB/sec
>
>
I was using dbench with three threads. In retrospect, I am pretty sure
my 2GB of ram was creating that performance. Though, the poor
performance when run on the raid0 device still stands.
This performance hit doesn't exist when using hdparm to test the
bandwidth of the devices
/dev/sdc:
Timing buffered disk reads: 166 MB in 3.01 seconds = 55.19 MB/sec
psuedomode:/mnt# hdparm -t /dev/sda
/dev/sda:
Timing buffered disk reads: 126 MB in 3.02 seconds = 41.72 MB/sec
psuedomode:/mnt# hdparm -t /dev/md0
/dev/md0:
Timing buffered disk reads: 338 MB in 3.02 seconds = 112.07 MB/sec
sda is pata libata
sdc is sata libata
md0 is two identical sata libata devices (sdc and sdd) in RAID0
So apparently, this may be filesystem related, as it pertains to being
in a raid setup (since the filesystems are all the same otherwise except
size).
>
>
>>now the sata disks alone, get 446MB/sec, but the raid device that's
>>comprised of them is getting >60MB/sec less throughput.
>>
>>This difference is much more drastic when say only 1 process is used
>>with dbench,
>>
>>sata disk 1: 230MB/sec
>>raid0 : 96MB/sec
>>
>>
>>Something definitely feels wrong with these numbers.
>>
>>All filesystems are ext3, on an athlon 64 x2 system, during each test no
>>other io was performed, there is no swap and no other cpu intensive
>>operations were going on.
>>
>>the filesystems were all created the same way, and all have the same
>>blocksizes and such. All are mounted with default options too.
>>-
>>
>>
On 1/25/06, Ed Sweetman <[email protected]> wrote:
> I'll have to reboot to double check that this is specific to the above
> kernel version, but It seems something is either wrong with my
> particular kernel config for raid0, or my raid0 is setup wrong.
>
> my raid0 uses 64k chunk sizes on an ext3 fs that's 367GB large, (across
> two identical sata disks on nforce4 chipset)
>
> I have partitions on both drives of equal size (2 altogether) that are
> outside of the raid0. I dbenched those partitions, the raid0 device,
> and libata pata devices i also have (same rpm, less cache, same company).
>
> pata disk : 403MB/sec
> sata disk 1: 446MB/sec
> raid0 : between 336MB/sec and 386MB/sec
Hmm, looks optimistic, I performed some raid0, raid1 testing on SATA recently
here: http://bugsplatter.mine.nu/test/raid_times
Grant.