[mythtv-users] Software RAID and ionice
Richard Freeman
r-mythtv at thefreemanclan.net
Wed May 23 01:17:39 UTC 2007
David Rees wrote:
> On 5/22/07, Richard Freeman <r-mythtv at thefreemanclan.net> wrote:
>> The raid5 works just fine for mythbackend when the system isn't busy
>> writing to the same disk.
>
> Which indicates a bottleneck somewhere. ext3 is notorious for blocking
> writes when the journal is flushing which kills performance. Did you
> create the filesystem with the stride option? How big are the stripes
> in your raid array? How many disks and how fast are they?
>
I answered most of your questions in my other email, but I neglected these.
I did read about the stride option. I think I have that set
appropriately. I forget what I set it to, however... I think it was
probably 32 (64K stripe / 4K blocks).
Here is the info for the raid itself - let me know if there is anything
else that would be of use...:
/dev/md3:
Version : 00.90.03
Creation Time : Tue Apr 24 21:22:44 2007
Raid Level : raid5
Array Size : 485885696 (463.38 GiB 497.55 GB)
Used Dev Size : 242942848 (231.69 GiB 248.77 GB)
Raid Devices : 3
Total Devices : 3
Preferred Minor : 3
Persistence : Superblock is persistent
Intent Bitmap : Internal
Update Time : Tue May 22 21:02:50 2007
State : active
Active Devices : 3
Working Devices : 3
Failed Devices : 0
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 64K
UUID : 655984a8:07fe58b4:301f0b57:926cce87
Events : 0.580
Number Major Minor RaidDevice State
0 8 19 0 active sync /dev/sdb3
1 8 35 1 active sync /dev/sdc3
2 8 3 2 active sync /dev/sda3
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