the resync is going on. I've already test each disk individually and I get
38MB/sec. The machine is a 2,.4 GHz xeon with 2GB ram so there should
be no problem with cpu or memory. Before I tried raid5 i made an 8xraid0
stripe which yielded ~120MB/sec which is what I'd expect from the controller.
So there is no way to initialize the raid5 device - similar to what a hardware raid
controller does?
p
Guy wrote:
You don't need to wait. You can use the array now.
But ouch 305K/sec! If this a 386-33? :)
Have you tried dd tests on each disk to verify each works well?
Something like: time dd if=/dev/sdc1 of=/dev/null bs=64k count=100000 This is just a read test. My disks take about 340 seconds. Yours should be about twice as fast.
Each disk should give about the same performance. You may find 1 that has issues.
If you are willing to re-build the array, you could do a write test: time dd if=/dev/zero of=/dev/sdc1 bs=64k count=10000 THIS WILL TRASH THE ARRAY!!!
Guy
-----Original Message----- From: linux-raid-owner@xxxxxxxxxxxxxxx [mailto:linux-raid-owner@xxxxxxxxxxxxxxx] On Behalf Of PAulN Sent: Thursday, August 19, 2004 1:53 PM To: Guy Cc: linux-raid@xxxxxxxxxxxxxxx Subject: Re: Raid5 Construction Question
Guy, thanks for the snappy reply! I wish my disks were as fast :) I failed to mention that I had been tweaking those proc values. Currently they are: (root@lcn0:raid)# cat speed_limit_max 200000 (root@lcn0:raid)# cat speed_limit_min 10000
If I'm correct, this means that the min speed is 10MB/sec per device.
I've verified that each device has a seq write speed of about 38MB/sec so
each should be capable of handling 10,000Kbytes sec. Right after I issue
a raidstart the speed is pretty good (~30MB/sec) but is just falls until it hits
around 300K.
md0 : active raid5 sdh1[7] sdf1[6] sdg1[5] sde1[4] sdd1[3] sdc1[2] sdb1[1] sda1[0]
481949184 blocks level 5, 64k chunk, algorithm 2 [7/7] [UUUUUUU]
[>....................] resync = 2.4% (1936280/80324864) finish=4261.4min speed=305K/sec
In the docs I saw that "reconstruction" is possible with raidhotadd but I didn't
see anything about initialization. So am I "screwed" until the resync is fixed? I was depeding
on the disks to do some filesystem testing but maybe I'll have to wait a few days.. Thanks,
Paul
Guy wrote:
In short... Issue this command: echo 100000 > /proc/sys/dev/raid/speed_limit_max
If it does not help issue this command and send the results: cat /proc/mdstat
Details below.
These are related to throttling: /proc/sys/dev/raid/speed_limit_max /proc/sys/dev/raid/speed_limit_min
Do "man md" for more info.
The speed limits are per device, not per array. Make sure the max is large enough the permit your disks to go as fast as they can. I use 100000 (100,000K bytes/second). My disks are not that fast, and having too large of a number does not hurt. At least as a test, set the min to the same value as max.
I use these commands when I want to change by hand: cat /proc/sys/dev/raid/speed_limit_max cat /proc/sys/dev/raid/speed_limit_min
echo 100000 > /proc/sys/dev/raid/speed_limit_max echo 1000 > /proc/sys/dev/raid/speed_limit_min
Guy
-----Original Message----- From: linux-raid-owner@xxxxxxxxxxxxxxx [mailto:linux-raid-owner@xxxxxxxxxxxxxxx] On Behalf Of PAulN Sent: Thursday, August 19, 2004 1:25 PM To: linux-raid@xxxxxxxxxxxxxxx Subject: Raid5 Construction Question
Hi,
So I have a raid 5 which is around ~1TB and the problem I've been having is that
the resync rate is really bad. This is understandable given that the raid5 has not
been initialized. Does anyone know a way for me to initialize my raid5 before I use it so
that the resync process doesn't run for 3 days?
thanks
paul
Config: ------------------------------------------------- raiddev /dev/md0 raid-level 5 nr-raid-disks 7 nr-spare-disks 1 chunk-size 64k persistent-superblock 1 parity-algorithm left-symmetric device /dev/sda1 raid-disk 0 device /dev/sdb1 raid-disk 1 device /dev/sdc1 raid-disk 2 device /dev/sdd1 raid-disk 3 device /dev/sde1 raid-disk 4 device /dev/sdg1 raid-disk 5 device /dev/sdf1 raid-disk 6 device /dev/sdh1 spare-disk 0 ----------------------------------------
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