Do we need to consider the chunk size when we adjust the value of
Striped_Cache_Szie for the MD-RAID5 array?
Liang
----- Original Message -----
From: "Justin Piszcz" <[email protected]>
To: "kyle" <[email protected]>
Cc: <[email protected]>; <[email protected]>
Sent: Monday, January 22, 2007 5:18 AM
Subject: Re: change strip_cache_size freeze the whole raid
>
>
> On Mon, 22 Jan 2007, kyle wrote:
>
>> Hi,
>>
>> Yesterday I tried to increase the value of strip_cache_size to see if I
>> can
>> get better performance or not. I increase the value from 2048 to
>> something
>> like 16384. After I did that, the raid5 freeze. Any proccess read / write
>> to
>> it stucked at D state. I tried to change it back to 2048, read
>> strip_cache_active, cat /proc/mdstat, mdadm stop, etc. All didn't return
>> back.
>> I even cannot shutdown the machine. Finally I need to press the reset
>> button
>> in order to get back my control.
>>
>> Kernel is 2.6.17.8 x86-64, running at AMD Athlon3000+, 2GB Ram, 8 x
>> Seagate
>> 8200.10 250GB HDD, nvidia chipset.
>>
>> cat /proc/mdstat (after reboot):
>> Personalities : [raid1] [raid5] [raid4]
>> md1 : active raid1 hdc2[1] hda2[0]
>> 6144768 blocks [2/2] [UU]
>>
>> md2 : active raid5 sdf1[7] sde1[6] sdd1[5] sdc1[4] sdb1[3] sda1[2]
>> hdc4[1]
>> hda4[0]
>> 1664893440 blocks level 5, 512k chunk, algorithm 2 [8/8] [UUUUUUUU]
>>
>> md0 : active raid1 hdc1[1] hda1[0]
>> 104320 blocks [2/2] [UU]
>>
>> Kyle
>>
>> -
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>
> Yes, I noticed this bug too, if you change it too many times or change it
> at the 'wrong' time, it hangs up when you echo numbr >
> /proc/stripe_cache_size.
>
> Basically don't run it more than once and don't run it at the 'wrong' time
> and it works. Not sure where the bug lies, but yeah I've seen that on 3
> different machines!
>
> Justin.
>
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>