[Lustre-discuss] drbd slow I/O with lustre filesystem

[Jake Maul]

Actually now that I think about it, I think the sync speed is for
*rebuilds*, and actually subtracts from available bandwidth usable for
normal replication. So if you're saturating your disk or network with
the rebuild syncer, you won't have much available performance for
normal replication. The DRBD documentation has a rule of thumb... I
think it's 1/3rd of your bandwidth for the syncer.

Jake

On Thu, Oct 1, 2009 at 7:50 PM, Jake Maul <jakemaul at gmail.com> wrote:
> Just a guess, but possibly the DRBD syncer speed is too low? I forget
> the syntax, but it's in the manual... it can be set in drbd.conf or on
> the command line... or maybe you're using a different sync method now
> than before (async -> sync)? Those are the first two things that come
> to my mind.
>
> Jake
>
> On Wed, Sep 30, 2009 at 7:23 PM, Dam Thanh Tung <tungdt at isds.vn> wrote:
>> Problems followed by problems, sorry if i am about to be a spammer in this
>> mailing list :)
>>
>> I'm currently using drbd as a raid 1 network devices solution for my lustre
>> storage system. It worked well during 3 months but now, when i have to
>> reformat our devices, re-synchronize drbd devices ( it took about 2 days
>> with 6TB raid-5 partition ). After formatting them with lustre format (
>> using mkfs.lustre ) , i start to copy data to my drbd devices, but:
>>
>> - Its I/O wait when i monitor by top or iostat is too hight, about 25%
>>
>> - The copy speed from my web client to our OST using drbd devices is too
>> low, only about 13MB/s although client and ost in is the same 1Gb Ethernet
>> LAN.
>>
>>
>> When i tried using one OST without drbd, it worked quite well
>>
>> So, could any one please tell me where the problem is ? In our drbd devices
>> or because of lustre ? Is there anyone has the same problem with me ? :(
>>
>>
>>
>> _______________________________________________
>> Lustre-discuss mailing list
>> Lustre-discuss at lists.lustre.org
>> http://lists.lustre.org/mailman/listinfo/lustre-discuss
>>
>>
>