[CentOS] ext4 in CentOS 5.6?

[Rudi Ahlers]

On Tue, Jul 5, 2011 at 4:46 PM, Christopher Chan
<christopher.chan at bradbury.edu.hk> wrote:
>> We've been running ZFS on a few storage servers, both in the office and
>> for our hosting clients for about 2 years now and all I can say it that
>> it's rock solid.
>
> +1
>
> Although I have seen screams from others on the opensolaris/openindiana
> lists I personally have not experienced them.

True, but that you'll get in any industry, with any product - even EMC
or other similar large and expensive equipment vendors :)

>> With raidz2 (similar to RAID6) we've never had any data loss or
>> corruption due to hard drive failure and long rebuilds.
>> And if you use SSD for ZIL & LARC2 cache, it's super fast. the same
>> systems with EXT3 simply couldn't match the performance we got got from
>> ZFS.
>>
>
> I take it you limit your raidz2 arrays to a maximum of 9 drives?

Yes, in a 12-bay chassis, we use:
1x L2ARC SSD
2x ZIL SSD mirrored
9x SATA / SAS (depending on application) drives in raidz2, which
effectively gives us 7 usable drives

I am contemplating using 24bay chassis instead, purely from a cost
(hardware, power, cooling) point of view and then using 2x raidz2
pools.

>
> /me wonders what an md raid array with an ext3 fs that has its journal
> on an ssd in full data journal mode give in terms of performance.

I honestly haven't tried this yet, probably cause when I looked at how
this works, it's only the journal which runs on SSD, so reads won't
benefit much from it, only reads. But with ZFS you get all the data,
read & write, cached on SSD


>
> I would not give zfs the performance crown just yet. Have you tried
> using ext3 with an external journal on the ssd and ext3 on raid6? What
> kind of usage pattern do you have on those zfs filesystems?

It's generally shared & VPS hosting, so basically: websites, email,
databases, logs, etc :)


>
>>
>>
>> BUT, since we're not allowed to talk about anything else other than
>> CentOS on this list people don't mention it.
>>
>
> I find that this list is generally tolerant of offtopic but technical
> topics. What it does not like is flamewars made of posts that have zero
> technical merit.

True, but have you seen how quickly some "grumpy mailing list
activist" can derail a thread with: "please don't post OT stuff here"
and then the whole conversation just dies down......




-- 
Kind Regards
Rudi Ahlers
SoftDux

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