Date: Wed, 29 Aug 2012 08:49:37 +0300 From: Nikolay Denev <ndenev@gmail.com> To: Andrew Young <ayoung@mosaicarchive.com> Cc: Josh Paetzel <josh@tcbug.org>, "freebsd-hardware@freebsd.org" <freebsd-hardware@freebsd.org> Subject: Re: Support for Fusion IO drives? Message-ID: <4D5E46B8-B1C5-4131-BEB3-673769B844E7@gmail.com> In-Reply-To: <3F6C1EB2-1EC4-4863-A5BF-093649D9D61C@mosaicarchive.com> References: <CAHMRaQerwM4FRnfkc-1Yaa7JUVjJJazDhhQ_JZzE_Wn5OzKL2Q@mail.gmail.com> <503D3026.6010901@ixsystems.com> <CAK6u07XeH%2BjTg2M4s%2BpP=-HNgmtNC==Bh4fbZqCVWo5O7_rbyg@mail.gmail.com> <503D4F48.9020108@tcbug.org> <3F6C1EB2-1EC4-4863-A5BF-093649D9D61C@mosaicarchive.com>
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Fron the zpool man page:
By default, the intent log is allocated from blocks within the main =
pool.
However, it might be possible to get better performance using =
separate
intent log devices such as NVRAM or a dedicated disk.
I was also contemplating the idea of a fast SSD on PCIe as a ZIL and =
L2ARC.
And given the fact that the SSD will not suffer from the different types =
and locations of IO requests,
maybe it makes sense to go with a big SSD, and partition it for a small =
ZIL partition,
and the rest for L2ARC. Anyone tried that?
Regards,
Nikolay
On Aug 29, 2012, at 2:47 AM, Andrew Young <ayoung@mosaicarchive.com> =
wrote:
> Thanks for the great feedback Josh! The optimum size for an ssd zil =
device was still an open question for us. I'm really glad to hear that =
they don't need to be that big.
>=20
> What does zfs do with the zil if there is no dedicated zil device? Our =
servers consist of a small sata drive that holds the OS and a boatload =
of larger drives on a sas bus. What I'm wondering is if I simply replace =
the OS disk with an ssd will I get the same performance boost as if I =
added a dedicated ssd zil?=20
>=20
> Thanks!
> Andy
>=20
> On Aug 28, 2012, at 7:07 PM, Josh Paetzel <josh@tcbug.org> wrote:
>=20
>>>> -------- Original Message --------
>>>> Subject: Support for Fusion IO drives?
>>>> Date: Tue, 28 Aug 2012 16:46:00 -0400
>>>> From: Andy Young <ayoung@mosaicarchive.com>
>>>> To: freebsd-hardware@freebsd.org
>>>>=20
>>>>=20
>>>> We are investigating adding SSDs as ZIL devices to boost our ZFS =
write
>>>> performance. I read an article a while ago about iX Systems teaming =
up
>>>> with
>>>> Fusion IO to integrate their hardware with FreeBSD. Does anyone =
know
>>>> anything about supported drivers for Fusion IO's iodrives?
>>>>=20
>>>> Thanks!
>>>>=20
>>>> Andy
>>>> _______________________________________________
>>>> freebsd-hardware@freebsd.org mailing list
>>>> http://lists.freebsd.org/mailman/listinfo/freebsd-hardware
>>>> To unsubscribe, send any mail to
>>>> "freebsd-hardware-unsubscribe@freebsd.org"
>>>>=20
>>>>=20
>>>>=20
>>>>=20
>>=20
>> I'll put on my iXsystems hat here, as well as my fast storage, ZFS =
and
>> Fusion-I/O hat.
>>=20
>> The ZFS filesystem supports dedicated ZIL devices, which can =
accelerate
>> certain types of write requests, notably related to fsync. The =
VMWare
>> NFS client issues a sync with every write, and most databases do as
>> well. In those types of environments having a fast dedicated ZIL =
device
>> is almost essential. In other environments the benefits of a =
dedicated
>> ZIL range from non-existent to substantial.
>>=20
>> A good dedicated ZIL device is all about latency. It doesn't need to =
be
>> large, in fact it will only ever handle 10 seconds of writes, so 10x
>> network bandwidth is worst case. (In most environments this means =
20GB
>> is larger than needed).
>>=20
>> Fusion-I/O cards are far too large to be cost effective ZIL devices.
>> Even though they do rock at I/O latency, the really fast ones are =
also
>> fairly large, so the $/GB on them isn't so attractive. There are =
better
>> options for ZIL devices.
>>=20
>> Another consideration is the Fusion-I/O driver is fairly memory =
hungry,
>> which competes with memory ZFS wants to use for read caching.
>>=20
>> Now as an L2ARC device, that's a whole different can of worms.
>>=20
>> Command line used: iozone -r 4k -s 96g -i 0 -i 1 -i 2 -t 8
>> Parent sees throughput for 8 readers =3D 1712399.95 KB/sec
>> L2 ARC Breakdown: 197.45m
>> Hit Ratio: 98.61% 194.71m
>> L2 ARC Size: (Adaptive) 771.13 GiB
>> ARC Efficiency: 683.40m
>> Actual Hit Ratio: 71.09% 485.82m
>>=20
>> ~ 800GB test data, all served from cache.
>>=20
>> If you are considering Fusion-I/O, the FreeBSD driver is generally =
not
>> released to the general public by Fusion-I/O, but can be obtained =
from
>> various partners. (I believe iXsystems is the only FreeBSD friendly
>> fusion-i/o partner but could be wrong about that)
>>=20
>>=20
>> --=20
>> Thanks,
>>=20
>> Josh Paetzel
>>=20
> _______________________________________________
> freebsd-hardware@freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-hardware
> To unsubscribe, send any mail to =
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