Using SDs for caching?

Using SDs for caching?

[Roy Sigurd Karlsbakk]

Hi all

I have heard/read about systems from Sun and NetApp using SDs for =20
caching. Sun uses different SDs for read and write caching (one being =20
faster for reads and the other for writes). The storage solution from =20
Sun is based on Solaris with ZFS.

I know too little about filesystems design to know exactly how they do =
=20
this, but can someone think of a way this could be implemented in =20
btrfs? I would think such a cache level could speed up things rather =20
well.

Best regards

roy
--
Roy Sigurd Karlsbakk
(+47) 97542685
roy@karlsbakk.net
http://blogg.karlsbakk.net/
--
I all pedagogikk er det essensielt at pensum presenteres =20
intelligibelt. Det er et element=E6rt imperativ for alle pedagoger =E5 =
=20
unng=E5 eksessiv anvendelse av idiomer med fremmed opprinnelse. I de =20
fleste tilfeller eksisterer adekvate og relevante synonymer p=E5 norsk.

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Re: Using SSDs for caching?

[Roy Sigurd Karlsbakk]

On 18. juni. 2009, at 15.56, Roy Sigurd Karlsbakk wrote:

> Hi all
>
> I have heard/read about systems from Sun and NetApp using SDs for =20
> caching. Sun uses different SDs for read and write caching (one =20
> being faster for reads and the other for writes). The storage =20
> solution from Sun is based on Solaris with ZFS.
>
> I know too little about filesystems design to know exactly how they =20
> do this, but can someone think of a way this could be implemented in =
=20
> btrfs? I would think such a cache level could speed up things rather =
=20
> well.


erm. Obviously, I meant Solid State Drives, SSDs. Sorry about this.

roy
--
Roy Sigurd Karlsbakk
(+47) 97542685
roy@karlsbakk.net
http://blogg.karlsbakk.net/
--
I all pedagogikk er det essensielt at pensum presenteres =20
intelligibelt. Det er et element=E6rt imperativ for alle pedagoger =E5 =
=20
unng=E5 eksessiv anvendelse av idiomer med fremmed opprinnelse. I de =20
fleste tilfeller eksisterer adekvate og relevante synonymer p=E5 norsk.

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Re: Using SSDs for caching?

[Tomasz Torcz]

On Thu, Jun 18, 2009 at 03:56:23PM +0200, Roy Sigurd Karlsbakk wrote:
> I have heard/read about systems from Sun and NetApp using SDs for =20
> caching. Sun uses different SDs for read and write caching (one being=
 =20
> faster for reads and the other for writes). The storage solution from=
 =20
> Sun is based on Solaris with ZFS.
>
> I know too little about filesystems design to know exactly how they d=
o =20
> this, but can someone think of a way this could be implemented in btr=
fs?=20

  Linux already has second-level=C2=B9 cache layer, it called FS-Cache.=
 For now,
the sole user is NFS. btrfs could take advantage of FS-Cache also.

=C2=B9 first-level is page cache in RAM

--=20
Tomasz Torcz               "Never underestimate the bandwidth of a stat=
ion
xmpp: zdzichubg@chrome.pl    wagon filled with backup tapes." -- Jim Gr=
ay

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Re: Using SSDs for caching?

[Roy Sigurd Karlsbakk]

On 18. juni. 2009, at 17.55, Tomasz Torcz wrote:

> On Thu, Jun 18, 2009 at 03:56:23PM +0200, Roy Sigurd Karlsbakk wrote:
>> I have heard/read about systems from Sun and NetApp using SDs for
>> caching. Sun uses different SDs for read and write caching (one bein=
g
>> faster for reads and the other for writes). The storage solution fro=
m
>> Sun is based on Solaris with ZFS.
>>
>> I know too little about filesystems design to know exactly how they =
=20
>> do
>> this, but can someone think of a way this could be implemented in =20
>> btrfs?
>
>  Linux already has second-level=B9 cache layer, it called FS-Cache. =20
> For now,
> the sole user is NFS. btrfs could take advantage of FS-Cache also.


I googled around a bit for this, but couldn't find anything useful. =20
Where can I find anything about this second (or fifth) level caching?

roy
--
Roy Sigurd Karlsbakk
(+47) 97542685
roy@karlsbakk.net
http://blogg.karlsbakk.net/
--
I all pedagogikk er det essensielt at pensum presenteres =20
intelligibelt. Det er et element=E6rt imperativ for alle pedagoger =E5 =
=20
unng=E5 eksessiv anvendelse av idiomer med fremmed opprinnelse. I de =20
fleste tilfeller eksisterer adekvate og relevante synonymer p=E5 norsk.

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Re: Using SSDs for caching?

[hu.taoo]

On Thu, Jun 18, 2009 at 07:25:46PM +0200, Roy Sigurd Karlsbakk wrote:
> On 18. juni. 2009, at 17.55, Tomasz Torcz wrote:
> 
> > On Thu, Jun 18, 2009 at 03:56:23PM +0200, Roy Sigurd Karlsbakk wrote:
> >> I have heard/read about systems from Sun and NetApp using SDs for
> >> caching. Sun uses different SDs for read and write caching (one being
> >> faster for reads and the other for writes). The storage solution from
> >> Sun is based on Solaris with ZFS.
> >>
> >> I know too little about filesystems design to know exactly how they  
> >> do
> >> this, but can someone think of a way this could be implemented in  
> >> btrfs?
> >
> >  Linux already has second-level? cache layer, it called FS-Cache.  
> > For now,
> > the sole user is NFS. btrfs could take advantage of FS-Cache also.
> 
> 
> I googled around a bit for this, but couldn't find anything useful.  
> Where can I find anything about this second (or fifth) level caching?

Will this help? http://www.linux-mag.com/cache/7378/1.html

Re: Using SSDs for caching?

[Sébastien Wacquiez]

Tomasz Torcz a =C3=A9crit :
>   Linux already has second-level=C2=B9 cache layer, it called FS-Cach=
e. For now,
> the sole user is NFS. btrfs could take advantage of FS-Cache also.
>
> =C2=B9 first-level is page cache in RAM
>  =20

=46S-Cache is a good thing to speedup your network filesystem, but to b=
e=20
efficient localy, IMHO, the second-level cache shoud be at the block le=
vel.

So it should go directly in btrfs or in something like the device mappe=
r ...



S=C3=A9bastien Wacquiez
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