bcache using in case of 5 hdd disks

bcache using in case of 5 hdd disks

[Vasiliy Tolstov]

Hi all.
I'm very happy with bcache on current production system (raid1 with 1
sata hdd + 1 ssd). But now i get new platform with 5 sata hdd and 1
ssd disk.
Each of sata hdd i need to format with some fs (ext4 or btrfs?) to
store data. How can i use bcache in this case? I'm unerstand that i
can create5 partitions on ssd drive and use each partition to each
drive. But does it possible to use whole ssd disk to cache in this
case?

Thanks!

-- 
Vasiliy Tolstov,
e-mail: v.tolstov@selfip.ru
jabber: vase@selfip.ru

RE: bcache using in case of 5 hdd disks

[Patrick Zwahlen]

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Hi!

> -----Original Message-----
> From: linux-bcache-owner@vger.kernel.org [mailto:linux-bcache-
> owner@vger.kernel.org] On Behalf Of Vasiliy Tolstov
> Sent: jeudi 23 janvier 2014 20:26
> To: linux-bcache@vger.kernel.org
> Subject: bcache using in case of 5 hdd disks
>
> Hi all.
> I'm very happy with bcache on current production system (raid1 with 1
> sata hdd + 1 ssd). But now i get new platform with 5 sata hdd and 1
> ssd disk.
> Each of sata hdd i need to format with some fs (ext4 or btrfs?) to
> store data. How can i use bcache in this case? I'm unerstand that i
> can create5 partitions on ssd drive and use each partition to each
> drive. But does it possible to use whole ssd disk to cache in this
> case?

My understanding is that a single "cacheset" (in your case, your SSD) can be 
shared between multiple backing devices.

You should be able to attach a single cacheset's UUID to multiple devices.

Can anyone else confirm ?

>
> Thanks!
>
> --
> Vasiliy Tolstov,
> e-mail: v.tolstov@selfip.ru
> jabber: vase@selfip.ru
> --


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Re: bcache using in case of 5 hdd disks

[Rolf Fokkens]

Op 27/01/14 21:38 schreef Patrick Zwahlen <paz@navixia.com>:

>
>My understanding is that a single "cacheset" (in your case, your SSD) can
>be 
>shared between multiple backing devices.
>
>You should be able to attach a single cacheset's UUID to multiple devices.
>
>Can anyone else confirm ?

Yep, confirmed!

Rolf

Re: bcache using in case of 5 hdd disks

[Vasiliy Tolstov]

2014-01-28 Rolf Fokkens <rolf@rolffokkens.nl>
>
> Op 27/01/14 21:38 schreef Patrick Zwahlen <paz@navixia.com>:
>
> >
> >My understanding is that a single "cacheset" (in your case, your SSD) can
> >be
> >shared between multiple backing devices.
> >
> >You should be able to attach a single cacheset's UUID to multiple devices.
> >
> >Can anyone else confirm ?
>
> Yep, confirmed!
>
> Rolf


Can you explain for me how can i do that?


-- 
Vasiliy Tolstov,
e-mail: v.tolstov@selfip.ru
jabber: vase@selfip.ru

Re: bcache using in case of 5 hdd disks

[Thierry De Leeuw]

Hi,

The documentation at 
http://evilpiepirate.org/git/linux-bcache.git/plain/Documentation/bcache.txt?h=bcache-dev 
explains how to do it.

Look at the "Getting started" and "ATTACHING" section.

Bottom line to create one cache (sdc) and 2 backing (sda and sdb) 
devices, use

make-bcache -B /dev/sda /dev/sdb -C /dev/sdc


Best regards

Thierry


On 01/28/2014 01:31 PM, Vasiliy Tolstov wrote:
> 2014-01-28 Rolf Fokkens<rolf@rolffokkens.nl>
>> Op 27/01/14 21:38 schreef Patrick Zwahlen<paz@navixia.com>:
>>
>>> My understanding is that a single "cacheset" (in your case, your SSD) can
>>> be
>>> shared between multiple backing devices.
>>>
>>> You should be able to attach a single cacheset's UUID to multiple devices.
>>>
>>> Can anyone else confirm ?
>> Yep, confirmed!
>>
>> Rolf
> Can you explain for me how can i do that?
>
>

Re: bcache using in case of 5 hdd disks

[Rolf Fokkens]

Hi,

Op 28/01/14 14:56 schreef Thierry De Leeuw <thierry@de-leeuw.org>:

>The documentation at
>http://evilpiepirate.org/git/linux-bcache.git/plain/Documentation/bcache.t
>xt?h=bcache-dev 
>explains how to do it.
>
>Look at the "Getting started" and "ATTACHING" section.
>
>Bottom line to create one cache (sdc) and 2 backing (sda and sdb)
>devices, use
>
>make-bcache -B /dev/sda /dev/sdb -C /dev/sdc

And (from the same documentation) if you¹ve created (make-bcache) and
registered the caching and backing devices separately, you can attach them
like this:

echo <CSET-UUID> > /sys/block/bcache0/bcache/attach

echo <CSET-UUID> > /sys/block/bcache1/bcache/attach


Assuming that /dev/sda and /dev/sdb have shown up as /dev/bcache0 and
/dev/bcache1 as their bcached counterparts after registering, and
<CSET-UUID> being the UUID of the cache device to be found in
/sys/fs/bcache.

Rolf

>
>
>Best regards
>
>Thierry
>
>
>On 01/28/2014 01:31 PM, Vasiliy Tolstov wrote:
>> 2014-01-28 Rolf Fokkens<rolf@rolffokkens.nl>
>>> Op 27/01/14 21:38 schreef Patrick Zwahlen<paz@navixia.com>:
>>>
>>>> My understanding is that a single "cacheset" (in your case, your SSD)
>>>>can
>>>> be
>>>> shared between multiple backing devices.
>>>>
>>>> You should be able to attach a single cacheset's UUID to multiple
>>>>devices.
>>>>
>>>> Can anyone else confirm ?
>>> Yep, confirmed!
>>>
>>> Rolf
>> Can you explain for me how can i do that?
>>
>>
>
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