Recommended sw raid setup

Recommended sw raid setup

[John Obaterspok]

Hi,

I've going to setup a _home_ file server to store all photos & family
videos, work related material, DNLA streaming and more.

The server will be set to suspend when not in use for an hour or so.

I've been thinking about buying 3 x 3 TB SATA disks and put these in
software RAID5 (except for a smaller boot partition on all three disks
which will be RAID1).

Any recommendation for what SATA drives to get? Should I get
enterprise drives that support TLER (or alike), or will the greener
low cost drives be enough, is there something in between?

Is it better to buy 4 low cost drives in RAID1 or 3 enterprise drives in RAID5?

Please help, I'm completely lost!

--john
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Re: Recommended sw raid setup

[Drew]

Hi John,

Personally I think you'd be fine with consumer grade drives. Put them
in a RAID-5 array and you should be set.

The high end consumer & enterprise stuff w/ TLER and the like is only
really needed if you put a lot of demand on the disks, running virtual
machines for example. A basic file server for home use won't stress
the drives enough to need the more expensive ones.


-Drew

On 07/02/2011, John Obaterspok <john.obaterspok@gmail.com> wrote:
> Hi,
>
> I've going to setup a _home_ file server to store all photos & family
> videos, work related material, DNLA streaming and more.
>
> The server will be set to suspend when not in use for an hour or so.
>
> I've been thinking about buying 3 x 3 TB SATA disks and put these in
> software RAID5 (except for a smaller boot partition on all three disks
> which will be RAID1).
>
> Any recommendation for what SATA drives to get? Should I get
> enterprise drives that support TLER (or alike), or will the greener
> low cost drives be enough, is there something in between?
>
> Is it better to buy 4 low cost drives in RAID1 or 3 enterprise drives in
> RAID5?
>
> Please help, I'm completely lost!
>
> --john
> --
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>

-- 
Sent from my mobile device

Drew

"Nothing in life is to be feared. It is only to be understood."
--Marie Curie

"This started out as a hobby and spun horribly out of control."
-Unknown
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Re: Recommended sw raid setup

[Scott E. Armitage]

For your family photos/videos and work-related material, remember that
RAID is not a backup solution, and you should still use something like
an external hard-drive that you sync periodically and keep off-site,
like at work.

-S

On Sat, Jul 2, 2011 at 3:45 PM, Drew <drew.kay@gmail.com> wrote:
> Hi John,
>
> Personally I think you'd be fine with consumer grade drives. Put them
> in a RAID-5 array and you should be set.
>
> The high end consumer & enterprise stuff w/ TLER and the like is only
> really needed if you put a lot of demand on the disks, running virtual
> machines for example. A basic file server for home use won't stress
> the drives enough to need the more expensive ones.
>
>
> -Drew
>
> On 07/02/2011, John Obaterspok <john.obaterspok@gmail.com> wrote:
>> Hi,
>>
>> I've going to setup a _home_ file server to store all photos & family
>> videos, work related material, DNLA streaming and more.
>>
>> The server will be set to suspend when not in use for an hour or so.
>>
>> I've been thinking about buying 3 x 3 TB SATA disks and put these in
>> software RAID5 (except for a smaller boot partition on all three disks
>> which will be RAID1).
>>
>> Any recommendation for what SATA drives to get? Should I get
>> enterprise drives that support TLER (or alike), or will the greener
>> low cost drives be enough, is there something in between?
>>
>> Is it better to buy 4 low cost drives in RAID1 or 3 enterprise drives in
>> RAID5?
>>
>> Please help, I'm completely lost!
>>
>> --john
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>
>
> --
> Sent from my mobile device
>
> Drew
>
> "Nothing in life is to be feared. It is only to be understood."
> --Marie Curie
>
> "This started out as a hobby and spun horribly out of control."
> -Unknown
> --
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>



-- 
Scott Armitage, B.A.Sc., M.A.Sc. candidate
Space Flight Laboratory
University of Toronto Institute for Aerospace Studies
4925 Dufferin Street, Toronto, Ontario, Canada, M3H 5T6
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Re: Recommended sw raid setup

[Simon Matthews]

I thought that I had read the TLER was not useful for mdraid, so that
enterprise drives were not really advised for mdraid. Am I wrong about
this?

Also, for the original question: for a home system, do you really need
the uptime  that RAID provides? I suspect not -- in that case, put
your money into backups, not RAID.

Simon

On Sat, Jul 2, 2011 at 12:45 PM, Drew <drew.kay@gmail.com> wrote:
> Hi John,
>
> Personally I think you'd be fine with consumer grade drives. Put them
> in a RAID-5 array and you should be set.
>
> The high end consumer & enterprise stuff w/ TLER and the like is only
> really needed if you put a lot of demand on the disks, running virtual
> machines for example. A basic file server for home use won't stress
> the drives enough to need the more expensive ones.
>
>
> -Drew
>
> On 07/02/2011, John Obaterspok <john.obaterspok@gmail.com> wrote:
>> Hi,
>>
>> I've going to setup a _home_ file server to store all photos & family
>> videos, work related material, DNLA streaming and more.
>>
>> The server will be set to suspend when not in use for an hour or so.
>>
>> I've been thinking about buying 3 x 3 TB SATA disks and put these in
>> software RAID5 (except for a smaller boot partition on all three disks
>> which will be RAID1).
>>
>> Any recommendation for what SATA drives to get? Should I get
>> enterprise drives that support TLER (or alike), or will the greener
>> low cost drives be enough, is there something in between?
>>
>> Is it better to buy 4 low cost drives in RAID1 or 3 enterprise drives in
>> RAID5?
>>
>> Please help, I'm completely lost!
>>
>> --john
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>
>
> --
> Sent from my mobile device
>
> Drew
>
> "Nothing in life is to be feared. It is only to be understood."
> --Marie Curie
>
> "This started out as a hobby and spun horribly out of control."
> -Unknown
> --
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
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Re: Recommended sw raid setup

[Scott E. Armitage]

On Sat, Jul 2, 2011 at 5:17 PM, Simon Matthews
<simon.d.matthews@gmail.com> wrote:
> Also, for the original question: for a home system, do you really need
> the uptime  that RAID provides? I suspect not -- in that case, put
> your money into backups, not RAID.

If it suits your needs, I think a RAID setup is perfectly acceptable.
I have a RAID-5 array in my desktop computer at home. I have never had
a drive failure, though I have simulated it to practice replacing a
drive without loosing any data.

For myself, the reasoning was mostly to combine a bunch of drives into
one large logical volume, which greatly reduces workflow overhead.
That I can suffer a single drive failure and not have to resort to
restoring from a backup is simply a nice-to-have. I still backup my
important files to an external hard-drive on a semi-regular basis, but
there is much less mission-critical data (photos, documents) than
stuff that is simply annoying to lose (music and movies).

-S

-- 
Scott Armitage, B.A.Sc., M.A.Sc. candidate
Space Flight Laboratory
University of Toronto Institute for Aerospace Studies
4925 Dufferin Street, Toronto, Ontario, Canada, M3H 5T6
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Re: Recommended sw raid setup

[Drew]

> I thought that I had read the TLER was not useful for mdraid, so that
> enterprise drives were not really advised for mdraid. Am I wrong about
> this?

TLER just shortens the firmware's error recovery from something like
60 seconds down to 4 seconds. It's mainly useful in hardware RAID but
I can see it being useful with mdraid in the enterprise where you
can't afford to wait for the drive to do it's own recovery attempts.


-- 
Drew

"Nothing in life is to be feared. It is only to be understood."
--Marie Curie

"This started out as a hobby and spun horribly out of control."
-Unknown

Re: Recommended sw raid setup

[Emmanuel Noobadmin]

On 7/2/11, John Obaterspok <john.obaterspok@gmail.com> wrote:
> Any recommendation for what SATA drives to get? Should I get
> enterprise drives that support TLER (or alike), or will the greener
> low cost drives be enough, is there something in between?
>
> Is it better to buy 4 low cost drives in RAID1 or 3 enterprise drives in
> RAID5?

If you can afford either, I would personally recommend 4 low cost
drives in RAID 1. Since the drives are mirror, recovery is
straightforward and risk free. You could even put them in removable
enclosures and do backup simply by swapping out one drive of each
array.

Try to get drives from different manufacturers. You don't want to face
the kind of nightmares some of us had when/if there was a batch/model
problem, RAID can't help if all your drives brick or fail at the same
time due to the same problem.

Re: Recommended sw raid setup

[David Brown]

On 02/07/11 23:17, Simon Matthews wrote:
> I thought that I had read the TLER was not useful for mdraid, so that
> enterprise drives were not really advised for mdraid. Am I wrong about
> this?
>
> Also, for the original question: for a home system, do you really need
> the uptime  that RAID provides? I suspect not -- in that case, put
> your money into backups, not RAID.
>

If it's a choice of good backups /or/ raid, go for the backups every 
time.  But if you have the money and space for both, then do both.  Raid 
is not just about uptime - it is also about avoiding the effort and 
inconvenience of rebuilding or reinstalling.

mvh.,

David


> Simon
>
> On Sat, Jul 2, 2011 at 12:45 PM, Drew<drew.kay@gmail.com>  wrote:
>> Hi John,
>>
>> Personally I think you'd be fine with consumer grade drives. Put them
>> in a RAID-5 array and you should be set.
>>
>> The high end consumer&  enterprise stuff w/ TLER and the like is only
>> really needed if you put a lot of demand on the disks, running virtual
>> machines for example. A basic file server for home use won't stress
>> the drives enough to need the more expensive ones.
>>
>>
>> -Drew
>>
>> On 07/02/2011, John Obaterspok<john.obaterspok@gmail.com>  wrote:
>>> Hi,
>>>
>>> I've going to setup a _home_ file server to store all photos&  family
>>> videos, work related material, DNLA streaming and more.
>>>
>>> The server will be set to suspend when not in use for an hour or so.
>>>
>>> I've been thinking about buying 3 x 3 TB SATA disks and put these in
>>> software RAID5 (except for a smaller boot partition on all three disks
>>> which will be RAID1).
>>>
>>> Any recommendation for what SATA drives to get? Should I get
>>> enterprise drives that support TLER (or alike), or will the greener
>>> low cost drives be enough, is there something in between?
>>>
>>> Is it better to buy 4 low cost drives in RAID1 or 3 enterprise drives in
>>> RAID5?
>>>
>>> Please help, I'm completely lost!
>>>
>>> --john
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
>>> the body of a message to majordomo@vger.kernel.org
>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>>
>>
>> --
>> Sent from my mobile device
>>
>> Drew
>>
>> "Nothing in life is to be feared. It is only to be understood."
>> --Marie Curie
>>
>> "This started out as a hobby and spun horribly out of control."
>> -Unknown
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
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>

Re: Recommended sw raid setup

[John Obaterspok]

Hi all,

Thanks for all good answers!

Today I got all my family data spread in hux-flux between medicenter,
laptops, external disks - no redundancy what so ever.
I would really like to have a backup solution too, but how do I backup
6 TB in a fasion that makes me do it more than the first 5 times?

First I thought about using btrfs with snapshots on the RAID5 as a
substitute for backups, but that might not be worth it in the sense
that it doesn't give me much more safety?

--john

2011/7/3 David Brown <david.brown@hesbynett.no>:
> On 02/07/11 23:17, Simon Matthews wrote:
>>
>> I thought that I had read the TLER was not useful for mdraid, so that
>> enterprise drives were not really advised for mdraid. Am I wrong about
>> this?
>>
>> Also, for the original question: for a home system, do you really need
>> the uptime  that RAID provides? I suspect not -- in that case, put
>> your money into backups, not RAID.
>>
>
> If it's a choice of good backups /or/ raid, go for the backups every time.
>  But if you have the money and space for both, then do both.  Raid is not
> just about uptime - it is also about avoiding the effort and inconvenience
> of rebuilding or reinstalling.
>
> mvh.,
>
> David
>
>
>> Simon
>>
>> On Sat, Jul 2, 2011 at 12:45 PM, Drew<drew.kay@gmail.com>  wrote:
>>>
>>> Hi John,
>>>
>>> Personally I think you'd be fine with consumer grade drives. Put them
>>> in a RAID-5 array and you should be set.
>>>
>>> The high end consumer&  enterprise stuff w/ TLER and the like is only
>>> really needed if you put a lot of demand on the disks, running virtual
>>> machines for example. A basic file server for home use won't stress
>>> the drives enough to need the more expensive ones.
>>>
>>>
>>> -Drew
>>>
>>> On 07/02/2011, John Obaterspok<john.obaterspok@gmail.com>  wrote:
>>>>
>>>> Hi,
>>>>
>>>> I've going to setup a _home_ file server to store all photos&  family
>>>> videos, work related material, DNLA streaming and more.
>>>>
>>>> The server will be set to suspend when not in use for an hour or so.
>>>>
>>>> I've been thinking about buying 3 x 3 TB SATA disks and put these in
>>>> software RAID5 (except for a smaller boot partition on all three disks
>>>> which will be RAID1).
>>>>
>>>> Any recommendation for what SATA drives to get? Should I get
>>>> enterprise drives that support TLER (or alike), or will the greener
>>>> low cost drives be enough, is there something in between?
>>>>
>>>> Is it better to buy 4 low cost drives in RAID1 or 3 enterprise drives in
>>>> RAID5?
>>>>
>>>> Please help, I'm completely lost!
>>>>
>>>> --john
>>>> --
>>>> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
>>>> the body of a message to majordomo@vger.kernel.org
>>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>>>
>>>
>>> --
>>> Sent from my mobile device
>>>
>>> Drew
>>>
>>> "Nothing in life is to be feared. It is only to be understood."
>>> --Marie Curie
>>>
>>> "This started out as a hobby and spun horribly out of control."
>>> -Unknown
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
>>> the body of a message to majordomo@vger.kernel.org
>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>>
>> --
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>> the body of a message to majordomo@vger.kernel.org
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>>
>
>
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Re: Recommended sw raid setup

[David Brown]

On 03/07/11 21:14, John Obaterspok wrote:
> Hi all,
>
> Thanks for all good answers!
>
> Today I got all my family data spread in hux-flux between medicenter,
> laptops, external disks - no redundancy what so ever.
> I would really like to have a backup solution too, but how do I backup
> 6 TB in a fasion that makes me do it more than the first 5 times?
>
> First I thought about using btrfs with snapshots on the RAID5 as a
> substitute for backups, but that might not be worth it in the sense
> that it doesn't give me much more safety?
>

It's vital that backups are to a different machine or offline disks (for 
protection from software or hardware problems, or user problems), and 
preferably stored in a different place if that's practical (for 
protection from fire and theft).

You can do a lot with a single 2 or 3 TB external disk.  If you find 
you're needing several disks, it's cheaper to get a hot-swap external 
disk holder and a few bare drives (go for a eSATA connection if you can).

For transferring data, use rsync - it will only copy the changes.  If 
you want snapshots of your data, rsync can do that too (or you can use 
rsnapshot or dirvish to automate this if you don't want to learn the 
rsync command line switches).

The ideal arrangement, at least in countries with fast internet access, 
is to have a backup server in a different place and rsync over the internet.

Re: Recommended sw raid setup

[Stefan /*St0fF*/ Hübner]

Am 02.07.2011 23:30, schrieb Drew:
>> I thought that I had read the TLER was not useful for mdraid, so that
>> enterprise drives were not really advised for mdraid. Am I wrong about
>> this?
> 
> TLER just shortens the firmware's error recovery from something like
> 60 seconds down to 4 seconds. It's mainly useful in hardware RAID but
> I can see it being useful with mdraid in the enterprise where you
> can't afford to wait for the drive to do it's own recovery attempts.
> 
> 
This is not correct.  You may want to read the ATA8-ACS2 draft standard
(see www.t13.org).  There you'll find: SCT-ERC

The internal error recovery procedure includes a vast amount of
algorithms.  If a disk cannot read a sector and starts error recovery,
it may take far more than a minute.
With ERC you can tell the disk beforehand to stop processing the command
(may it be "read" or "write") and return a "uncorrectable error" to the
host.  Some drives (i.E. recent Hitachi Deskstar, which I do recommend!)
do not allow you to set ERC lower than 6.5s.

For a home-box I recommend adding a startup-script and a hotplug-script
(as ERC-settings get reset to firmware defaults upon power-on) which
uses smartmontools >=5.41 to set the read-ERC to 7s and the write ERC to
12s.  We have good experience that this works out well in productive
systems.

/Stefan
P.S.: pseudo-knowledge makes important things go really badly wrong.

Re: Recommended sw raid setup

[Drew]

>> TLER just shortens the firmware's error recovery from something like
>> 60 seconds down to 4 seconds. It's mainly useful in hardware RAID but
>> I can see it being useful with mdraid in the enterprise where you
>> can't afford to wait for the drive to do it's own recovery attempts.
>>
>>
> This is not correct.  You may want to read the ATA8-ACS2 draft standard
> (see www.t13.org).  There you'll find: SCT-ERC
>
> The internal error recovery procedure includes a vast amount of
> algorithms.  If a disk cannot read a sector and starts error recovery,
> it may take far more than a minute.
> With ERC you can tell the disk beforehand to stop processing the command
> (may it be "read" or "write") and return a "uncorrectable error" to the
> host.  Some drives (i.E. recent Hitachi Deskstar, which I do recommend!)
> do not allow you to set ERC lower than 6.5s.

And how is that any different from what I said? The observable effect
of TLER is the drive giving up after a few seconds instead of a minute
or more. Algorithm XYZ and spec ABC of the t13 committee doesn't
change what we see. And for most people, the effect is what matters,
not how we got there.

Myself, I could care less about what goes on under the hood. I enable
TLER for HW raid and disable it for regular use.


-- 
Drew

"Nothing in life is to be feared. It is only to be understood."
--Marie Curie

"This started out as a hobby and spun horribly out of control."
-Unknown
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