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recommendations for supported, affordable hardware raid controller.

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  recommendations for supported, affordable hardware raid controller. Steven Mainor <steve@degga.net> - 2021-01-01 19:10 +0100
    Re: recommendations for supported, affordable hardware raid  controller. "Alexander V. Makartsev" <avbetev@gmail.com> - 2021-01-01 20:00 +0100
    Re: recommendations for supported, affordable hardware raid  controller. Dan Ritter <dsr@randomstring.org> - 2021-01-01 20:00 +0100
      Re: recommendations for supported, affordable hardware raid controller. Sven Hartge <sven@svenhartge.de> - 2021-01-01 20:40 +0100
    Re: recommendations for supported, affordable hardware raid  controller. David Christensen <dpchrist@holgerdanske.com> - 2021-01-01 21:10 +0100
      Re: recommendations for supported, affordable hardware raid  controller. Steven Mainor <steve@degga.net> - 2021-01-02 09:30 +0100
        Re: recommendations for supported, affordable hardware raid  controller. Steven Mainor <steve@degga.net> - 2021-01-02 09:50 +0100
    Re: recommendations for supported, affordable hardware raid  controller. Michael Stone <mstone@debian.org> - 2021-01-01 21:20 +0100
    Re: recommendations for supported, affordable hardware raid  controller. Steven Mainor <steve@degga.net> - 2021-01-02 09:20 +0100
      Re: recommendations for supported, affordable hardware raid  controller. David Christensen <dpchrist@holgerdanske.com> - 2021-01-02 10:50 +0100
        Re: recommendations for supported, affordable hardware raid  controller. Andrei POPESCU <andreimpopescu@gmail.com> - 2021-01-02 12:30 +0100
          Re: recommendations for supported, affordable hardware raid  controller. Richard Hector <richard@walnut.gen.nz> - 2021-01-02 17:10 +0100
            Re: recommendations for supported, affordable hardware raid controller. Gene Heskett <gheskett@shentel.net> - 2021-01-02 17:50 +0100
          Re: recommendations for supported, affordable hardware raid  controller. David Christensen <dpchrist@holgerdanske.com> - 2021-01-02 22:40 +0100
            Re: recommendations for supported, affordable hardware raid  controller. Andrei POPESCU <andreimpopescu@gmail.com> - 2021-01-03 10:30 +0100
              Re: recommendations for supported, affordable hardware raid  controller. David Christensen <dpchrist@holgerdanske.com> - 2021-01-03 22:50 +0100
                Re: recommendations for supported, affordable hardware raid  controller. Andrei POPESCU <andreimpopescu@gmail.com> - 2021-01-04 08:30 +0100
              Re: recommendations for supported, affordable hardware raid controller. Stefan Monnier <monnier@iro.umontreal.ca> - 2021-01-03 23:20 +0100
              Re: recommendations for supported, affordable hardware raid  controller. Michael Stone <mstone@debian.org> - 2021-01-04 02:00 +0100
                Re: recommendations for supported, affordable hardware raid  controller. Andrei POPESCU <andreimpopescu@gmail.com> - 2021-01-04 08:40 +0100
                  Re: recommendations for supported, affordable hardware raid  controller. Michael Stone <mstone@debian.org> - 2021-01-04 14:40 +0100
      Re: recommendations for supported, affordable hardware raid controller. Sven Hartge <sven@svenhartge.de> - 2021-01-02 12:50 +0100
        Re: recommendations for supported, affordable hardware raid controller. Nicholas Geovanis <nickgeovanis@gmail.com> - 2021-01-02 16:30 +0100
          Re: recommendations for supported, affordable hardware raid controller. Sven Hartge <sven@svenhartge.de> - 2021-01-02 17:30 +0100
          Re: recommendations for supported, affordable hardware raid  controller. Alain D D Williams <addw@phcomp.co.uk> - 2021-01-02 18:40 +0100
    Re: recommendations for supported, affordable hardware raid controller. deloptes <deloptes@gmail.com> - 2021-01-02 10:00 +0100

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#230325 — Re: recommendations for supported, affordable hardware raid controller.

On Mon, Jan 04, 2021 at 09:30:08AM +0200, Andrei POPESCU wrote:
>On Du, 03 ian 21, 19:53:07, Michael Stone wrote:
>> Applications which need more data integrity
>> guarantees generally implement some sort of journalling and/or use atomic
>> filesystem operations. (E.g., write a temporary file, flush/sync,
>> rename--that guarantees either the old file or the new file will be present,
>> but not a partially written file.)
>
>Unless I'm mistaken, this is somewhat similar to how copy-on-write works
>for every write, except that the copy-on-write is done at block level
>and with the added benefits that unchanged blocks are kept as they are
>(less writes) and may even be shared between files (using less space).

COW is a different, somewhat related, thing. In itself it isn't 
sufficient for an application to be assured about the on-disk state at a 
particular time without using additional filesystem operations beyond a 
simple write(). In practice, those operations are a subset of what's 
necessary for other filesystems and most applications concerned about 
data integrity are going to implement the full set. (Few people want 
filesystem-specific applications.)

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#230241

Steven Mainor <steve@degga.net> wrote:

> The idea was to create a large striped raid array(perhaps RAID6) of 
> spinning disks to use as a large storage area for extra VM backups and 
> large projects I'm working on. And in the process I could learn more 
> about RAID controllers.

To be honest: RAID controllers are on their way out, a thing of the
past.

Performance-wise, MD-RAID or ZFS on Linux is faster than doing the same
via a RAID controller, while at the same time having far less
complexity and failure points.

RAID controllers need a prioprietary tool to configure and maintain
them, hide your disks behind a single block device and then often make
it difficult or impossible to check them, for example via smartd.

You have to rely on the proprietary tool to notify you of a disk failure
and hope it works and keeps working. I have quite often seen these tools
only be availble for ancient Red Hat versions and a pain to get to work
on anything else.

My advise: Don't bother "learning RAID controllers".

Grüße,
Sven.

-- 
Sigmentation fault. Core dumped.

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#230255

[Multipart message — attachments visible in raw view] — view raw

On Sat, Jan 2, 2021, 5:49 AM Sven Hartge <sven@svenhartge.de> wrote:

>
> My advise: Don't bother "learning RAID controllers".
>

Im afraid I have to agree with this advice. In the presence of software
like ZFS (from Sun) and LVM (from IBM's AIX), with easy availability of
NAS, SAN and cloud storage, the arguments in favor of hardware RAID local
to a server become much thinner. What drives that change is the evolution
of hardware and networking, not so much the software. Both ZFS and LVM are
now 20 years old, very mature software.

Grüße,
> Sven.
>
> --
> Sigmentation fault. Core dumped.
>
>

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#230262

Nicholas Geovanis <nickgeovanis@gmail.com> wrote:
> On Sat, Jan 2, 2021, 5:49 AM Sven Hartge <sven@svenhartge.de> wrote:

>> My advise: Don't bother "learning RAID controllers".

> Im afraid I have to agree with this advice. In the presence of
> software like ZFS (from Sun) and LVM (from IBM's AIX), with easy
> availability of NAS, SAN and cloud storage, the arguments in favor of
> hardware RAID local to a server become much thinner. What drives that
> change is the evolution of hardware and networking, not so much the
> software. Both ZFS and LVM are now 20 years old, very mature software.

I see in my environment real RAID controllers only for special systems:

1) standalone ESX servers
2) standalone Windows servers

For ESX servers, as soon as there are 2 or more, they usually are part
of a VSAN (which wants direct access to the disks) or connected to a
proper SAN (mainly NetApp) and boot off of a pair of SD cards or a
BOSS-card containing 2 NVMe modules. (While the latter is kind-of a
RAID controller, it is as simple as they get.)

For Windows servers, the water gets a bit muddles by the existance of
"Storage Spaces", which is more like LVM an Linux, allowing for a
RAID-like usage for every volume created therein.

In that case, the Windows server also gets a very simple RAID controller
or a BOSS card to boot from.

And that is mostly it. Everything else uses MD-RAID and ZFS or uses
object storage provided by (for example) MinIO.

RAID controllers served a purpose when the CPUs were slow, the bandwidth
between the memory, the CPU and the storage was bottlenecked and you
needed a special RAID CPU to offload the needed calculations.

But today: No such thing anymore.

My personal measurements using an LSI card in IR and in IT mode also
confirm this: Using IT mode which just passes the disks through to the
system and using ZFS in RAIDZ2 mode was leaps and bounds faster than the
RAID6 mode native to the controller.

Then add in the faster resilver in case of failure, the ability to
checksum every block and guarantee the correctness of the data and ZFS
wins by a large stretch.

Grüße,
Sven.

-- 
Sigmentation fault. Core dumped.

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#230265 — Re: recommendations for supported, affordable hardware raid controller.

On Sat, Jan 02, 2021 at 09:23:02AM -0600, Nicholas Geovanis wrote:

> Im afraid I have to agree with this advice. In the presence of software
> like ZFS (from Sun) and LVM (from IBM's AIX), with easy availability of
> NAS, SAN and cloud storage, the arguments in favor of hardware RAID local
> to a server become much thinner. What drives that change is the evolution
> of hardware and networking, not so much the software. Both ZFS and LVM are
> now 20 years old, very mature software.

If you have H/W raid and the controller breaks (it will do if you use it long
enough) then you need to replace it by the same/similar controller. A few years
down the line this might be hard and may take some time.

When you use S/W raid then you do not have this problem. Replace the broken
controller or move the disks to a new machine, do a bit of config and you are
back in action.

You sound like an individual: the compatible H/W controller might be a problem.

If you were a business then keeping a few replacement controllers is affordable
so the balance is different.

My 2 pence.

-- 
Alain Williams
Linux/GNU Consultant - Mail systems, Web sites, Networking, Programmer, IT Lecturer.
+44 (0) 787 668 0256  https://www.phcomp.co.uk/
Parliament Hill Computers Ltd. Registration Information: https://www.phcomp.co.uk/Contact.html
#include <std_disclaimer.h>

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#230224

Steven Mainor wrote:

> I'm looking for recommendations for a 6 or 8 port SATA hardware raid
> controller that will hopefully be supported by the kernel and/or open
> source drivers to put in my desktop computer. Any input welcome, thanks.
> 

I recommend installing two controllers and planning your drives such that if
one controller fails the other may take over without loosing any drive
redundancy.

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