Compaq Smart Array 3200 Controller as a SCSI Controller
lproven at gmail.com
Thu Jul 16 06:36:04 CDT 2020
On Wed, 15 Jul 2020 at 22:09, Ali via cctalk <cctalk at classiccmp.org> wrote:
> > There is no good use case for them in 2020, which is why they're all
> > suddenly
> > quite cheap.
> Why do you say that? Not disagreeing per se but just wondering the reasoning
> behind it.
Happily for me I don't do stuff like build production servers any
more, but my understanding is this:
With modern hardware, it's easier, cheaper and more flexible to build
and manage arrays in software, using modern filesystems such as ZFS,
Btrfs, or MS Storage Spaces on Windows Server.
I was recently documenting the use of Btrfs for this on SUSE Linux
Enterprise Server: the benefits of doing it in software are that you
can dynamically migrate arrays between different RAID levels, add new
drives and resize the array to include them or add them as additional
parity disks on the fly, you can mark individual files as having
different RAID levels (for example, you could place the OS' virtual
memory space in a file on the RAID and tell the filesystem not to
compute parity for it, just stripe it, for better performance). ZFS
and Ceph allow for a mix of high-speed (e.g. SSD, NVMe, even NVDIMM)
storage and low-speed but large rotational storage, and use the faster
storage to cache the slower stuff.
And of course, if your server dies, then the array can be mounted on
any other box with the same OS and you can retrieve data from it --
which is far more difficult if a hardware RAID controller dies, in
which case you might need the same firmware revision etc., and
possibly onboard controller config info.
Ceph now basically lets you build arrays of storage servers, so that
you can, say, have single storage volumes comprising local storage in
different countries, or on different continents, for local access
speed and the software syncs it in the background between zones or
regions. So it's no longer an array of physical disks on one server,
it's an array of servers with disks in them -- and the servers and the
disks may themselves be virtualised.
It gets very complicated but it's also very powerful and flexible.
Dedicated hardware just can't do stuff like this any more.
Liam Proven – Profile: https://about.me/liamproven
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