We run a ~1PByte HBase cluster on top of Hadoop/HDFS that works pretty
well. I would love to be able to use Cassandra instead on a system
like that. HBase queries / scans are not the easiest to deal with,
but, as with Cassandra, if you know the primary key, you can get to your
data fast, even in trillions of rows. Cassandra offers some
capabilities that HBase doesn't that I would like to leverage, but yeah
- how can you use Cassandra with modern equipment in a bare metal
environment? Kubernetes could make sense as long as you're able to
maintain data locality with however your storage is configured.
Even all SSDs - you can get a system with 24, 2 TByte SSDs, which is too
large for 1 instance of Cassandra. Does 4.x address any of this?
Ebay uses Cassandra and claims to have 80+ petabytes. What do they do?
-Joe
On 4/8/2021 6:35 PM, Elliott Sims wrote:
I'm not sure I'd suggest building a single DIY Backblaze pod. The
SATA port multipliers are a pain both from a supply chain and systems
management perspective. Can be worth it when you're amortizing that
across a lot of servers and can exert some leverage over wholesale
suppliers, but less so for a one-off. There's a lot more
whitebox/OEM/etc options for high-density storage servers these days
from Seagate, Dell, HP, Supermicro, etc that are worth a look.
I'd agree with this (both examples) sounding like a poor fit for
Cassandra. Seems like you could always just spin up a bunch of
Cassandra VMs in the ESX cluster instead of one big one, but something
like MySQL or PostgreSQL might suit your needs better. Or even some
sort of flatfile archive with something like Parquet if it's more
being kept "just in case" with no need for quick random access.Â
For the 10PB example, it may be time to look at something like Hadoop,
or maybe Ceph.
On Thu, Apr 8, 2021 at 10:39 AM Bowen Song <bo...@bso.ng> wrote:
This is off-topic. But if your goal is to maximise storage density
and also ensuring data durability and availability, this is what
you should be looking at:
* hardware:
https://www.backblaze.com/blog/open-source-data-storage-server/
<https://www.backblaze.com/blog/open-source-data-storage-server/>
* architecture and software:
https://www.backblaze.com/blog/vault-cloud-storage-architecture/
<https://www.backblaze.com/blog/vault-cloud-storage-architecture/>
On 08/04/2021 17:50, Joe Obernberger wrote:
I am also curious on this question.� Say your use case is to
store 10PBytes of data in a new server room / data-center with
new equipment, what makes the most sense? If your database is
primarily write with little read, I think you'd want to maximize
disk space per rack space. So you may opt for a 2u server with
24 3.5" disks at 16TBytes each for a node with 384TBytes of disk
- so ~27 servers for 10PBytes.
Cassandra doesn't seem to be the good choice for that
configuration; the rule of thumb that I'm hearing is ~2Tbytes per
node, in which case we'd need over 5000 servers. This seems
really unreasonable.
-Joe
On 4/8/2021 9:56 AM, Lapo Luchini wrote:
Hi, one project I wrote is using Cassandra to back the huge
amount of data it needs (data is written only once and read very
rarely, but needs to be accessible for years, so the storage
needs become huge in time and I chose Cassandra mainly for its
horizontal scalability regarding disk size) and a client of mine
needs to install that on his hosts.
Problem is, while I usually use a cluster of 6 "smallish" nodes
(which can grow in time), he only has big ESX servers with huge
disk space (which is already RAID-6 redundant) but wouldn't have
the possibility to have 3+ nodes per DC.
This is out of my usual experience with Cassandra and, as far as
I read around, out of most use-cases found on the website or
this mailing list, so the question is:
does it make sense to use Cassandra with a big (let's talk 6TB
today, up to 20TB in a few years) single-node DataCenter, and
another single-node DataCenter (to act as disaster recovery)?
Thanks in advance for any suggestion or comment!
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