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ceph Archives - AWS Managed Services by Anchor

Rebuilding An OpenStack Instance and Keeping the Same Fixed IP

By | General | No Comments

OpenStack and in particular the compute service, Nova, has a useful rebuild function that allows you to rebuild an instance from a fresh image while maintaining the same fixed and floating IP addresses, amongst other metadata. However if you have a shared storage back end, such as Ceph, you’re out of luck as this function is not for you. Fortunately, there is another way. Prepare for the Rebuild: Note the fixed IP address of the instance that you wish to rebuild and the network ID: $ nova show demoinstance0 | grep network | DemoTutorial network | 192.168.24.14, 216.58.220.133 | $ export FIXED_IP=192.168.24.14 $ neutron floatingip-list | grep 216.58.220.133 | ee7ecd21-bd93-4f89-a220-b00b04ef6753 | | 216.58.220.133 | $ export FLOATIP_ID=ee7ecd21-bd93-4f89-a220-b00b04ef6753 $ neutron net-show DemoTutorial | grep ” id ” | id | 9068dff2-9f7e-4a72-9607-0e1421a78d0d…

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A Year of OpenStack

By | General | One Comment

In late 2013 we looked around the company and asked ourselves the questions any management team has to ask: what are we doing, where do we need to be, and what’s holding us back from getting there? Because Anchor had grown organically across many years, our internal procedures for infrastructure management were spread across a number of tools that weren’t scalable and efficient enough to keep up with the demands of new sales. Furthermore, they weren’t compatible with a product-based self-serve future. There are a number of pieces to addressing that, but certainly it would be tremendously useful to have API-driven software defined infrastructure. The recommendation, universally, was that we needed to consider OpenStack. We were astonished at the degree of rigour and testing that had gone into vetting changes (since the beginning, there have been no un-gated…

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Pulling apart Ceph’s CRUSH algorithm

By | Technical | One Comment

As you’ve probably noticed, we’ve been evaluating Ceph in recent months for our petabyte-scale distributed storage needs. It’s a pretty great solution and works well, but it’s not the easiest thing to setup and administer properly. One of the bits we’ve been grappling with recently is Ceph’s CRUSH map. In certain circumstances, which aren’t entirely clearly documented, it can fail to do the job and lead to a lack of guaranteed redundancy. How CRUSH maps work The CRUSH map algorithm is one of the jewels in Ceph’s crown, and provides a mostly deterministic way for clients to locate and distribute data on disks across the cluster. This avoids the need for an index server to coordinate reads and writes. Clusters with index servers, such as the MDS in Lustre, funnel…

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The dust settles on Anchor’s first Hackfest

By | Technical | No Comments

We’re currently in the process of beta-testing RADOS Gateway with a view to producing a viable product, it’s an S3-compatible cloud storage solution. We’ve done a good amount of smoketesting and turned up our fair share of buggy behaviour, but what it really needs is a good shakedown. Thus, Anchor’s first hackfest was held last Friday to show off what can be done with our deployment of RADOS Gateway, named Trove, and see if it really shines. We wanted to keep things fairly low key for a first-attempt hackfest, so we only invited a small number of staff and their geeky friends, and put together several programming teams. Hackfests are generally pretty freeform and light on restrictions, which is how we ran it. The rules: Build anything you want, though…

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Bughunting in Ceph’s radosgw: ETags

By | Technical | No Comments

RADOS Gateway (henceforth referred to as radosgw) is an add-on component for Ceph, large-scale clustered storage now mainlined in the Linux kernel. radosgw provides an S3-compatible interface for object storage, which we’re evaluating for a future product offering. We’ve spent the last few days digging through radosgw source trying to nail a some pesky bugs. For once, the clients don’t appear to be breaking spec, it’s radosgw itself. We’re using DragonDisk as our S3-alike client – what works? PUTing and GETing files works, obviously. Setting the Content-Type metadata returns a failure, and renaming a directory almost works – it gets duplicated to the new name, but the old copy hangs around. Wireshark to the rescue! We started pulling apart packet dumps, and it quickly became evident that setting Content-Type on…

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A crash course in Ceph, a distributed replicated clustered filesystem

By | Technical | 3 Comments

We’ve been looking at Ceph recently, it’s basically a fault-tolerant distributed clustered filesystem. If it works, that’s like a nirvana for shared storage: you have many servers, each one pitches in a few disks, and the there’s a filesystem that sits on top that visible to all servers in the cluster. If a disk fails, that’s okay too. Those are really cool features, but it turns out that Ceph is really more than just that. To borrow a phrase, Ceph is like an onion – it’s got layers. The filesystem on top is nifty, but the coolest bits are below the surface. If Ceph proves to be solid enough for use, we’ll need to train our sysadmins all about Ceph. That means pretty diagrams and explanations, which we thought would…

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