Storage on The IT Hollow

Microsoft's Resilient File System (ReFS)

Mon, 13 Jan 2014 14:30:52 +0000

Microsoft has a new file system designed to increase data integrity, scalability and availability called the Resilient File System (ReFS). This file system has leveraged many of the NTFS file system goodies and expanded them to make it more scalable and prevent corruptions. ReFS was released with Server 2012 and at the moment is designed for use with file shares. It cannot be used as a boot volume at the present time, but this file system seems poised to replace NTFS down the road.

Microsoft Storage Spaces

Mon, 06 Jan 2014 14:15:25 +0000

Microsoft Storage Spaces feature used to handle data redundancy, scalability and performance. Storage Spaces takes a set of Just a Bunch of Disks (JBOD) and pairs them together to allow for; either failures of a disk, gaining the performance of multiple spindles, or gaining the space of multiple disks. Traditionally this has all been handled by creating a Redundant Array of Independent Disks (RAID) group. Some examples of RAID would be:

Striping (RAID 0)
Mirroring (RAID 1)
Parity (RAID 5 or 6)

Storage Spaces create a similar type of RAID Group but then throw a virtual disk on top of them so that multiple types of stripes can be used on the same disks. For example, three physical disks can be put into a storage space. From there, three separate types of VDISKs can be created, Mirrored, Spanned and Parity can then be placed on the same set of disks with no issue. The diagram below shows an example.

CASL with Nimble Storage

Mon, 25 Nov 2013 13:30:54 +0000

I was fortunate enough to get to spend an hour with Dmitriy Sandler from Nimble Storage to see what all the fuss was about with their product and more specifically their Cache Accelerated Sequential Layout (CASL) File System.

Hardware Overview

Let’s cover some of the basics before we dive into CASL. The storage array comes fully loaded with all the bells and whistles, out of the box. All the software features are included with this iSCSI array and include items such as:

Disk Latency Concepts

Mon, 18 Nov 2013 14:00:41 +0000

Hard drives are not the most fun thing to talk about, but it’s important to know some of the concepts when it comes to disk latency. Disk latency refers to the time delay between a request for data and the return of the data. It sounds like a simple thing, but this time can be critical to the performance of a system.

We should be surprised that traditional hard disks work at all when we consider that head designed to read minute magnetic fields sits 3 nanometers off a platter is spinning between 5400RPM and 15,000 RPM. Amazing when you stop to think about it huh?

Understanding the SSD write performance cliff

Mon, 28 Oct 2013 13:00:59 +0000

Solid State drives are much faster than their spinning disk predecessors, but can also have performance degradation due to how they interact with Operating Systems.

Flash consists of blocks of data and those blocks are full of smaller items called pages. A typical SSD might have block sizes of 512KB and 4KB pages.

There are 3 statuses that a healthy page could be in on a flash disk.

Written to: Data from the OS has been written to the page.
Unwritten to: The page is free and available to be written to by the Operation System.
Invalid: The page has data in it, but is available to be overwritten by the Operating System.

Windows Server 2012 as a Storage Device for vSphere Home Lab

Tue, 24 Sep 2013 13:30:39 +0000

If you’ve got a some hardware lying around for your lab, Windows Server 2012 may be a great solution for a home storage device. You can now do both block (iSCSI) and NAS (NFS) on the same server, as well as having an OS to install some management apps on it. In my lab, I use this management server to run Veeam for my backups, PRTG network monitor for bandwidth tracking, as well as using this server for both iSCSI targets and NFS mounts.

HP StoreOnce VSA

Tue, 16 Jul 2013 14:08:08 +0000

HP announced a new virtual storage appliance (VSA) recently at their annual HP Discover conference. This is a virtual appliance based on the StoreOnce line (formerly known as D2D) of hardware appliances that HP has sold for a long time. These appliances have the catalyst software which allows for deduplication of all your backup data, hence the term StoreOnce.

These devices have allowed administrators to switch from the older tape based backups to a virtual tape library (VTL) or a NAS type backup solution. It has replication options in it which allow for deduplicated data to be migrated or copied without re-hydrating the backups and wasting valuable bandwidth. It also allows for federated backups and when matched with HP Data Protector 8 (also newly released) can throttle bandwidth during backup operations in order to prevent production slow downs.

Synology DS411slim Review

Mon, 01 Jul 2013 13:57:10 +0000

I recently purchased a Synology DS411slim NAS device for my home lab in order to quiet down my rack and start using up less power. Obviously to accomplish this I would need to fill it up with Solid State drives which have the added benefit of a large number of IOPS :)

I screwed my four 480GB OCZ SSD’s into the drive cages and slipped them into the chassis. Really my only con for this device was getting the drives into the chassis. I did have to do a bit of wiggling to get them seated correctly.

Are you thin or thick? Where at?

Tue, 26 Mar 2013 13:47:47 +0000

I’m often asked about how to provision virtual machine disks. This almost always comes down to, “Should I use thick or thin disks?” and then “Should I do thin provisioning on the array or on the hypervisor?”

So here we go: Thin vs Thick

Thin provisioning:

Thin provisioned disks don’t allocate all of the space during the provisioning of the storage. Instead, they allocate the space on demand. This is a great way to get more bang for you buck out of your storage. Let’s take a closer look with an example.

Virtual Simulators

Tue, 19 Feb 2013 14:02:16 +0000

If you’re an engineer and you’re trying to get more experience with a variety of different storage devices, you might find yourself in a bit of a pickle. Most customers settle one one or two storage vendors and that’s it. So if you work for one of these companies you can learn EMC or Netapp, etc. I highly doubt your company would be interested in purchases a few different types of storage devices so that you can learn them as they are quite expensive.

VMware Path Masking

Tue, 30 Oct 2012 13:15:34 +0000

I’ve written posts in the past regarding LUN masking on a storage array, but it is possible to mask a path directly from your vSphere environment. I feel that if at all possible the masking should be handled at array level because the array is closest to the disk. Let’s face it, if vSphere shouldn’t see a LUN for one reason or another, then why is the array presenting it in the first place?

Network RAID Penalty

Mon, 17 Sep 2012 01:42:23 +0000

I recently got my hands on a pair of HP P4300s in the lab and wanted to see how the performance was with Network RAID. One of the most read posts on this site is on Understanding RAID Penalty and I was curious to see how Network RAID played into this equation.

Basic Setup

I have 2 HP P4300s, each with eight 15k SAS drives in a RAID 5 configuration. This means that I should have a total of 1400 RAW IOPS (8 disks * 175 IOPS) on each lefthand node. Since I have 2 of them, I’m calculating 2800 RAW IOPS. In order to get some real world functional IOPS, we’ll assume that we have 50% Reads and 50% Writes, and don’t forget to take out the RAID Penalty for the RAID 5. Let’s plug this into our Functional IOPS equation to get:

HP Storage Comparisons (Sept. 2012)

Mon, 10 Sep 2012 12:00:26 +0000

I have been recently thrown into the world of HP Storage, and have been trying to learn all of the storage techniques that are in the HP product line. I noticed that I couldn’t find anything that really did a compare and contrast of each of the products so I started to put one together. Anything I couldn’t understand, I asked a great guy named Calvin Zito (@hpstorageguy) to give me a hand with. He was more than gracious so follow him on Twitter.

Netapp AggrSpaceCheck 2.0 needed

Sun, 01 Jul 2012 22:34:57 +0000

I was recently helping out a company attempt to upgrade their Netapp Filer from OnTap 7.3 over to Data OnTap 8. We ran the Netapp Upgrade advisor and got to a section that wanted us to run the AggrSpaceCheck tool to make sure that the aggregates had sufficient space available. Normally, I skip this step because I usually have plenty of space available, but in this particular case, some of the aggregates were already 99% full. Since we didn’t want to have a serious failure during our upgrade we decided to error on the side of caution (and best practices) and run the AggrSpaceCheck tool.

Netapp VASA Provider 1.0

Tue, 01 May 2012 18:58:25 +0000

Netapp has released their vStorage APIs for Storage Awareness (VASA) provider 1.0 to their support site. http://support.netapp.com If you’re not that familiar with the VASA concept, this article should explain what it is and how it’s used in regards to VMware vSphere 5.

What is VASA?

VASA Providers collect information about your storage systems and present that information to vSphere. In previous versions of vSphere, an administrator might need to keep track of hisher datastores in a spreadsheet or have a naming convention that showed the properties of an individual datastore. For example, if your storage system had both SSD and Sata disks, the Datastore might be named VMFS01_SSD or something similar.

SQL HA Mirroring with vCenter

Sun, 15 Apr 2012 21:27:51 +0000

We’re probably all aware of the benefits of clustering things like SQL Server in order to provide highly available data. But shared storage clustering has some drawbacks on VMware ESXi clusters such as not being able to vMotion.

• Database Mirroring – SQL Server database mirrors utilize a non-shared storage availability solution, using built-in SQL Server replication technology to create and maintain one or more copies of each database on other SQL Servers in the environment. SQL Server database mirrors provide application-aware availability, and the lack of a quorum disk makes this a VMware-friendly solution, allowing the full use of vMotion, DRS, and HA.

Netapp VSC4 Optimization and Migration

Tue, 10 Apr 2012 23:40:13 +0000

One of my most frequently read articles is on how to use MBRAlign to align your virtual machine disks on Netapp storage. Well, after Netapp has released their new Virtual Storage Console (VSC4) the tedious task of using MBRAlign might be eased for some admins.

Optimization and Migration The new VSC4 console for vSphere has a new tab called Optimization and Migration. Here you are able to scan all or some of your datastores to check the alignment of your virtual machines. The scan manager can even be set on a schedule so that changes to the datastore will be recognized.

Understanding RAID Penalty

Wed, 21 Mar 2012 15:34:22 +0000

Determining which type of RAID to use when building a storage solution will largely depend on two things; capacity and performance. Performance is the topic of this post.

We measure disk performance in IOPS or Input/Output per second. One read request or one write request = 1 IO. Each disk in you storage system can provide a certain amount of IO based off of the rotational speed, average latency and average seek time. I’ve listed some averages for each type of disk below.

Lun Masking vs Zoning

Tue, 13 Mar 2012 01:27:47 +0000

Zoning and Lun Masking are often confused for each other, probably because both of them are used to restrict access to storage. They should both be used to secure the storage network and reduce unnecessary traffic.

Zoning

If you want to specify only certain hosts from accessing a storage device then you would want to setup zoning. For instance, in the example below, you can see that the two servers on the right can access three of the four storage devices, whereas the two on the left can only access two of the SANs. This configuration is done on the Fibre Channel switch. iSCSI, NFS, and FCoE can also be segmented, but they would use typical TCPIP segmentation methods like setting up a VLAN.

Path Selection Policy with ALUA

Thu, 08 Mar 2012 13:58:05 +0000

It’s important to understand how VMware ESXi servers handle connections to their associated storage arrays.

If we look specifically with fibre channel fabrics, we have several multipathing options to be considered. There are three path selection policy (PSP) plugins that VMware uses natively to determine the I/O channel that data will travel over to the storage device.

Fixed Path
Most Recently Used (MRU)
Round Robin (RR)

Let’s look at some examples of the three PSPs we’ve mentioned and how they behave. The definitions come from the vSphere 5 storage guide found below.

SAN Snapshots vs VMware Snapshots

Tue, 28 Feb 2012 02:33:24 +0000

I found people have a hard time understanding that a SAN Snapshot and a VMware snapshot are fundamentally different. I think because unless you’re a storage administrator, you’re probably not dealing a whole lot with snaps to begin with. VMware has made it more commonplace for System Administrators to deal with snapshot technology.

SAN Snapshots

Lets first look at how traditional SANs take snapshots.

To start we have 6 blocks being used. The file system has marked blocks which blocks are being used.