SyncMirror mirror aggregates and work on a RAID level. You can configure mirroring between two shelves of the same system and prevent an outage in case of a shelf failure.
SyncMirror uses a concept of plexes to describe mirrored copies of data. You have two plexes: plex0 and plex1. Each plex consists of disks from a separate pool: pool0 or pool1. Disks are assigned to pools depending on cabling. Disks in each of the pools must be in separate shelves to ensure high availability. Once shelves are cabled, you enable SyncMiror and create a mirrored aggregate using the following syntax:
aggr create aggr_name -m -d disk-list -d disk-list
WAFL is our Write Anywhere File Layout. If NVRAM’s role is the most-commonly misunderstood, WAFL comes in 2nd. Yet WAFL has a simple goal, which is to write data in full stripes across the storage media. WAFL acts as an intermediary of sorts — there is a top half where files and volumes sit, and a bottom half (reference) that interacts with RAID, manages SnapShots and some other things. WAFL isn’t a filesystem, but it does some things a filesystem does; it can also contain filesystems. WAFL contains mechanisms for dealing with files & directories, for interacting with volumes & aggregates, and for interacting with RAID. If Data ONTAP is the heart of a NetApp controller, WAFL is the blood that it pumps.
Although WAFL can write anywhere we want, in reality we write where it makes the most sense: in the closest place (relative to the disk head) where we can write a complete stripe in order to minimize seek time on subsequent I/O requests. WAFL is optimized for writes, and we’ll see why below. Rather unusually for storage arrays, we can write client data and metadata anywhere.
Vservers : contain one or more FlexVol volumes, or a single Infinite Volume Volume : is like a partition that can span multiple physical disks LUN : is a big file that is inside the volume. the LUN is what gets presented to the host.
RAID, Volumes, LUNs and Aggregates
- An aggregate is the physical storage. It is made up of one or more raid groups of disks.
- A LUN is a logical representation of storage. It looks like a hard disk to the client. It looks like a file inside of a volume.
Raid groups are protected sets of disks. consising of 1 or 2 parity, and 1 or more data disks. We don’t build raid groups, they are built automatically behind the scene when you build an aggregate. For example: In a default configuration you are configured for RAID-DP and a 16 disk raid group (assuming FC/SAS disks). So, if i create a 16 disk aggregate i get 1 raid group. If I create a 32 disk aggregate, i get 2 raid groups. Raid groups can be adjusted in size. For FC/SAS they can be anywhere from 3 to 28 disks, with 16 being the default. You may be tempted to change the size so i have a quick/dirty summary of reasons. Continue reading
The NetApp filer also know as NetApp Fabric-Attached Storage (FAS) is a type of disk storage device which owns and controls a filesystem and present files and directories over the network, it uses an operating systems called Data ONTAP (based on FreeBSD).
NetApp Filers can offer the following:
- Supports SAN, NAS, FC, SATA, iSCSI, FCoE and Ethernet all on the same platform
- Supports either SATA, FC and SAS disk drives
- Supports block protocols such as iSCSI, Fibre Channel and AoE
- Supports file protocols such as NFS, CIFS , FTP, TFTP and HTTP
- High availability
- Easy Management
I have recently started working on a FlexPod environment. The environment relies on NetApp for all of its storage needs, but unfortunately I hadn’t worked with NetApp products before. Because of this I have been spending most of my spare time reading and labbing so that I could build my skills up as quickly as possible.
An issue I ran into, and what I plan to resolve with a series of posts, is the lack of structured information that is aimed at people who have not worked with NetApp products before. (I’m happy to be proven wrong so please feel free to comment on this post or e-mail me if you feel I am incorrect).