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in iSeries Storage?
14
Toronto Users Group for Midrange Systems November 2001
Whats Hot and New
in
iSeries
Storage?
By Nancy Roper
Introduction
ub the magic lamp a little harder, because the genie inside has
been granting lots of wishes for iSeries customers in the storage
arena in the past year, and will continue to do so in the months
and years to come. It all started with the announcement of
LTO tape technology in the fall of 2000, and has continued
with the addition of SAN and fibre channel technology in recent months.
These technologies, combined with the new iSeries processors, are letting
customers backup their systems at lightning speeds, with distance and
connectivity options that theyve been dreaming about for years. The
fibre technologies have also made iSeries attachment to external storage
subsystems a viable option for enterprise customers who are looking to
consolidate their storage.
So what is all this hype about storage, and
how do you use it to your advantage,
you ask? Well, read on! This article
will talk about the iSeries entrance
into the fibre channel world. It will
describe the new LTO and fibre-tape
options available, explain the main V5R1
BRMS enhancements, and introduce you
to external disk storage and the benefits
it can provide.
The iSeries enters the SAN world!
When V5R1 was announced, the iSeries
formally entered the Storage Area
Network (SAN) world. New fibre adapter
cards for the 270 and 8xx processors
were announced that will attach fibre
channel tape (adapter card feature code
#2765) and external disk (adapter card
feature code #2766).
So what is a Storage Area Network, you
ask? Well, lets look at what weve had
in the past, then compare it to a SAN:
In the past, disk and tape were direct-
attached to the AS/400 and iSeries via
SCSI cables that could be at most 25m
long. Each server owned its own
storage. For example, disk drives were
right inside the servers and not shared
between systems.
Tape drives were dedicated to one
system, or sometimes shared between
two systems. Transmissions ran at SCSI
speeds.
By comparison, in a SAN environment,
the SCSI cables are replaced by a high
speed, interconnected storage network,
typically running across fibre channel
cables, with hubs and switches and other
SAN devices mixed in for connectivity
and redundancy. This network can
provide any to any connectivity among
the servers and the storage devices.
Distances of 10 km can be achieved
easily. Performance today is up to
100 MB/sec, with 200 MB/sec devices
beginning to come to market, and 400
MB/sec devices on the horizon. A SAN
can be as simple as a single orange
fibre cable running between an iSeries
and a fibre tape drive, or it can be as
complex as a multi-platform, enterprise
wide network, complete with monitoring
tools, etc.
So what does this mean to you?
Improved Connectivity: Have you ever
been frustrated that you had to buy an
extra tape drive, not because your existing
drive was overloaded, but because it only
had 2 ports and you had 3 systems? Or
have you ever wanted to run a save,
and found you had lots of idle drives in
your tape library, but none of them was
attached to the system that needed the
backup? With fibre channel, these issues
go away. You can use switches and
hubs to attach multiple hosts to multiple
drives to give great flexibility in your
operations.
Improved Distance: Did you ever
consider doing remote backups, whereby
your CPU was in one building, and your
tape drive was in another, thus saving the
need to send your tapes offsite? Or did
you ever want to lock your CPUs in your
computer room, but put the drives out
closer to your operators?
Nancy Roper
Figure 1
Figure 2.
XChange Xcellence Award Toronto Users Group for Midrange Systems November 2001
15
With fibre channel, options like these become available, because
you can separate your host and your storage by 10 km with
ease.
Improved Performance: Have you been wondering how you
can squeeze your backup into the tiny save window left after
the demands of global operations and e-business? Well, SAN
and fibre channel answer this challenge too. The high speed of
fibre channel, combined with the new HSL bus connections on
270 and 8xx iSeries CPUs, will make your backups fly. This
high speed connection will also make external disk viable in an
iSeries environment.
In order to start using fibre channel and SAN on your iSeries,
you will need to be on the latest hardware models (270 or
8xx), and the latest version of the operating system (V5R1),
along with the new fibre attachment cards. Initially, the
iSeries will use a fibre-channel arbitrated loop topology for
storage area networks, with fabric-mode being added in future
releases. Initially, the SAN devices that will be supported on
iSeries to connect multiple hosts to the storage are the 3534
IBM TotalStorage SAN Managed Hub and the 2109 IBM
TotalStorage SAN Switch.
For further information on iSeries SAN, please refer to
the redbook entitled iSeries in Storage Area Networks
(SG24-6220)
at
www.redbooks.ibm.com
.
LTO Tape
A new tape technology has taken the market by storm in recent
months. It is called Linear Tape Open (LTO) and is very well
suited to the iSeries marketplace. Three tape vendors, IBM, HP,
and Seagate worked together to describe the specification for
LTO. Their goal was to create a product to replace the aging
and proprietary 8mm and DLT products that are in common use
on iSeries, xSeries, and Unix servers. In their specification, the
team demanded that the initial LTO drives be high speed (at
least 10-20 MB/s before compression), high capacity (at least
100 GB per tape before compression), reliable, economical, and
open. They then drafted a four generation technology roadmap
that shows the LTO drives doubling in speed and capacity
every 18-24 months. The result of the teams work was a drive
that competes with the high-end drives on performance and
function, but is priced in the same neighbourhood as the low-
end drives. It excels at the streaming tape operations that are
typical on the iSeries platform.
IBM was first to market with an LTO product set, and very
quickly won the "XChange Xcellence Award" award for Best
New Product Hardware Division (Figures 1 & 2) at CMP's
Solution Provider Xchange show in New Orleans in April 2001.
IBMs product line includes the following devices:
The 3580 (Figure 3) is a single drive, single cartridge
device that is so small and light you can carry it in
one hand. It attaches to a single host. In a typical
iSeries environment (3:1 compression), this drive
can save 300 GB of data unattended. For many systems, this
means that the entire system save would fit on a single tape.
This drive is available in SCSI models only.
The 3581 (Figure 4) is a single drive device
that can hold up to 7 cartridges for a total of
2.1 TB of unattended storage in a typical iSeries
environment (3:1 compression). It attaches to a
single host. This drive can be used in sequential
mode where the tapes are used one by one in order. Alternatively,
it can be switched into random-mode to behave like a mini tape
library, whereby the tapes can be accessed in any order, and
tapes can be remounted without operator intervention. There is
an optional barcode reader that is beneficial when running in
random mode: it uses one of the cartridge slots. This drive is
available in SCSI models only.
The 3583 (Figure 5) is a small tape library
that can hold from 18 to 72 cartridges. In
an iSeries environment, the SCSI model can
attach to a single host and can have one drive.
The fibre model has 2 fibre ports and can
have from 1-6 drives. Two iSeries hosts can
be attached directly via the
fibre ports, or multiple iSeries hosts can be
attached via hubs and switches. In each case,
all hosts can access all drives.
The 3584 (Figure 6) is an enterprise-sized
tape library that can hold from 141 to 2481
cartridges. It is similar in appearance to a
3494. Each frame can hold up to 12 drives,
Figure 3
Figure 4
Figure 5
Figure 6
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Toronto Users Group for Midrange Systems November 2001
and a library can have from 1-6 frames.
A mixture of SCSI and fibre drives can
be placed in a single 3584. SCSI drives
can each attach to a single host. Fibre
drives can each direct-attach to a single
host, or they can attach to multiple hosts
via hubs or switches. DLT drives can
also be put in a 3584 for use with other
host platforms, but DLT is not supported
on the AS/400 or iSeries.
A key feature of the 3584 is the ability
to partition it into multiple independent
libraries. This can be done using barcode
stickers on the inside of the library to
carve off tape drives and entire columns
of media. Alternatively it can be done
via the front