HP StoreOpen LTFS

[Kiki Muchtar]

“If you can’t read 180MB/sec off of the disk, you’ll never be able to stream 1 LTO-6, let alone 2.”

Our HDD (as source) speed is more than 150 MB/s but never reach 180 MB/s. We archive from that HDD (1 tape at a time), and we’ve tried to retrieve the data back from the LTO tape, and it worked fine. We use HP StoreOpenLTFS & Terminal app. Is there any possibility that something actually isn’t right?

[Tim Jones]

Hi Kiki,

The issue is simply one of performance. That comment was made in reference to running 2 tapes simultaneously on 2 drives.

The point is that if you can’t read the data from the source disk faster than the tape drive can write, the tape drive will suffer from underruns which causes shoe-shining and slows the writes even further. The slower your disk, the slower your backup / restore operations.

Tim
—
Tim Jones
CTO – TOLIS Group, Inc.
https://www.tolisgroup.com
BRU … because it’s the RESTORE that matters!

[Kiki Muchtar]

Hi Tim,

Understood, so disk array with USB 3.0 or, I assume, Thunderbolt are good enough. What about speedy server (RAID, 7200 rpm) with 1 GigE connection, will it gain the speed we’re looking for?

Cheers,
Kiki

[Tim Jones]

Nope – your limitation there is 1GbE. That results in maximum of 88MB/sec cooked data (data after network packet infrastructure is stripped off).

It’s always the slowest component that affects your throughput:

Slow 5400RPM drive = 60MB/sec
Single 7200RPM drive = 88MB/sec
Singe 10KRPM drive = 120MB/sec
2, 3, 4, etc. – multiplied throughput up to the speed of your interconnect (net, SAS, FC, Thunderbolt, USB-3)

USB-3 = 430MB/sec MAX
eSATA = 520MB/sec MAX
Thunderbolt 1 = 800MB/sec MAX
Thunderbolt 2 = 1.54GB/sec MAX
SAS 6Gb = 580MB/sec per channel MAX
SAS 12GB = 1.1GB/sec per channel MAX
FC 8Gb = 775MB/sec MAX
FC 16Gb = 1.52MB/sec MAX

1GbE Network = 88MB/sec
10GbE Network = 920MB/sec

A 1 drive, 7200RPM drive will do 88MB/sec on any of those connections
An 8 drive, 7200RPM RAID 0 chassis that COULD do 700MB/sec connected via Thunderbolt 2 would top out at 700MB/sec, Thunderbolt 1 would top out at 700MB/sec, and via USB-3 would top out at 430MB/sec.
A 4 drive, 7200PM RAID 0 chassis that could do 352 MB/sec would run at 352MB/sec regardless of the interconnect layer.

* all numbers are ±5% and come from real world lab tests.

Tim
—
Tim Jones
CTO – TOLIS Group, Inc.
https://www.tolisgroup.com
BRU … because it’s the RESTORE that matters!

[David Roth weiss]

[Tim Jones] “The point is that if you can’t read the data from the source disk faster than the tape drive can write, the tape drive will suffer from underruns which causes shoe-shining and slows the writes even further.”

Love the term “shoe-shining” Tim, can you define that term for me so I can use it properly?

TIA,
David

David Roth Weiss
Director/Editor/Colorist & Workflow Consultant
David Weiss Productions
Los Angeles

David is a Creative COW contributing editor and a forum host of the Apple Final Cut Pro forum.

[David Roth weiss]

[Tim Jones] “It’s always the slowest component that affects your throughput:

Slow 5400RPM drive = 60MB/sec
Single 7200RPM drive = 88MB/sec
Singe 10KRPM drive = 120MB/sec
2, 3, 4, etc. – multiplied throughput up to the speed of your interconnect (net, SAS, FC, Thunderbolt, USB-3)

USB-3 = 430MB/sec MAX
eSATA = 520MB/sec MAX
Thunderbolt 1 = 800MB/sec MAX
Thunderbolt 2 = 1.54GB/sec MAX
SAS 6Gb = 580MB/sec per channel MAX
SAS 12GB = 1.1GB/sec per channel MAX
FC 8Gb = 775MB/sec MAX
FC 16Gb = 1.52MB/sec MAX

1GbE Network = 88MB/sec
10GbE Network = 920MB/sec

A 1 drive, 7200RPM drive will do 88MB/sec on any of those connections
An 8 drive, 7200RPM RAID 0 chassis that COULD do 700MB/sec connected via Thunderbolt 2 would top out at 700MB/sec, Thunderbolt 1 would top out at 700MB/sec, and via USB-3 would top out at 430MB/sec.
A 4 drive, 7200PM RAID 0 chassis that could do 352 MB/sec would run at 352MB/sec regardless of the interconnect layer.

* all numbers are ±5% and come from real world lab tests.”

What a beautifully compact and efficient “factoid.” Maybe Tim Wilson should encourage you to think about putting this in an FAQ at the top of this forum (and possibly others too)???

David Roth Weiss
Director/Editor/Colorist & Workflow Consultant
David Weiss Productions
Los Angeles

David is a Creative COW contributing editor and a forum host of the Apple Final Cut Pro forum.