FC vs FATA vs TAPE

[apple]

Dear All,
what is the relative performance different between FC, FATA and TAPE (LTO4)? in term of xx/MB perseconds or may be range of speed? we would like to justify how FC can perform better in terms of speed of processing etc among of other thing. 15krpm/10krpm is not easy to explain to user.
Hope to hear from you. Thank you

[Trygve Henriksen]

I'm not really certain what you're asking about...

FC - Fibre Channel. This is a fibre-optic network technology used to connect servers to storage devices. Speeds are 'quite good' 4Gbit/s or even 8Gbit/s.

FATA - This is a normal ATA/SATA drive with a FC interface. It can communicate with the server at the speed of the FC network, but it can't process data(read from disk/write to disk) faster than an ATA/SATA disk can.

TAPE - As the name suggests, a Tape drive. how fast it can communicate with the server depends on the interface(SCSI/eSATA/FC/whatever), but the speed at which it transfers the data(read from/write to tape) is limited by the mechanics and media. See this page for some speeds:
http://h10010.www1.hp.com/wwpc/us/en/sm/WF25b/12169-304612-3446236-3446236-3446236-4150338.html
note that if the server can't keep a certain minimum data stream(about 1.5Mbit/s on LTO3, I think. Not certain about LTO4), the drive will be forced to stop and rewind periodically, and this will slow the transfer way down.

Note that FC is usually a Switched network, so that multiple units can talk at the same time.

[Víctor Cespón]

First you must differentiate between sequential and ramdom access.

Tape devices are sequential access devices, and pretty useless for random access.

FATA drives are slower than FC 10K and 15K drives.

It all depends what kind of transfers you're going to do.

An LTO drive can write 240MB/sec, as long as the server can provide it a continous stream of data.

If you're talking about storing a database, vitual machines, application data that has to be read and written continouslly, then you need to store that on disk drives.
The more disk drives the more random reads and writes you can do per second.

If you have one HDD and are doing random reads/writes of 4K, you're going to get 160*4K = 640 KB/s. If you're doing sequential reads of 256 KB, you can get 80 or 100 MB/s. It all depends on the kind of traffic.

[sam bell]

Hi Victor,

how did you calculate the 80/100MB/s when doing sequential reads with 256K blocks?

You wrote aboute 160IOPS with random reads (160x4KB). Is there also a literature value of IOPS for sequential performanc? Since as far as I know the literature IOPS value is all about random performance.

Thanks