usb memory stick and ext3

[Lonni J Friedman]

On Mon, May 4, 2009 at 6:46 PM, Vu Pham <vu at sivell.com> wrote:
> Lonni J Friedman wrote:
>>
>> On Mon, May 4, 2009 at 5:46 PM, Vu Pham <vu at sivell.com> wrote:
>>>
>>> I have a client who uses usb memory stick for backup of their database.
>>> The
>>> memory stick is formatted as ext3 and mounted then database is copied
>>> over
>>> at night. Everyday the same set of files ( same names  ) are copied over.
>>>
>>> I notice that for an empty stick, cp copies files at a reasonable speed
>>> but
>>> for a stick that already has data, cp runs extremely slowly. After a
>>> reformat ( mkfs.ext3 ) the cp runs fast again.
>>>
>>> Any reason for this ? Anyone uses memory stick for backup ? Any
>>> recommendation ?
>>
>> Your realize that SS media have a woefully inadequate lifespan, and
>> using them for backups is just about pointless.
>>
>> Also, what's the point in putting a journaled filesystem on a USB
>> stick?  IO perf is quite poor on most of them to begin with, and with
>> the journaling overhead, its got to be atrocious.
>>
>
> Thanks, Lonni. This client will eventually use some kind of external hard
> drives for their backup. For some reason, they do not have those drives now
> and want to set up the backup script so that it will also run when  they
> replace usb stick with their hard drives.
>
> I am curious why speed changes a lot when the usb stick already has files.

Most likely because its overwriting them, plus updating the journal.

-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
L. Friedman                                    netllama at gmail.com
LlamaLand                       https://netllama.linux-sxs.org