Re: [BackupPC-users] usb slow for random access? (was Re: Using rsync for blockdevice-level synchronisation of BackupPC pools)
2009-09-11 14:21:09
Dan Pritts wrote:
> On Wed, Sep 09, 2009 at 11:46:41AM +0200, Tino Schwarze wrote:
>> I'd say: Replace that USB 2.0 disk by something else like something
>> connected via Firewire or eSATA. USB 2.0 is very, very slow, especially
>> for random access.
>
> Hi Tino,
>
> do you have empirical results that show this?
>
> Not having tested it myself, that is exactly the opposite of what i
> would expect.
>
> random access times are dominated primarily by disk head seek time,
> which is gonna be the same no matter what the transport to the drive is.
> So the slower transport won't matter nearly as much with random I/O as
> it will with sequential.
>
> SATA or SAS/SCSI with command queueing should have better random access
> performance than anything without command queueing. However, I don't
> believe firewire has command queueing support, which would suggest that
> this isn't what you're thinking of.
I think USB has a bit more CPU overhead than firewire so firewire would
give somewhat better throughput. But eSATA or a hot-swap internal bay
for a bare SATA drive would be even better.
--
Les Mikesell
lesmikesell AT gmail DOT com
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- Re: [BackupPC-users] Using rsync for blockdevice-level synchronisation of BackupPC pools, (continued)
- Re: [BackupPC-users] Using rsync for blockdevice-level synchronisation of BackupPC pools, dan
- Re: [BackupPC-users] Using rsync for blockdevice-level synchronisation of BackupPC pools, Tino Schwarze
- Re: [BackupPC-users] Using rsync for blockdevice-level synchronisation of BackupPC pools, dan
- Re: [BackupPC-users] Using rsync for blockdevice-level synchronisation of BackupPC pools, Les Mikesell
- Re: [BackupPC-users] Using rsync for blockdevice-level synchronisation of BackupPC pools, dan
- Re: [BackupPC-users] Using rsync for blockdevice-level synchronisation of BackupPC pools, Tino Schwarze
- Re: [BackupPC-users] Using rsync for blockdevice-level synchronisation of BackupPC pools, Christian Völker
- Re: [BackupPC-users] Using rsync for blockdevice-level synchronisation of BackupPC pools, Tino Schwarze
- Re: [BackupPC-users] Using rsync for blockdevice-level synchronisation of BackupPC pools, Christian Völker
- [BackupPC-users] usb slow for random access? (was Re: Using rsync for blockdevice-level synchronisation of BackupPC pools), Dan Pritts
- Re: [BackupPC-users] usb slow for random access? (was Re: Using rsync for blockdevice-level synchronisation of BackupPC pools),
Les Mikesell <=
- Re: [BackupPC-users] usb slow for random access? (was Re: Using rsync for blockdevice-level synchronisation of BackupPC pools), Michael Stowe
- Re: [BackupPC-users] usb slow for random access? (was Re: Using rsync for blockdevice-level synchronisation of BackupPC pools), Dan Pritts
- Re: [BackupPC-users] usb slow for random access? (was Re: Using rsync for blockdevice-level synchronisation of BackupPC pools), Tino Schwarze
- Re: [BackupPC-users] usb slow for random access? (was Re: Using rsync for blockdevice-level synchronisation of BackupPC pools), dan
- Re: [BackupPC-users] usb slow for random access? (was Re: Using rsync for blockdevice-level synchronisation of BackupPC pools), Jim Leonard
- Re: [BackupPC-users] usb slow for random access? (was Re: Using rsync for blockdevice-level synchronisation of BackupPC pools), Dan Pritts
- Re: [BackupPC-users] Using rsync for blockdevice-level synchronisation of BackupPC pools, Pieter Wuille
- Re: [BackupPC-users] Using rsync for blockdevice-level synchronisation of BackupPC pools, Les Mikesell
- Re: [BackupPC-users] Using rsync for blockdevice-level synchronisation of BackupPC pools, Christian Völker
- Re: [BackupPC-users] Using rsync for blockdevice-level synchronisation of BackupPC pools, Christian Völker
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