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Old 12-16-2009, 01:20 PM
Chan Chung Hang Christopher
 
Default LVM, usb drives, Active Directory

Steve Thompson wrote:
> On Tue, 15 Dec 2009, Scott Ehrlich wrote:
>
>> I have a client with a handful of USB drives connected to a CentOS
>> box. I am charged with binding the USB drives together into a single
>> LVM for a cheap storage data pool (10 x 1 TB usb drives = 10 TB cheap
>> storage in a single mount point).
>
> I tried doing this for fun once upon a time, using 6 1TB drives. I can
> save you a lot of grief by suggesting that you don't think about this any
> further. Boy is it slow. And extremely unreliable. And slow. Don't even do
> it for backups. Did I say it was slow?
>

Please qualify 'slow'. Was it dog slow, turtle-slow, snail-slow or
slowaris slow?

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Old 12-16-2009, 01:31 PM
Steve Thompson
 
Default LVM, usb drives, Active Directory

On Wed, 16 Dec 2009, Chan Chung Hang Christopher wrote:

> Steve Thompson wrote:
>> On Tue, 15 Dec 2009, Scott Ehrlich wrote:
>>
>>> I have a client with a handful of USB drives connected to a CentOS
>>> box. I am charged with binding the USB drives together into a single
>>> LVM for a cheap storage data pool (10 x 1 TB usb drives = 10 TB cheap
>>> storage in a single mount point).
>>
>> I tried doing this for fun once upon a time, using 6 1TB drives. I can
>> save you a lot of grief by suggesting that you don't think about this any
>> further. Boy is it slow. And extremely unreliable. And slow. Don't even do
>> it for backups. Did I say it was slow?
>
> Please qualify 'slow'. Was it dog slow, turtle-slow, snail-slow or
> slowaris slow?

Slower than all of those. Top write speed I could ever achieve with a
USB-2 interface and SATA drives was 20 MB/sec with a trailing wind, and
usually half of that, with a single stream. I even tried USB-1 for more
laughs; 1 MB/sec on a truly good day. With multiple writers, performance
dropped so far as to be unusable (below 1 MB/sec). And we're talking mkfs
times in _days_. The host was a CentOS 5.2 box, 32-bit.

Steve
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Old 12-16-2009, 01:31 PM
Chan Chung Hang Christopher
 
Default LVM, usb drives, Active Directory

Scott Ehrlich wrote:
> I have a client with a handful of USB drives connected to a CentOS
> box. I am charged with binding the USB drives together into a single
> LVM for a cheap storage data pool (10 x 1 TB usb drives = 10 TB cheap
> storage in a single mount point).

How about eSATA? Surely an eSATA enclosure for 10 drives won't be more
expensive than ten individual usb enclosures?!

>
> The next fun piece is how to incorporate that storage space into an
> existing Active Directory structure to apply AD acls for limited
> access.

AD does not have acls. NTFS does. The closet things to NTFS acls in UNIX
is nfs4 acls. That you can get with ZFS. I suggest that you give
OpenSolaris a shot instead. Or you can be one of the testers for
ntfs-3g's acl implementation...

>
> I'd rather not use Samba, as that is its own infrastructure and
> maintains its own credentials database.

Have you ever used winbind? It maps AD credentials to POSIX credentials.

>
> What are my best options?

Stuff not provided by Centos/RHEL at the moment.
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Old 12-16-2009, 01:34 PM
Chan Chung Hang Christopher
 
Default LVM, usb drives, Active Directory

Steve Thompson wrote:
> On Wed, 16 Dec 2009, Chan Chung Hang Christopher wrote:
>
>> Steve Thompson wrote:
>>> On Tue, 15 Dec 2009, Scott Ehrlich wrote:
>>>
>>>> I have a client with a handful of USB drives connected to a CentOS
>>>> box. I am charged with binding the USB drives together into a single
>>>> LVM for a cheap storage data pool (10 x 1 TB usb drives = 10 TB cheap
>>>> storage in a single mount point).
>>> I tried doing this for fun once upon a time, using 6 1TB drives. I can
>>> save you a lot of grief by suggesting that you don't think about this any
>>> further. Boy is it slow. And extremely unreliable. And slow. Don't even do
>>> it for backups. Did I say it was slow?
>> Please qualify 'slow'. Was it dog slow, turtle-slow, snail-slow or
>> slowaris slow?
>
> Slower than all of those. Top write speed I could ever achieve with a
> USB-2 interface and SATA drives was 20 MB/sec with a trailing wind, and
> usually half of that, with a single stream. I even tried USB-1 for more
> laughs; 1 MB/sec on a truly good day. With multiple writers, performance
> dropped so far as to be unusable (below 1 MB/sec). And we're talking mkfs
> times in _days_. The host was a CentOS 5.2 box, 32-bit.

Kudos to Steve for proving that USB2's 480mbits/sec is really just a sham.

Now I wonder if you can daisy chain IEEE1394 devices...or try out
eSATA...:-P
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Old 12-16-2009, 01:41 PM
William Warren
 
Default LVM, usb drives, Active Directory

On 12/16/2009 12:10 AM, Eero Volotinen wrote:
> On 12/15/09 2:48 PM, Scott Ehrlich wrote:
>
>> I have a client with a handful of USB drives connected to a CentOS
>> box. I am charged with binding the USB drives together into a single
>> LVM for a cheap storage data pool (10 x 1 TB usb drives = 10 TB cheap
>> storage in a single mount point).
>>
> Err.. buy computer from supermicro and load it with 10 sata disks.
>
> http://www.supermicro.com/products/chassis/2U/?chs=213
>
> --
> Eero
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> CentOS mailing list
> CentOS@centos.org
> http://lists.centos.org/mailman/listinfo/centos
>
>
>
Still going to need 10TB of backups. And i can guarantee you the
chances of having a URE during rebuild are almost certain with this
setup so a backup is going to be crucial. Sounds like a nightmare even
inside a supermicro or similar box.
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Old 12-16-2009, 01:50 PM
William Warren
 
Default LVM, usb drives, Active Directory

On 12/16/2009 9:34 AM, Chan Chung Hang Christopher wrote:
> Steve Thompson wrote:
>
>> On Wed, 16 Dec 2009, Chan Chung Hang Christopher wrote:
>>
>>
>>> Steve Thompson wrote:
>>>
>>>> On Tue, 15 Dec 2009, Scott Ehrlich wrote:
>>>>
>>>>
>>>>> I have a client with a handful of USB drives connected to a CentOS
>>>>> box. I am charged with binding the USB drives together into a single
>>>>> LVM for a cheap storage data pool (10 x 1 TB usb drives = 10 TB cheap
>>>>> storage in a single mount point).
>>>>>
>>>> I tried doing this for fun once upon a time, using 6 1TB drives. I can
>>>> save you a lot of grief by suggesting that you don't think about this any
>>>> further. Boy is it slow. And extremely unreliable. And slow. Don't even do
>>>> it for backups. Did I say it was slow?
>>>>
>>> Please qualify 'slow'. Was it dog slow, turtle-slow, snail-slow or
>>> slowaris slow?
>>>
>> Slower than all of those. Top write speed I could ever achieve with a
>> USB-2 interface and SATA drives was 20 MB/sec with a trailing wind, and
>> usually half of that, with a single stream. I even tried USB-1 for more
>> laughs; 1 MB/sec on a truly good day. With multiple writers, performance
>> dropped so far as to be unusable (below 1 MB/sec). And we're talking mkfs
>> times in _days_. The host was a CentOS 5.2 box, 32-bit.
>>
> Kudos to Steve for proving that USB2's 480mbits/sec is really just a sham.
>
> Now I wonder if you can daisy chain IEEE1394 devices...or try out
> eSATA...:-P
> _______________________________________________
> CentOS mailing list
> CentOS@centos.org
> http://lists.centos.org/mailman/listinfo/centos
>
>
>
Any host based technology won't get you half of the claimed speed with
any kind of reliability. I don't think ti will ever really outrun
something like SATAII or SAS. What makes it funnier is Intel is saying
this will make external RAID on USB possible...just keep in mind FRIAD
and that's what USB RAID really is.
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Old 12-16-2009, 01:52 PM
Thomas Harold
 
Default LVM, usb drives, Active Directory

On 12/15/2009 7:48 AM, Scott Ehrlich wrote:
> I have a client with a handful of USB drives connected to a CentOS
> box. I am charged with binding the USB drives together into a single
> LVM for a cheap storage data pool (10 x 1 TB usb drives = 10 TB cheap
> storage in a single mount point).
>
(snip)

> What are my best options?
>

Um, don't? Like other people said, go with eSATA, hopefully hooked up
to a 4-drive or 8-drive enclosure (or even a 10-drive enclosure).

Alternately, go with an external SAS storage rack that supports both SAS
/ SATA drives. A SAS card for PCIe is fairly inexpensive ($200?) and
the external enclosures are probably going to be (but not certainly)
better made then inexpensive SATA enclosures.

The big problem with USB is that it only supports about 25MB/s per port,
which means that it's going to be very very slow. Modern hard drives
can push 50-80MB/s easily.
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