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Internal storage vs external storage

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February 27, 2014 12:36:35 AM

Hi,

Just wondering what are the pros and cons of getting a server with local storage vs getting an external storage (NAS or SAN)?

Thanks.
a c 88 G Storage
February 27, 2014 12:50:36 AM

sleepyhead87 said:
Hi,

Just wondering what are the pros and cons of getting a server with local storage vs getting an external storage (NAS or SAN)?

Thanks.


SANs are bloody expensive. Unless you run a large company with lots of on-site data storage, you won't ever need one.

As for the rest, it really depends on the use-case for the hardware.

In many cases (such as SATA vs eSATA, or SCSI variants), the only difference between internal storage and external storage is the physical location of the hardware and where it draws power from.

External storage that is attached over USB however can have some drawbacks as these are nothing more than commercial hard disk drives attached via a USB to ATA bridge. Performance is usually slower, quality of service is not guaranteed, and many ATA functions can't be safely used and will be ignored by the bridge driver.
February 27, 2014 1:24:27 AM

Pinhedd said:
sleepyhead87 said:
Hi,

Just wondering what are the pros and cons of getting a server with local storage vs getting an external storage (NAS or SAN)?

Thanks.


SANs are bloody expensive. Unless you run a large company with lots of on-site data storage, you won't ever need one.

As for the rest, it really depends on the use-case for the hardware.

In many cases (such as SATA vs eSATA, or SCSI variants), the only difference between internal storage and external storage is the physical location of the hardware and where it draws power from.

External storage that is attached over USB however can have some drawbacks as these are nothing more than commercial hard disk drives attached via a USB to ATA bridge. Performance is usually slower, quality of service is not guaranteed, and many ATA functions can't be safely used and will be ignored by the bridge driver.


Thanks for the reply.

What if the external storage is using FC or ISCSI, Is there any performance drawback between using local storage to write to application like database vs writing to the external storage? Also, is external storage such as SAN better in disk utilization? What about redundancy? I guess internal and external can both run RAID so there's not much difference right.

Thanks
a c 88 G Storage
February 27, 2014 1:35:37 AM

sleepyhead87 said:
Pinhedd said:
sleepyhead87 said:
Hi,

Just wondering what are the pros and cons of getting a server with local storage vs getting an external storage (NAS or SAN)?

Thanks.


SANs are bloody expensive. Unless you run a large company with lots of on-site data storage, you won't ever need one.

As for the rest, it really depends on the use-case for the hardware.

In many cases (such as SATA vs eSATA, or SCSI variants), the only difference between internal storage and external storage is the physical location of the hardware and where it draws power from.

External storage that is attached over USB however can have some drawbacks as these are nothing more than commercial hard disk drives attached via a USB to ATA bridge. Performance is usually slower, quality of service is not guaranteed, and many ATA functions can't be safely used and will be ignored by the bridge driver.


Thanks for the reply.

What if the external storage is using FC or ISCSI, Is there any performance drawback between using local storage to write to application like database vs writing to the external storage? Also, is external storage such as SAN better in disk utilization? What about redundancy? I guess internal and external can both run RAID so there's not much difference right.

Thanks


To be clear, SANs are absolute massive and cost truckloads of money. SANs can run anywhere from a half-rack (24u) to multiple full racks. The most common interface to SANs is a FC fabric (which is also obnoxiously expensive), but other interfaces such as iSCSI work as well.

Disk utilization on SANs is amazing, and they're often backed by huge amounts of SDRAM disk cache, often upwards of 64GiB of DDR3 per storage controller (of which there are two or more per SAN for redundancy and performance). However, this is for enormous enterprise deployments. For anything smaller, SAN is simply overkill.

If you're looking for a compact external storage solution there are some more appropriately sized SCSI RAID enclosures, or dedicated storage servers that have a large number of disk ports connected via a common backplane to a storage controller which is controlled by a low power CPU such as an Intel Atom or ARM CPU. These are functionally similar to a small SAN, but without the massive power draw of the storage controller and cost overhead of... the entire thing.

This seems like a question that you should be fielding to industry consultants or your own tech staff, not some random folks on the internet. Consider giving EMC, Dell, IBM, or HP a call. They'll be happy to send you a brochure I'm sure.
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