Re: [vserver] SSD/HD hybrids

From: Adrian Reyer <are_at_lihas.de>
Date: Thu 01 Apr 2010 - 13:45:47 BST
Message-ID: <20100401124547.GA18303@lihas.de>

On Thu, Apr 01, 2010 at 11:32:16AM +0200, Eugen Leitl wrote:
> Any additional ideas?

I'd save the money for the SSD and spend it on more RAM.
RAM = Cache. No SSD will be as fast as your RAM. Additionally, the base
install of a typical VServer has only a few 100 MB, by unifying them it
leads to having the base infrastructure of all VServers in RAM within a
short time.
The SSD part becomes intresting only if you have much more data than RAM
that you need to access in a random order rendering the cache useless.
Typical szenarios would be databases or huge IMAP servers.
I don't know what you actually run on the VServers, if it is network
servers like samba, apache, mail I'd not waste time on SSDs unless you
have way more than 1GBit/s NICs.
Personally I uses SATA disks almost everywhere with the possible
exception of databae servers, there SAS is an option.
iSCSI is no real benefit, it brings in extra letency, exactly what you
try and avoid with the SSDs. I built a 10GBit/s iSCSI infrastructure
recently and due to latencies I had to be comfortable with 60-350MB/s
depending on file sizes. Not exactly what was expected as a simple
1GBit/s iSCSI does 60-108MB/s in a similar setup.
Generally I'd use all kinds of SAN-setup only if I have many seperate
hardware boxes that require minimal disk space to get rid of the local
disks. With VServers you can just build real disks with fast controllers
right into the box.

Regards,
        Adrian

-- 
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Received on Thu Apr 1 13:46:14 2010
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