Re: [Xen-users] iscsi vs nfs for xen VMs

[Christian Zoffoli <czoffoli@xxxxxxxxxxx>]

Il 29/01/2011 16:08, Pasi Kärkkäinen ha scritto:
[cut]
> Microsoft and Intel had some press releases around one year ago
> demonstrating over one *million* IOPS using a single 10gbit Intel NIC,
> on a *single* x86 box, using *software* iSCSI.

there is a big differece between marketing numbers and real numbers.

The test you have pointed is only smoke in the eyes.

Noone published the hardware list they have used to reach such performances.

First of all they have aggregated the perfomances of *10* targets (if
the math is not changed 1 aggregator+10 targets == 11) and they have not
said what kind of hard disk and how many hard disks they used to reach
these performances.

The best std hard disk -> SAS 2.5 15k can do ~190 IOPS so it's quite
impossible to archive such IOPS, the only way is to use SSDs or better
PCIe SSDs ...but as everyone knows you have to pay 2 arms, 2 legs and so on.

In real life is very hard to reach high performance levels, for example:
- 48x 2.5IN 15k disks in raid0 gives you ~8700 RW IOPS (in raid 0 the %
of read doesn't impact on the results)

If you have enought money you can choose products from texas memory of
fusion-io but tipically the costs are too high.

For example a fusion ioDrive DUO 604GB  MLC costs ~15k $ ...if you want
1M IOPS you can choose the IODRIVE OCTAL ...but if we make the
proportion it should be over 120k $.


Christian

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