Am 20.02.10 01:33, schrieb Toby Thain:
On 19-Feb-10, at 5:40 PM, Eugen Leitl wrote:
On Fri, Feb 19, 2010 at 11:17:29PM +0100, Felix Buenemann wrote:
I found the Hyperdrive 5/5M, which is a half-height drive bay sata
ramdisk with battery backup and auto-backup to compact flash at power
failure.
Promises 65,000 IOPS and thus should be great for ZIL. It's pretty
reasonable priced (~230 EUR) and stacked with 4GB or 8GB DDR2-ECC should
be more than sufficient.
Wouldn't it be better investing these 300-350 EUR into 16 GByte or
more of
system memory, and a cheap UPS?
That would depend on the read/write mix, I think?
Well the workload will include MaxDB (SAP), Exchange and file services
(SMB), with the opensolaris box acting as a VMFS iSCSI target for VMware
vSphere. Due to the mixed workload it's hard to predict how exactly the
I/O distribution will look like, so I'm trying to build a system that
can hold up in various usage scenarios.
I've been testing with NFS because it loads the ZIL heavily.
Btw. in my testing I didn't really see a performance improvement with
ZIL disabled over on disk ZIL, but I've only been testing with a single
NFS client. Or do I need multiple concurrent clients to benefit from
external ZIL?
Also is there a guideline on sizing the ZIL? I think in most cases even
1GB would be enough, but I haven't done any heavy testing.
--Toby
- Felix
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