> On Nov 11, 2020, at 6:00 PM, John Pierce <jhn.pierce@xxxxxxxxx> wrote:
>
> On Wed, Nov 11, 2020 at 3:38 PM Warren Young <warren@xxxxxxxxxxx> wrote:
>
>> On Nov 11, 2020, at 2:01 PM, hw <hw@xxxxxxxx> wrote:
>>>
>>> I have yet to see software RAID that doesn't kill the performance.
>>
>> When was the last time you tried it?
>>
>> Why would you expect that a modern 8-core Intel CPU would impede I/O in
>> any measureable way as compared to the outdated single-core 32-bit RISC CPU
>> typically found on hardware RAID cards? These are the same CPUs, mind,
>> that regularly crunch through TLS 1.3 on line-rate fiber Ethernet links, a
>> much tougher task than mediating spinning disk I/O.
>
>
> the only 'advantage' hardware raid has is write-back caching.
Just for my information: how do you map failed software RAID drive to physical port of, say, SAS-attached enclosure. I’d love to hot replace failed drives in software RAIDs, have over hundred physical drives attached to a machine. Do not criticize, this is box installed by someone else, I have “inherited” it.To replace I have to query drive serial number, power off the machine and pulling drives one at a time read the labels...
With hardware RAID that is not an issue, I always know which physical port failed drive is in. And I can tell controller to “indicate” specific drive (it blinks respective port LED). Always hot replacing drives in hardware RAIDs, no one ever knows it has been done. And I’d love to deal same way with drives in software RAIDs.
Thanks for advises in advance. And my apologies for “stealing the thread"
Valeri
> with ZFS you can get much the same performance boost out of a small fast
> SSD used as a ZIL / SLOG.
>
> --
> -john r pierce
> recycling used bits in santa cruz
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