Re: SSD usage

From: Andrew Kerber <andrew.kerber_at_gmail.com>
Date: Wed, 16 Dec 2015 10:12:14 -0600
Message-ID: <CAJvnOJZHFx4kHmremtGy1UPdD8vjQSZ5b=bMf3_FOrK6kRLeGA_at_mail.gmail.com>

Much of that depends on the quality of the SSD. Top end SSD improves write speed more than it improves read speed.

On Wed, Dec 16, 2015 at 9:21 AM, Kellyn Pot'Vin-Gorman <dbakevlar_at_gmail.com> wrote:

> I did extensive research to decide what should utilize SSD and found that
> it didn't hurt to put redo on SSD, but it didn't offer much benefit and
> you simply weren't investigating the real cause of the waits.
>
> I would choose to allocate the SSD to often used indexes or tables than to
> waste it on redo. Take the time to research the issue, as writes on SSD
> aren't as beneficial as reads and as we all know, redo is write intensive
> and the common wait issue.
>
> Kellyn Pot'Vin-Gorman
> Consulting Member of Technical Staff, Oracle
> On Dec 16, 2015 7:59 AM, "Andrew Kerber" <andrew.kerber_at_gmail.com> wrote:
>
>> Everything I have read has definitely recommended putting the redo logs
>> on SSD. I even wrote an article on the subject several years ago.
>>
>> On Wed, Dec 16, 2015 at 8:54 AM, Storey, Robert (DCSO) <
>> RStorey_at_dcso.nashville.org> wrote:
>>
>>> Morning,
>>>
>>>
>>>
>>> I’ve been reading multiple docs on SSD/HDD and the benefits within an
>>> oracle database.
>>>
>>>
>>>
>>> If I am reading this write, for an OLTP system, the SSD/FLASH will
>>> provide excellent random read/write abilities.
>>>
>>>
>>>
>>> But folks seem contradicted on using the SSD for the Redo logs. Some
>>> say its best practice, others say it does not buy you anything.
>>>
>>>
>>>
>>> I have a 24/7 OLTP application that generates a modest amount of redo.
>>> My overall DB is about 95 gigs, I generate about 600megs of redo in a day
>>> (10meg files, switching every 30 or so). My system is getting to end of
>>> life, and I see more log_file_sync waits, and buffer busy waits. I suspect
>>> my I/O subsystems are getting worked hard. My top waits appear to be
>>> sequent file reads and scattered reads, log file sync, and buffer busy.
>>>
>>>
>>>
>>> What’s the general verdict on using SSD for the data files? Best idea
>>> for redos? My thoughts there are separating them to different drives, ie,
>>> two separate single disks, with a group member on each disk.
>>>
>>>
>>>
>>>
>>>
>>> Thoughts?
>>>
>>>
>>>
>>> Thanks
>>>
>>
>>
>>
>> --
>> Andrew W. Kerber
>>
>> 'If at first you dont succeed, dont take up skydiving.'
>>
>

-- 
Andrew W. Kerber

'If at first you dont succeed, dont take up skydiving.'

--
http://www.freelists.org/webpage/oracle-l

Received on Wed Dec 16 2015 - 17:12:14 CET