From: Greg Smith <greg@2ndQuadrant.com>
To: Tomas Vondra <tv@fuzzy.cz>
Cc: pgsql-performance@postgresql.org
Subject: Re: Reliability with RAID 10 SSD and Streaming Replication
Date: Sun, 19 May 2013 23:00:59 -0400
Message-ID: <519991EB.8010208@2ndQuadrant.com> (raw)
In-Reply-To: <51957499.6050905@fuzzy.cz>
References: <CAAE-9WHMycEZOB5J6HKME5AZLEdL2hYF+FV8hzbLksJinq=EJg@mail.gmail.com>
<51957499.6050905@fuzzy.cz>
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On 5/16/13 8:06 PM, Tomas Vondra wrote:
> Have you considered using a UPS? That would make the SSDs about as
> reliable as SATA/SAS drives - the UPS may fail, but so may a BBU unit on
> the SAS controller.
That's not true at all. Any decent RAID controller will have an option
to stop write-back caching when the battery is bad. Things will slow
badly when that happens, but there is zero data risk from a short-term
BBU failure. The only serious risk with a good BBU setup are that
you'll have a power failure lasting so long that the battery runs down
before the cache can be flushed to disk.
--
Greg Smith 2ndQuadrant US greg@2ndQuadrant.com Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.com
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To: pgsql-performance@postgresql.org
Cc: greg@2ndQuadrant.com, tv@fuzzy.cz
Subject: Re: Reliability with RAID 10 SSD and Streaming Replication
In-Reply-To: <519991EB.8010208@2ndQuadrant.com>
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