Another issue to consider with SSDs is that they are based on Flash technology. Each flash cell can only be written on about 10,000 to 100,000 times or so (*), so if you're using extensive read/write on your server you will be impacted. SSD manufacturers go around this issue by giving some intelligence to the drive controllers, so that they minimize the per-cell usage (which means moving things around a bit internally, transparently to you), so in many cases you will not see any impact. However, I would be careful on what I run on it, and what services are enabled, maybe having another disk around for write intensive apps.
Emanuel
(*) http://en.wikipedia.org/wiki/Solid-state_drive#Disadvantages
---- Emanuel Machado, PhD. Senior Engineer, Project Leader
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-----Original Message----- From: centos-bounces@centos.org [mailto:centos-bounces@centos.org] On Behalf Of centos-request@centos.org Sent: Wednesday, January 13, 2010 12:00 PM To: centos@centos.org Subject: CentOS Digest, Vol 60, Issue 13
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Emanuel Machado wrote:
Another issue to consider with SSDs is that they are based on Flash technology. Each flash cell can only be written on about 10,000 to 100,000 times or so (*), so if you're using extensive read/write on your server you will be impacted. SSD manufacturers go around this issue by giving some intelligence to the drive controllers, so that they minimize the per-cell usage (which means moving things around a bit internally, transparently to you), so in many cases you will not see any impact. However, I would be careful on what I run on it, and what services are enabled, maybe having another disk around for write intensive apps.
No, you can write (append) as often as you like. It is the erase cycles that are limited. So the chip life depends on how often those files get deleted.
Bob McConnell N2SPP
On 1/13/2010 3:31 PM, Bob McConnell wrote:
Emanuel Machado wrote:
Another issue to consider with SSDs is that they are based on Flash technology. Each flash cell can only be written on about 10,000 to 100,000 times or so (*), so if you're using extensive read/write on your server you will be impacted. SSD manufacturers go around this issue by giving some intelligence to the drive controllers, so that they minimize the per-cell usage (which means moving things around a bit internally, transparently to you), so in many cases you will not see any impact. However, I would be careful on what I run on it, and what services are enabled, maybe having another disk around for write intensive apps.
No, you can write (append) as often as you like. It is the erase cycles that are limited. So the chip life depends on how often those files get deleted.
But every time you append to a file the inode info is updated and the free space list may need to be rewritten so it dies when erase/write count is exceeded on the filesystem metadata. If you don't turn off atime updates, you'll rewrite even on file reads.
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Bob McConnell -
Emanuel Machado -
Les Mikesell