Brad Fitzpatrick (brad) wrote,
Brad Fitzpatrick
brad

Size of journals

I've been doing a lot of work this morning calculating "how big" journals are, and how much disk space we'll need going forward. (especially as our months-long migration from MyISAM to InnoDB continues)

First I calculated MB/journal on 4 InnoDB clusters and got:

0.139
0.184
0.091
0.625 -- what?

The first 3 numbers (and especially the first 2) were promising, but then I realized I would have to factor in account age.

So I calculated bytes/day/journal: (day == total sum of account ages in days across all journals on a cluster)

1036.59
927.1858
955.3326
1071.819

Much more consistent!

BTW, these sizes are considering all data and indexes on a single machine, but not redundant copies of data in the cluster, or backups.

So once somebody signs up, historically, on average, their account grows by about 1 kB per day. With 5.3 million users, that's 5.04 GiB/day. Considering redundant copies and backups, that's more like 20 GiB/day.

See why I hate disks?

Update: the data above is bogus, because our moving process has been moving active users onto InnoDB first, and active accounts are bigger. I'll post better numbers later.
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